CA1297421C - Mass production auditory canal hearing aid - Google Patents

Abstract

ABSTRACT

A new global, systematic approach has been taken to provide a better hearing aid and hearing aid delivery system. The in-the-canal hearing aid which is discussed and shown has patient selected physical components and patient selected electronic components. The construction of the hearing aid and the delivery system are such that a patient may personally select the best suited hearing aid during the testing process and walk away with the hearing aid he or she has personally selected. This is accomplished by allowing the patient to select a form fitting shell with a malleable covering having a hook and twist which precisely conforms to the patient's own ear.
The patient then listens to sounds with or without back-ground noise and from various directions using electronic components which conform to the specifications of the hearing aid and personally chooses those electronics which best aid or assist the patient's hearing loss. These electronics are then quickly inserted into the same shell that the patient has chosen for testing purposes and the patient may leave with the hearing aid that he or she has personally selected during the testing process. Repair or replacement is as easily accomplished by replacing the personalized shell if physical discomfort occurs or by replacing the electronics if a sound environment exists which was not anticipated during testing. The result is a truly personalized and personally chosen prothesis which is capable of on the spot delivery.

Description

129~429 BACKGROUND OF THE INVENTION

Related Application This application is related to Canadian Patent Application Serial No. 537,802, ~filed May 22, 1987 5 entitled PATIENT CONTROLLED MAsTER HEARING AID which disclosed a test apparatus for patient selection of the electronics to be incorporated into the hearing aid of this invention.

Field of the Invention This invention relates to the field of hearing aids, and more particularly to an in-the-canal miniaturized hearing aid which has all of its electrical and mechanical components, including a replaceable battery, contained within a prefabricated earshell assembly composed of a hollow rigid body with a soft, resilient covering fixed to the exterior.
Description of the Prlor Art Numerous types and designs of hearing aids for assisting persons with hearing deficiencies are known in the prior art. Typically, hearing aids incorporate a micro-phone for converting sound waves to electrical signals.
These signals are then amplified by an amplifier circuit and sent to a receiver. The receiver converts the electri-cal signals into amplified sound waves and directs the sound waves toward the eardrum~
Many efforts have been made to address the tragic impairment of;the~hearing~sense. It is believed that most of these prior contributions have assisted the patient who wore them and therefore they are important contribu-tions. It is believed that most, however, have, whileassisting in part the hearing problem, contributed other , ~

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The majority of prior devices include a bulky protrusion ~rom the ear, noticeable by all~ indicating that -the patient or user wears a hearing aidO A more recent S .~odification relocated the controls which protruded from the ear to a position in back of the ear Attempts to overcome the outward extending controls included the crea-tion of custom molded in-~he-canal hearing aidsO ~ ~
Most popular hearing aids today are very expensive and are created by this custom molding method or process : by which a soft silicone or similar ear impression material is used to take an impression of the patient's ear canal which is then used to creal~e a hard plastic shell or a hearing aid which conforms to the patient's ear~ However, after the har~ plastic She!ll i9 rendered from the ear itnpression, :individual tec!hnicians at the manu~acturiny plant cut, bu:eE and polis~ the hearing aid, often changing the con~iyuration or mold so that it no longer is able to conform precisely to the ear from which the first~
20 impression was taken. In addition, the baffing and l~
polishing which is done tc~ make ~he aid slip into the ear becomes the surface which permits feedback of sound to occur causing an unpleasant squeal in many circumstancesO
For example, bu~fing "roucJh spots":generated during the` ~:
ear irnpression process creates imperfections of the inter-ace between the hearing aid and the inner surface of the ear~ These imperfections cause Ipin prick" openings which permit sound from the receiver to leak back to the micro-;: phone. ~ ~
` 30 ~ Thus~ with~prior custom molded hea~ing aids there is oEten a need:for modifications to the device and repeated exchange between the patient and the factory~ Since the ` components are normally glued together, the replaced hearingaid must again be constructed using the same or similar 3S process that the first aid went through which may or may : - 2 -.
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not solve the original problem~ A few attempts have been made to create a standard hearing aid which fits most ears, however, the standard aid is normally round~ oval or eliptical in shape so that it can fit either earO The conical tip of such a standardized hearing aid often and frequently works its way out of the ear when the user eats, chews, yawns or talks.
~ dded to the complexity of providing a satis-factory hearing aid to a patient? are the various types of hearing losses which may occur. Because each patient . may~suffer a different type or frequency range of hearing loss the normal process includes hearing tests by an. audio logist who then "prescribe!s'i what the tester believes is . the best correction which again may have to go back and f.orth between the factory until the specific hearing loss is matched with the charac:teristics of the electronics of the heariny aid, ~hile~ it has probably been suggested that hearing aids could be massed produced for people with mild, moderate and severe hearing losses, due to the 20 complexity of the hearing mechan.ism in the human body an~ ' patient individualities, such hearing aids could only be marginally effective for a limited number of individuals.
In-the-canal type hearing aids are made possible because of the miniaturization of batteries and necessary electronic components. 'rhese miniaturized components are incorporated into a single ear mold to be worn in the . external ear, extending or penetrating into the auditory : . ~ canal o~ a userO Locating the hearing aid in the ear, rather than on the belt or behind the ear~ is preferred ~ 30 for acoustic reasons. The flap of the ear is shaped to : ~ be the primary sound gatherer of the human body. The crenu-lations of the ear are sound reflectors - they~assist the brain in identifying the direction of the soundO The head, itself creates by diffraction, a shadowing of certain sound:
which also aids in such localization of sounds. Another : , . . 3 .. , ~ . . ~ . :. , `` ~297~Z~

ad~antage of this type of hearing aid is derived from its ~mall size and, therefore, its inconspicuous cosmetic appearance. However, this advantage was previously thought to limit the production volume of in-the-can~l hearing aids because miniaturization makes mass production and quality control dificult~ Miniaturization has also limited the range of severity of hearing loss which can be effectively compensated for by in-the-canal hearing aids.
Generally, in-the-canal hearing aids are either individually fitted to the,user's ear by a cus~om molding process (U,S. Patent NoO 4,471,49Q), or are selected irom stock cylindrical canal aids having smooth polyvinyl sur-faces (U.S. Patent No, 3,852,5403, usually constructed of a dental acrylic material (methylmethacrylate)O Both lS o these methods have several disadvantages.
Individual fitting of the ear mold requires that an impression be made of the individual user's ear during a preliminary visi~ to ~he audiologist or hearing aid dis- ' penser. The impression i~; sent to a craftsman for individual molding of the earshell to match the user's right and/or left auditory canals, These molds are then assembled with predetermir,ed electronic components at the , factory and fitted in the user's ears during a subsequent visit to the dispenser's office. In addition to the need : ~ 25 for a~ least one subsequent visit, this method is uncom-fortable because of the necessity of making an ear impression. The method is also expensive and time consuming due to the shipping, handling and individual craftsmanship required in production of each individual ear mold.
Selection of prior stock canal aids did not achieve an accurate ~itting with the individual auditory canal of the user. Because stock canal aids conformed to standard requirements used in mass producing these aids, stock canal aids could not fit the individual shape of ~ 35 each auditory canal~ The cylindrical or eLiptical shape :

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, of the stock canal aids known in the prior art produced discomfort while wearing the hearing aid since it was not fitted to ~he individual ear canalO Also, the shape often resulted in the stock canal aid falling out of the ear ~S since there was nothing in the shape that would "lock"
the hearing aid into the ear canalO
The ear molds for stock canal aids of the past were manufactured in a cylindrical or eliptical shape so that the right and left ear molds were symmetrical and interchangeable. Recently, stock canal ear molds have added a single rearward bend to the basically cylindrical or elip~ical shape of the ear mold shellO However, the same shell is still used or the right and left canals by inverting the shell bei-ore adding the cover plate.
An oversized cover plate ~ith the adjustable volume control and electronic components are attached to the shell, The periphery of ~he cover plate is then carved down and buffed to match the shell. The result is symmetrical right and left ear molds that are unique only because the volume control rotates in a different direction in the left ear mold than in the right ear mold~
In both custom Ln-the-canal hearing aids and stock canal aids, the formation of the ear mold by perma~
nently attaching the cover plate to the shell creates serious problems in repai;ring and servicing these types of hearing aids. Since the electronic components are perma-- nently sealed within the ear mold~ the ear mold must be cut apart to service or replace any components which are defective. The replacement of defective electronic parts, for example, ~he microphone or receiver, may also alter ~; the response characteristics of the hearing aid. Thus, servicing or repairing in-the-canal hearing aids, particu-larly including warranty repairs, is an expensive process which cannot typically be done at the hearing aid dis-penser's store or office and which usually results in the .

, ~Z~3174;21 hearing aid performing very differently after it has been serviced at the factory. In fact, warranty repairs are the single larg st cost in the hearing aid industry~
resulting from the patient's dissatisfaction with the pre--5 scribed and custom manufactured hearing aid Ano~her drawback with both types of in-the-canal hearing aids known in the prior ar~ is:that the electronic components incorporated into these healiny aids are not specifically chosen by user selectionO Currently, most manufactllrers and hearing aid dispensers p.rescribe a certain combination of electronic components to be used in a hearing aid ~ased upon the graphic results of the patient's audio--gram~ The audiogram chart shows the resul~s of a hearing threshhold response or hearing acuity test performed by 15 an audiologist or hearing aid dispenser using an audio-meter~ The aud.iometer consists of a pair of receivers placed in the user's ear.s, usually in the form of a headset, which are connected to a tone generating device. The opera-tor varies the tones generated and inquires whether the patient can detect the generated tones at a variety offrequencies and amplitudes. The result of this process is that the hearing aid that the patient receives is not ~ased on the patient's selected preference for a combination : of electronic componentsO Rather, the components are usually selected from a prescription generated by the audiologist or hearing:aid dispenser on the basis of the ~;
audiogram and/or the patient's response to the acuity testsO
Additionally, each manufacturer has its own method for interpreting the prescription and the audiogram into ~ 30 a specific combination of electronic components that are :~ incorporated in the hearing aidO Complexity i9 added to the process because even the patient's own ear canal changes the prescription when the finished hearing aid is inserted into the patientls ear canal~ This is: due to acoustical -35 "resonant" interactions between the ear canal and the 6 ~

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characteristic sound output of the aid. The canal is a resonant chamber which will ~eact differently to different frequencies for different patients. In addition, different standing wave patterns may deYelop for different patients S depending on the frequency response of the aid and the patient specific spacing of the receiver and the patient's own eardrum, as well as ear canal geometry.
A few hearing aid dispensers use a master hearing aid device in an attempt to present simulations of different combinations of electronic components for a user to select among. With a typical master hearing aid~ the user is given a set of headphones connected through the master hearing aid to an external microphone or external noise source. In a random manner the user is then asked to express a preference amonc~ the various simulated combina-tions. In practice, howe~er, no master hearing aid achieves the goal of providlng a he!aring aid specifically chosen by user selection 7 Becau~;e a patient's hearing is tested on a device separate and clistinct from the hearing aid eventually given to the patient, the characteristics of the device the patient tested with and the device the patient eventually receives are different.
SUMMARY OF THE INVENTION
The present invention involves a mass produced automatable canal hearing aid capable of standardized fabri-cation which is designed 1:o overcome the above-identified problems in the prior art~ The microphone, receiver, ampli-fier, and battery used in capturing and amplifying the ~ sound waves received at the user's ear are all wholly - 30 contained within a prefabricated modular sound assembly ~;~ which snaps into a patient selectable prefabricated earshell assembly. The prefabricated earshell assembly is con-struc~ed from a hollow rigid body with a soft, resilient covering affixed to the exterior. The rigid body and ~; :

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covering have at least one opening to the patient's environ-- ment and at least one opening to the eardrumO The opening to the patientls environment is closed by a detachably interconnected cover module In the preferred embodiment, the prefabricated earshell assembly has a hollow rigid body of singular size and shape with a soft, resilient covering of one o~ a plurality of preaffixed shapes and thicknessesO The hollow rigid body has a generally D-shaped opening to the patient's environment with the curved portion oriented ~oward the back of the ear and a tapered portion narrowing to the opening to the eardrum and having a forward and inward hook and an upward twist. Thus~ thé right and left ear-shell assemblies, although mirror images, are unique and non-interchangeableO
The cover modul~3 houses the microphone, amplifier and battery ~ource and is flexibly connected with the receiver. Both the recei~er and the microphone are encased in a cushion to minimize mechanical vibration feedback.
The battery source is removably housed in a pivotally mounted battery compartmentO A rotational volu~e control mounted on the cover moduLe and connected to the amplifier allows the user to adjus~ the gain of the hearing aid The cover module is detachably interconnected with the rigid body such that a key must be engaged with the cover module and rigid body before they may be disconnected~
Additionallyl the rigid body and softl resilient covering may be provided with vent channels for allowing ~ air to by-pass ~he hearing aid and circulate to the ear-- 30 drum. This vent system is selectably closable at the D-shaped opening in~accordance with the user's preference or the amount of~feedback generated. The degree of venting may be patient selected to make use of residual hearing, particularly of low frequency sounds. And the patient selected size of the vent can provide useul modifications -~ 8 -.

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of performance characteristics~ such as reducing unwanted low frequency noise emphasis from the hearing aid In an alternative embodiment, the detachable cover module is replaced with a test module to be used in the evaluation and selection of the specific electronic co~ponents -to be inserted into the earshell assemblyO
A tes~ r~ceiver is inserted into the earshell assembly fitted to the user's auditory canal and is connected to the test module. The test module is umbilically connected to a test station which can simulate various combinations of the electronic components that comprise the hearing aid. By using the same earshell assembly that the user will receive, the test moclule allows the user to select the best set of electronic! components for the hearing aid through a paired comparisc~n process similar to that used in ophthalmology, The principal objectives of the invention are:
(a) to provide a user selected hearing aid that is mass produced and still conforms to the individual shape of .
a user's auditory canal; Ib) to provide a hearing aid that ~`is composed of electronic components which are user ; ~~ selected; (c) ~o provide a hearing aid that may be tested - and fitted during a single visit to an audiologist or `~hearing aid dispenser; (dl to provide a hearing aid~which minimizes mechanical vibration and acoustical feedback;
and (e) to provide a hear:Lng aid with a removable but lock-able cover module. These and other advantages and obliga-tions will become obvious to those skilled in the art upon a review of the ollowing description of the preferred 30 ~embodiment and the accompanylng drawings.
;BRIEF DESCRIPTION OF THE DRAWINGS
Fig. l is a horizontal cross-sectional~view of the interior of the hearing aid according to the present invention showing the components thereof.

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Fig. 2 is an exploded version of the horizontal cross-sectional view depicted in FigO 1 showing the inter-relation among the various elemen~s.
Fig~ 3 is a topographical end view of the cross sectional profiles at regular intervals in depth of field, ~, illustrating a computer generated con~our identifying design criteria related to the rigid core assembly based on anatomical and engineering input to accommodate the average human auditory canal.
Fig. 4A is a side view of the rigid core and flange for the left auditory canal.
Fig. 4B is a front view of the rigid core and flange for the left auditory aanal.
Fig~ 5 is an end view of the cover module~ without lS microphone, battery compartment or volume control.
Fig~ 6 is an en~ view of the test module as seen from outside the ear.
Fig, 7 is a perspective view of the removal key for the cover or amplification module.
Figs. 8A, 8B and 8C are top, si-de and interior end elevational views, re~;pectively, of the left earshell assembly depicting various shapes and thicknesses of the , flexible covering, Fig~ 9 is a perspe¢tive view of the removable ~ , 2S battery compartment.
Fig. lO is a schematic of the electronic co~po-nents of the hearing aidO
' Fig~ 11 is a top view of the flexible substrate.
Figs. 12A and l~B are top and side views of the 30 , flexible test module substrate, microphones and receiver.
Fig, 13A is a pictorial view of~a representative variety of the variable plas~ic vents attached to a bar '~ by break-off connections that can be used with the invention to control the amount,of venting and consequent acoustic - 35 response of the aid. Fig. 13B is a cross-sectional detail ' .
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though part of the earshell assembly and part of the vent piece to illustrate the way it is retained.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The ear canal (external auditory meatus~ leads from the concha to the eardrum, and varies in both size and shape. The outer portion of the~canal~ about one-third of its length, is cartilagenousO The remaining two-thirds is bony. The canal is not straight, it is irregular in course. It takes on a somewhat S shaped form medially.
; 10 It curves first anterosuperiorly (first bend-forward and up~, then posterosuperiorly (second bend-backward and up) and Einally anteroinferiorly (forward and down)O It is for this reason that the pinna must be pulled up and back in order for one to see the eardrum, lS As would be expected from its irregular course, the length of the canal i~3 also not uniform. Instead, it is normally over two centimeters long posterosuperiorly and normally slightly over three centimeters long inferoanteriorly. Also contributing to the greater length 20 of the lower part of the ~anal is the oblique orientation J
of the eardrum as it sits in its annulus at the end of the canal.
- As bes~ seen in~Figures 1 and 2, the preferred embodiment of the present invention includes a mass produced heariny aid 10 capable of being inserted into the external auditory canal or meatus of the ear of a user (not~shown).
The preferred embodiment of the invention accommodates, in unique and creative ways, the physiological attributes of the human hearing mechanismsO The hearing prosthesis 3~ 10 has been human engineered to respond to the different characteristics of different patients, creatively sculpted - to respond to shape and to address interfacing between an engineered solution and the physical reality of different~
human ear canals. Finally, the choice as to the best solu-tion or configuration of these factors is left to the only ~: .
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individual who can accurately judge and d~termine the bestsolution and configuration, the patientO
The physical characteristics of the ear are accommodated by a solid core or shell 20 which is charac-S terized by a deeply sculpted forward and inward hook 13to accommodate the first bend between the concha and the meatus. ~herefore all but the control plate 99 or the amplification module 101 penetrates into the canalO The core 20 then penetrates the canal with an upward twist~
- 10 shown in Figures 4 and 8, to conform to the natural anatomy of the ear. Fixedly secured ~o the outer surface of the core 20 is one of a plurality of soft conforming layers 3ba-30e, shown in Figures 8A-8Co These elementsl the core 20 and one of the pluralit:y of coverings 30a-e, and a flange 40 to retain the cover lOt~ for the amplification module 101/ constitute the patierlt selected earshell assembly 12. The specific choice c)f which layer 30 to use depends on the specific size of the patient's ear canal, the patient's comfort and the sound characteristics of the 20 aid 10. The patient selec:ted soft malleable layer 30 conforms to the surface, cliameter and shape o~ the external auditory mea~us and penetrates toward and perhaps to the ; second bend. Since the last two ~hirds of the canal are bony, this is where physic:al discomfort is most likely to occur. The soft material conforms to the surface, to seal feedback pockets, ancl does not force its shape on the ear canal. If penetration is too deep for some reason, the tip 38 can be easily c:ut or shortened by the dispenserO
Using the patient selected earshell assembly 12, a test m dule 200 shown in Figure 6, is inserted which ;
; ~ ~ is connected to a test device uslng the same electronics - 60 shown in Figure~lO~that will be presen~ in the final hearing aid 10. The patien~, then, using a decision tree and test procedure, chooses personally the electronic characterist}cs of the aid 10 which best assists the ~ .

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12974~'1 patient's hearing loss or hearing problem. The method or process of selection of the electronic components during selection of the aid 10 is more fully described in CanadianPatent Application Serial No. 537,802, entitled Patient Controlled Master Hearing Aid filed contempora-neously herewith. An amplification module 101 having these exact patient selected components 60 is then snapped into the patient selected earshell assembly 12 and the patient can leave with his or her own uniquely designed and matched hearing aid 10.
In the event that a condition is experienced which was not anticipated during the test, either physical discomfort or a sound response anomaly, either the earshell assembly 12 or the amplification module 101 having electronics 60 can be easily exchanged or replaced with the use of a simple tool 150 is shown in Figure 7.
The invention is achieved as follows:
The hearing aid 10 includes an earshell assembly 12 for housing the standard electronic components usually found in a hearing aid: microphone 90, amplifier 60, receiver 70 and battery source 80. A special microphone 90, a pseudo random frequency noise generator is used if the hearing impediment is tinnitus, a "ringing" or "buzzing"
in the head. The electronics 60 are mounted in and to an amplification module 101 which consists of a cover 100, the elec.ronic components 60, including a flexible substrate 66 upon which certain of the components are surface mounted, including the amplifier 60, capacitors Cl-C4, resistors Rl and R3, and which extends to the microphone 90, all of which are shown in Figures 1, 2 and 11 and schematically in Figure 10. The amplification module 101 is detachably connected to the earshell assembly 12 as will be described in more detail below.

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Earshell assembly 12 is inserted into the auditory canal of a user's ear with receiver 70 oriented toward -the eardrum and microphone 90 oriented toward the patient's en~ironment. In position, hearing aid 10 rests within -5 - the auditory canal of the user with the opening of the concha bowl of the user's ear filled by that portion of earshell assembl~ 12 which faces the environment, As seen in the drawings, earshell assembly 12 is formed from a hollow rigid core 20, a soft~ resilient coveriny 30 affixed to the exterior of the rigid core 20, and a rigid flange 40 attached to the environmental end 22 of ~he rigid core 20. Earshell assembly 12 is also provided with openings 24" 34 in the core 20 and covering 30 respectively to the eardrum. The environmental ends of the core 20 and covering 30 have corresponding openings 22 and 32 respect1velyO ~'over 100 is detachahly inter-connected with 1ange 40 ~3uch that it substantially closes opening 22 to the environlnentO The elements forming ear-: shell assembly 12 are pre:cabricated in a shape and manner to be fully described hereinafter.
Earshell assemb.Ly 12 houses all of the electroniccomponents of he~aring aid 10. Microphone 90 is connected as part of ampli i.cation module 101 with the sound receiving portion of ~icrophone 90 protruding through aperture 102 o~ cover modu~e ~00. The portion of microphone 90 housed in cover module 100 is encased in a cushion 92 tsuch as shown in Figure 12j to minimize mechanical vibration feed-back pickecl up by microphone 90, Amplifier 60 on flexible substrate 66 i5 electrically connected to microphone 90 and~battery 80. ~E'lexible connection 62 carries the ampli-fied signals to receiver 70 with loop portion 64 providing strain relief between cover module 100 ana receiver 70.
: Like microphone 90, receiver 70 is encased in a cushion 72 to minimize mechanical vibration feedback.
Cushion 72 is provided with an extraction tab 73 and an . - 14 ;.... .. ~ ~ ~

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annular flange 74 allowing tubular segment 76 to be extended through opening 24 of rigid core 20. Cushion 72 and receiver 70 are thereby secured in earshell assembly 12 in a grommet-like fashion and can easily be removed, if necessary, with use of the extraction tab 73O
Batt.ery source 80 is removably housed in the cover 100 by battery compartment 82i shown in Figure 9.
Battery compartment 82 is also removable and is pivotally mounted in cover module 100 on pivot pin 108 and extends through aperture 104 of cover 100 in a manner to be fully described hereinafter. Volume control 120 is rotationally housed in cover 100 and e~:tends through aperture lQ6.
Volume control 120 is electrically connected with amplifier 60 and includes raised flanges 122 and 124 for aiding in it~ rotati~nal opexation by the userO
E'ig. 2 shows an exploded view o earshell assembly 12 and the interrelation among the various elements there-of. Beyinning on the left: of Fig. 2, it can be seen that annular seating surface 3~i of covering 30 will abut inner .
surface 25 of rigid core 20 to prevent core 20 from passing through inner opening 34 of:covering 30~ In a similar fashion, neck 78 of receiver 70 is prevented by annular :
seatiny surface 26 from passing through inner opening 24 of rigid core 20. Annular. flange 28 of rigid core 20 mates with annular groove 42 to seal the periphery of opening 22 when flange 40 is connected with rigid core 20 On the outer side of flange 40, bottom annular ridge segment 48 abuts collar 106 when cover module 100 is detachably interconnected with flange 40O Annular ridge segments : 30 46, 50 and 52 (shown:in Fig. 4B) also abut collar 106.
During prefabrication, soft~ resilient covering 30 is fixedly attached to the exterior of rigid core 20 and flange 40 is fix~dly attached to opening 22 of rigid core 20.
Since t~. outer periphery of ~he inner edge Qf flang~ 40 3S overhangs the sleeve 30, it protects the edge o the sleeve . , .

Z97~21 30 from peeling off the core 20 when the amplification module 101 is snapped onto the earshell assembly 120 Tubular segment 38 surrounding opening 34 allows ~ .
tip 38 of the aid to be Pxtended further into the ear ca~al o the userO This is desirable since the closer the orifice of tub~lar sec~ment 38 is to the eardrum, the greater the effective sound output of hearing aid lOo Roughly, as ~he distance between the receiver and ~he surfa~e of the eardrum is halved, the effective sound pressure of the hearing aid is doubled (iOe., increased by 6 dB gainj.
Con~entional in-~he-canal hearing aids penetrate only 1/4 to 3/8 of the length of the auditory canalO Further penetration by prior art devices is prohibited by ~he pain associatea with a hard object being inserted into the auditory canal. Since covering 30, including all of tubular segment 38, is made of a ~oft, resilient material, tubular segment 38 may penetrate up to 3/4 o the length of the auditory canal, ~hereby increasing the effective gain of hearing aid 10 by upward of 6 to 10dB over conventional .
~: 20 in-the-canal hearing aids. This gain is accomplished with ~ . l out requiring any corresponding increase in the power : consumed by the device.
:: The elements involved in detachably intercon- :
. nectlng amplifica~ion module 101 with flange 40 are shown 25 in Fig~ 2/ 4 and S a When cover 100 is aligned and brought .
into contact with flange 40, the four bayonet tabs 110, 112, 114 and 116 on the inner side of the cover 100 align wi~h and slide along the inner surface of retention tabs 50 and 52 on the periphery of flange 40O The bulbous ends 30 :of bayonet tabs ll0, 112, 114 and 116 cooperate wi~h the ; raised portions o retention tabs 50 and 52 to prevent the disconneetion of cover module 100 unless re~.o~al key 150 is used in a manner as described hereinafterO As bayonet tabs 110, 112, 114 and 116 are slid along the ridges 35 50, 52 they press outwardly against ridges SO and 520 . . :

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Since tabs 110, 112~ 114 and 116, flange 40 and integrally molded ridges 50 and 52 are made of a rigidly resilient material, like plastic, the tabs deform inwardly and/or the ridges deform outwardly to allow cover module 100 to be inserted into flange 400 Once the bulbous portion of bayonet tabs 110, 112~ 114 and 116 are driven inward past the raised portion of ridges 50 and 52, the tabs 50, 52, 110~ 112~ and 116, return to their original position and lock cover module IOO to flange 40, by retaining the ends of the tabs in apertures 48, thereby preventing cover - module 100 from being outwardly removed due to the pressure of the ridges 50, 52 on the ends of the bayonet tabs, As shown in Fig.. 5 and Fig. 9, battery compartment 82 for battery source 80 i.s pivotally mounted on pivot pin 108 at plvot channçl 84 suah that it may be horizontally swung ~hrough aperture lO~l until the positive and negative contact surfaces on battery source 80 fully engage positive contact 86 and negative contact 88 in cover module 100.
: Positive contact 86 and negative contact 88 are metallic plates with rounded contact points 87 and 89 respectivelyO
The contact plates 86 and 88 are integrally molded into ~ . the plastic body of the cover 100 with the rear portion : ~ of the plate extending ou1ward ~rom cover module 100.
- This allows contact plates 86 and 88 to slightly depress 2S respectively downward and upward against the positive and . negative contact surfaces of battery source 80 as it is slid across contact points 87 and 890 The pressure exerted - by contact plates 86 and 88 and contact points 87 and 89 ~: frictionally secures battery source 80 in cover module 100~ provicing good electrical connectlon with the positlve : ~ and nega~ive cont~ct surfaces of battery source 800 The : battery CO- par m~nt lS restrained by a snap mechanis~.
. The snap mechanism prevents battery compartment 82 from ~ swinging out from cover module ioo until battery compartment : 35 tab 85 is used to pivotally swing battery compartment 82 . ~ , ;
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out through aperture 104. Once fully swung out from aperture 104, battery compartment 82 may be disconnected from cover module 100 by unsnapping pivot channel 84 from pivot pin 108 thereby removing battery compartment 82 and opening aperture 104. Battery source 80 is prevented from falling out of battery compartment 82 by lower annular lip 83.
A schematic of the electronic components 60 used in the amplification module 101 is shown in Fig. 10. The parameter values for the sound source 90, one of two micro-phones 210 or 212 shown in Figure 12 or a tinnitus random noise source, the input coupling capacitor C2, the gain resistor Rl and the maximum sound output resistor R4 are patient selected using the test module shown in Figures 6 and 12. A variable resistor R2, the receiver 70, ampli-fier 60, battery source 80 and bypass capacitors Cl and C4 are standard components used in the aid 10. These electronic components 60 are connected to or surface mounted on a flexible substrate 66 as shown in Fig. 11. The flexible substrate 66 is made of a polyimide material.
The space occupied by the electronic compo-nents 60 is minimized when substrate 66 is flexibly inserted ; into cover module 100. Also, flexible connection 62 connects amplifier 60 and receiver 70, providing a connection that vibrationally isolates amplifier 60 from receiver 70. The extraction tab 73 serves the purpose of providing a means for removing receiver 70 from opening 24 where it is secured in a grommet-like fashion.
~ The cover 100 is detachably disconnected from flange 40 by inserting removal key 150, as shown in Fig.
7, into aperture 104. Removal key 150 is provided with two independent key means, lever end 152 and shovel end 160. Lever end 152 is inserted into aperture 104 by hooking notch 155 onto the middle of piyot pin 108 so that prong 156 lS positioned between bayonet tabs 112 and 116. Lever -` ` ` 12974~21 end 152 is then pivoted about nvtch 155 so that prong 157 is similarly positioned between bayonet tabs lI`0 and 114.
Lever end 152 is pushed into rigid core 20 and prongs 156 and 157 are expanded out~ard by the operator of the removal key squeezing together levers 158 and 159 in a clothes-pin-like fashionO Prongs 156 and 157 press outwaxdly against ridges 50 and 52, thereby allowing the bulbous portions of bayonet tabs 110, 112~ 114 and 116 to pass over the lip portion of ridges 46, 48t 50 and 52 Cover module l00 is now free to be disconnected by pulling outwardly on cover module 100. Once cover module 100 has been detached, receiver 7C~ is released by a slight tug on extraction tab 73 on c~shion 72 to disengage the grommet-like connection o~ annular flange 74. All of the lS electronic components may then be removed easily from ear-shell assembly 12.
Earshell assemb]y 12 is also preferably provided with vent channels 130, 1:12 and 1330 The vent channels allow air to bypass the ampIifying portion of hearing aid 10 and circulate ~o the eardrum. The use of appropriate vent inserts 134a-134e minimize the accoustical feedback experienced by the user. The vents 130, 132~ 133 as ~ restricted by the inser~s 134 prevent the discomfort and feeling of ~ullness usual:Ly associated with the insertion 2S of the object into the auditory canal. While it is seen in the preferred embodiment that vent channels are formed - ~ by the combination of rigid core 20 and resilient covering30, it is also possible to form the vent channels by other methods, such as providing channels internal to rigid body 30 2b or providing a passage completely within resilient covering 30.
As best shown in Figs. 4A and 4B and Figs. 8A
and 8B, U-shaped vent channels 130 and 132 are formed in the valleys created by center strut 136 and side struts 135 and 137 located on the inferior side of rigid core .
, . . .
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297~21 20. Side struts 135 and 137 are approximately the ~,ame height as center strut 136. Near opening 22 rigid core 20 is also provlded with a second center strut 138 of a similar heiyht as center strut 136~ to assist in forming vent channels 130~ 132, and 133 on that portion of the inferior side of rigid core 20 which broadens toward the outer ear. When resilient coyering 30 is affixed to the exterior of rigid core 20~ it can ~e seen in Figs. 8A and 8B that vent channels 130 and 132 are created beginning at the opening to the inner ear and extendiny along the inferior side o~ earshell assembl~ 12 to vent channel openings 130, 132., and 13.~ to the environment.
Vent channels 130, 132, and 133 may also be selectably closeable at the bottom of opening 22 to the environment with the use ~f vent inserts 134a ~ 134e.
The vent insert~ 134a - 134e are preferably available to the dispenser on a vent,tree 150 to provide a range of venting from no vent usin~ insert 134a to full open using no vent însert 134, althol~gh maximum venting is perferably achieved with the largest apert~red 133e vent insert 134e.
Each of vent insérts 134b - 134e have successively larger apertures 133b - 133e to accommodate the user's preferenceO
The amount of opening 133 left in the vent channel is selected in accordance wi'_h the user's preference as to sound quality and minimiz;ltion of acoustic feedback. Side-ways D-shaped opening 144 at the bottom of opening 22 is formed by the combination of bottom cross member 140 and bottom annular ridge 48. Opening 144 may be fitted with .

any of the various sized vent closures 134 as shown in 30 Fig. 13B. Vent closures 134 are selected and pressably inserted into opening 144 until the vent closure abuts the outer edges of center struts 136 and 138 and are retained by a snap interlock 152 in aperture 151 in the top of the vent inserts 134O
In an alternative embodiment of the invention, - 20 ~

LZ974~1 cover module 100 i5 replaced by test module 200 as shown in Fig. 6. Test module 200 includes test microphones 210 and 212 and umbilical connection 230. As shown in Fig.
12, test microphones 210 and 212 are electrically connected to test receiver 220 by flexible connection 216 which serves as a strain relief strapO Like microphone 90 and receiver 70, test microphones 210 and 212 and test receiver 220 are encased respectively in resilient cushions 211, 213, and 2~1. Tes-t receiver cushion 221 is provided with annular 10 : flange 222 and elongated tubular segment 224 for inserting test receiver 220 and cushion 221 into inner opening 24 and 34 in 2 grommet-like manner~ Test microphone cushions 211 and 213 are also provided with annular flanges 214 and 215 and tubular segme~ts 216 and 217. When cushions 211 and 213 are inserted .into apertures 202 and 204 of test module 200, tubular segments 216 and 217 extend through apertures 202 and 204 wit:h cushions 211 and 213 and test microphones 210 and 212 thereby secured in a grommet-like manner. .
Like cover module 100, test module 200 is also detachably interconnected with rigid core 20 and flange ~; ~40. In the preferred emb~diment, because of the location - o~ test microphones 210 and 212, removal key 150 may not be used in a manner similar to the unlocking of cover module 100~ Therefore, shovel end 160 is provided on removal key 150 with prongs 162 and 164 to be inserted into slots 240 and 242 of test module 2000 Unlike cover module 100, : the collar segments abutting annular ridge segments 46, : ~ : 48, 50, and 52 are split into three collar segments 244, 246, and 248. Slots 240 and 242 are created by the spaces between collar segments 244 and 246 and collar segments : 244 and 248. When shovel end 160 of removal key 150 is inserted into slots 240 and 242, prongs 162 and 164 press outwardly against ridges 46, 48, 50 and 52. Since flange . 35 40 and integrally molded ridges 46, 48, 50 and 52 are made - 2~ - :

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1~974;Z~L :
of a rigidly resilient material, like plastic, the ridges deform outwardly to allow test module 200 to be removed from flange 40.
~mbilical connection 230 provides electrical connection between test receiver 220, test microphones 210, 212, and the external test device ~not shown, but described in co-pending Application Serial No. 537,802) which is used to simulate the various combinations of electronic components to be inserted into hearing aid 10.
Umbilical connection 230 is moldably secured in test module 200 and is formed~of a flexible material.
One of the objectives of the invention is to provide a hearing aid that is mass produced, but still generally conforms to the individual shape of each user's auditory canal. The invention discloses several inventive features for accomplishing this objective. As previously described, the soft, resilient covering 30 that is af~ixed is the exterior of rigid core 20 allows the cylindrical or elliptical shape of the in-the-canal aid to more easily conform to the individual variations in a user's auditory canal. Other inventive features which assist in accom-plishing this objective are disclosed in the results of independent research into the average shape o, and common-alities among human auditory canals. The results of this research are summarized and shown in Fig. 3. The engineered result of Figure 3 was then further refined by creative sculpting and empirical testing to produce hook 13 for the shell and the variations in dimension for the sleeve 30a - 30e shown in in Figures 8A - 8C. The dimensional values are set forth in those figures are belleved to accommodate approximately 95 percent of the population to provide a comfortable fit within the canal and a sealing interface between the skin and the sleeve 30.
The inventive features disclosed by 3, 4 and ; ~ 35 8 and by this inventlon are not taught by the prior art.

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1297421:

While custom molded in-the-canal hearing aids known in the prior art convey some of the same information as found in Fig. 3, they do not teach a least common norm for the shape of an in~the canal hearing aid~ Nor does this prior art suggest a range of variations about such a normO The ~;~
prior art for stock canal aids and for receiver tips encased in soft, resilient coverings teaches that auditory canals conform to a cylindrical shape or to an elliptical shapeO
A rectanyular shape for a resilient covering is disclosed by U.SO Patent No 3,527 901. A circular tubular shape for a resilient ear tube sleeve with a single rearward bend is disclosed by U.SO Patent No. 4,375,016. An ellip-tical shape, is disclosed by U.S. Patent No. 3,783,201, is in the form o a super--elipse defined by the equation (x/a)n + (y/b)n - 1, wherein n=2.4. None of these shapes teach the inventive features disclosed by this invention.
The inventive features taught by the research summarized by Fig. 3 and modified by the designs disclosed in this invention are: The D-shaped opening of the auditory canal to the outer ear or:iented with the curved portion toward the back of ~he ear (shown at A); The U-shaped opening to the inner ear oriented with the curved portion ~ to the bottom of the ear tshown at B); The tapered portion having a forward and inward hook and an upward twist (shown at C and D); The combination of the above features such that earshell assembly 12 is unique and non-interchangeable for the right and left auditory canals of a user; and the plurality of shapes and thicknesses of covering 30 designed to accommodate specific ranges of variations from the least 30 common norm as shown in Figs . 8A, 8B and 8Co -Although in the followin~ preferred structure and operation of the invention all of the inventive features are used in combination it will be observed that the inven-tive features may be used individually or in any combination to achieve the objective of the invention of providing ' -' ., :
.

lZ9742S;

a better fitting mass produced hearing aidO
Referring now to FigO 4A and 4B it can be seen how these inventive features are i~corporated in the mass production hearing aid as described aboveO Fig. 4A and 4B show ~he rigid core 20 and flange 40 fsr the left auditory canal of a userO The D~shapecl opening to the outer ear is shown at 42. The U-shaped surface facing the eardrum is shown facing the viewer at 135, It is observed that the inverted U-shaped.vent channels 130 and 132 combine with the interior of the auditory canal near : the eardrum ~o form a seal having a U-shaped outline which . :~
conforms to interior shape of the ear canal~ The:forward and inward hook one upward ~wist are apparent in many of the Figures, such as Figs, 1, 2, 3, 4 and 8. As indicated lS in Fig. 8 the forward and inward hook is approximately 45 (Fig. 8B) with an upward twist of approximately 8 from horizontal (Fig. 8A). The resulting nominal twist ~rom vertical is approximately 5 (Fig. 8c). It will be understood, however, that due to the resilient nature of the sof~ sleeve 30 that these angular displacements may . : . and will vary to assume t:he natural hook, twist and tilt naturally occurring in the patient's own ear canal. T~e : ~ plurallty of shapes and thicknesses of the resilient : covering 30 are best shown in FigsO 8A, 8B and 8Co The - 25 resulting tip sizes become ovoid in shape with the following dimensional variations~

.
SLEEVE SIZE a x b r ' (+.015) '-,:
30a 1 230 x 330 OlOOr :: 30b 2 260 x 360 ~150r .

~Z~742~ ~

30c 3 290 x 390 .200r 30d 4 320 x 420 l250r :
- 30e 5 350 x 450 ~300r , :.
The resulting core 12 design with a substantial S hook 13 permits the aid 10 to be inserted deeply within th concha and the core shape is conducive to the upward and inward course of the ear. ~he soft materials of the sleeve 30 adhere to the skin better than plastic surfaces used in the past and a good acoustic seal has been achieve~
for all sizes of the aid 10. The malleable and flexible material o the sleeve al~io conforms to the contours of each patient's ear to ena}~le deep penetration and better perormance without pain or discomfort.
The unique shape and combination of the inventive lS features of this invention are necessary because the ~ ;1 in-the-canal hearing aid :lO disclosed by this invention extends further into the auditory canal than other in-the-canal aids ]cnown in the prior art~ Previou :
in-the-canal aids did not reach or extend beyond the second 2~ bend that is present in the auditory canal~ This second bend requires that a hearing aid inserted to this point have a flexible canal tip to accommodate the second bendO
While the forward hook of the first bend in the auditory canal is taught by the prior art, none of the prior art teaches how to form a~ in-the-canal hearing aid which can accommodate to the second bend in the auditory canal.
It will be obvious to one skilled in the art that a number of modifications can be made to the specific embodiments described herein without essentially changing ; 30 the invention. The amplification module and test module " - : .
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may be detachably interconnected with the rigid core by means other than the bayonet tabs shown, and the battery compartment and replaceable battery source may be imple-mented in a number of different waysO ~ccordingly, whil.ç
the preferred embodiment of the invention has been described and illustrated~ it ls understood that the invention is not limited to the precise construction herein disclosed, and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.
Having thus defined our invention, we claim.

~, ~ 26 -. .
,

Claims (51)

1. An auditory canal hearing aid to be wholly inserted within the external ear of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising:
a preassembled amplification module comprising:
a cover module having at least one aperture therein;
a sound source located within the aperture of the cover module;
amplifying means for amplifying the sound from the sound source;
a receiver for reproducing the sound amplified by the amplifier;
means for housing a battery source for supplying power to the amplifier, and means for interconnecting said sound source, said amplifier, said battery and said receiver means; a prefabricated earshell assembly comprising:
a precast and preshaped hollow thin shelled rigid core having at least one opening to the environment and at least one opening to the eardrum and having an external shape which conforms to the natural anatomy of the ear; and a premolded soft, resilient, malleable covering fixed to the exterior of said rigid core having a tip which extends beyond the eardrum end of the rigid core, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal; and means for detachably connecting the amplification module to the prefabricated earshell assembly.

2. The invention as recited in claim 1 wherein said rigid core includes interlocking means located adjacent said opening to the environment.

3. The invention as recited in claim 2 wherein said opening in the rigid core to the environment has a predetermined cross-section and wherein said cover module comprises:
a cover having a cross-section corresponding to the cross-section of said opening in the rigid core to the environment; and interlocking means located about the periphery of said cover such that said interlocking means of said cover to detachably interconnect said rigid core with said cover module.

4. The invention as recited in claim 3 wherein said cover module further includes battery retaining means for replaceably housing said battery source.

5. The invention as recited in claim 3 wherein said sound means is a microphone and wherein said cover module further includes microphone retaining means for housing said microphone means.

6. The invention as recited in claim 1 wherein said hollow rigid core comprises an expanded portion opening to said environment and, a tapered portion, extending toward the user's eardrum.

7. The invention as recited in claim 6 wherein said tapered portion of said rigid core has a forward and inward hook and an upward twist.

8. The invention as recited in claim 1 wherein said soft, resilient covering comprises a hollow shell having at least one opening to the environment, a tapered portion, and at least one opening to the eardrum.

9. The invention as recited in claim 8 wherein said opening to the environment of said hollow shell is generally D-shaped.

10. The invention as recited in claim 8 wherein said tapered portion of said hollow shell has a forward and inward hook and an upward twist.

11. The invention as recited in claim 8 wherein said hollow shell for a particular patient is selected from one of a plurality of hollow shells having varying thicknesses and shapes.

12. The invention as recited in claim 1 wherein said rigid core further includes vent means incorporated in the structure of said rigid core for allowing air to circulate from the environment to the eardrum.

13. The invention as recited in claim 12 wherein said vent means includes strut segments on the inferior side of said rigid core whereby said strut segments cooperate with said resilient covering to form a channel from the eardrum to the patient's environment.

14. The invention as recited in claim 14 wherein said vent means is selectably closeable at said opening to the outer ear in accordance with user preference.

15. The hearing aid of claim 12 wherein said vent means comprises a selectable one of a plurality of vent inserts, said vent inserts being interposed in the rigid core to restrict the flow of air therethrough, and each of the vent inserts having different apertures therein.

16. The invention as recited in claim 4 wherein said battery retaining means include a metallic negative contact plate, a metallic positive contact plate, and a metal pivot pin such that said negative contact, said positive contact and said pivot pin are molded integrally with said cover module.

17. The invention as recited in claim 5 wherein said microphone retaining means includes a soft, flexible cushion disposed between said microphone and said cover module.

18. The invention as recited in claim 1 wherein said amplifying means includes an amplifier and a flexible substrate material upon which said amplifier is mounted.

19. The invention as recited in claim 1 wherein said receiver means is encased in a removeable soft, resilient cushion.

20. The invention as recited in claim 19 wherein said receiver cushion is composed of two generally tubular segments, the first tubular segment housing the receiver means, and a second smaller diameter tubular segment extending from the sound emitting aperture of said receiver means for carrying the amplified sound to the user's eardrum.

21. The invention as recited in claim 19 wherein said receiver cushion further includes an annular grommet flange circumscribing the exterior of said receiver cushion such that said receiver means and said receiver cushion may be detachably secured in said rigid body by said annular grommet flange.

22. The hearing aid of claim 1 wherein the sound source comprises a pseudo-random noise generator for masking tinnitus.

23. The hearing aid of claim 1 wherein said rigid core further includes vent means incorporated in the structure of said rigid core, said vent means comprising a selectable one of a plurality of vent inserts, said vent inserts being interposed in the rigid core to vary the accoustical response of the vent means and each of said plurality of vent inserts having a different aperture therein.

24. An auditory canal hearing aid to be wholly inserted within the external ear of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising:
a preassembled amplification module comprising:
a cover module having at least one aperture therein;
a sound source located within the aperture of the cover module;
amplifying means for amplifying the sound from the sound source;
a receiver for reproducing the sound amplified by the amplifier;
means for housing a battery source for supplying power to the amplifier; and means for interconnecting said sound source, said amplifier, said battery and said receiver means; and a precast and preshaped hollow thin shelled rigid core having an expanded portion with a generally D-shaped opening to the environment and a tapered portion with at least one opening to the eardrum and having an external shape which conforms to the natural anatomy of the ear; and a premolded soft resilient covering fixed to the exterior of said rigid core; and means for detachably connecting the amplification module to the prefabricated earshell assembly.

25. The invention as recited in claim 24 wherein said means for detachably connecting the amplification module comprises a generally D-shaped annular flange attached to the periphery of said opening to the environment of said rigid core.

26. An auditory canal hearing aid to be wholly inserted within the external ear of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising:
a preassembled amplification module comprising:
a cover module having at least one aperture therein;
a sound source located within the aperture of the cover module;
amplifying means for amplifying the sound from the sound source;
a receiver for reproducing the sound amplified by the amplifier;

means for housing a battery source for supplying power to the amplifier; and means for interconnecting said sound source, said amplifier, said battery and said receiver means; and a prefabricated earshell assembly comprising:
a precast and preshaped hollow thin shelled rigid core having at least one opening to the eardrum and having an external shape which conforms to the natural anatomy of the ear and wherein said rigid core includes a surface facing the eardrum having said opening to the eardrum therein, said surface having a generally U-shaped outline with the curved portion of said outline oriented downwardly;
a premolded soft resilient covering fixed to the exterior of said rigid core; and means for detachably connecting the amplification module to the prefabricated earshell assembly.

27. An auditory canal hearing aid to be wholly inserted within the external ear of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising:
a preassembled amplification module comprising:
a cover module having at least one aperture therein;
a sound source located within the aperture of the cover module;

amplifying means for amplifying the sound from the sound source;
a receiver for reproducing the sound amplified by the amplifier;
means for housing a battery source for supplying power to the amplifier; and means for interconnecting said sound source, said amplifier, said battery and said receiver means; and a prefabricated earshell assembly comprising:
a precast and preshaped hollow thin shelled rigid core having at least one opening to the environment and at least one opening to the eardrum and having an external shape which conforms to the natural anatomy of the ear;
a premolded soft resilient covering fixed to the exterior of said rigid core; and wherein said rigid core further includes vent means incorporated in the structure of said core for allowing air to circulate from the environment to the eardrum including four strut segments on said inferior side of said rigid core whereby said strut segments cooperate with said resilient covering to form a channel from the eardrum to the patient's environment, said strut segments integrally molded to said exterior of said inferior side of said rigid core, said inferior side having anterior and posterior edges, including:
a single center strut running along the length of the spine of said inferior side of said rigid core;

an anterior side strut the same height as said center strut running along the length of the anterior edge of said inferior side of said rigid core;
a posterior side strut of the same height as said center strut running along the length of the posterior edge of said inferior side of said rigid core; and a second strut of the same height as said center strut extending a portion of the length of said inferior side from an intermediate location to the end of the core having said environmental opening and equidistantly spaced between said center strut and said posterior strut and running parallel to both;
whereby said struts form two U-shaped channels on said inferior side at the eardrum end of said rigid core and form three U-shaped channels on said inferior side at the environmental end of said rigid core such that said channels cooperate with said flexible covering to form a passage from said opening to the eardrum to said opening to the environment allowing air to circulate therebetween;
means for detachably connecting the amplification module to the prefabricated earshell assembly.

28. An auditory canal hearing aid test device to be inserted in the auditory canal of a user comprising:
a hearing aid shell assembly which is prefabricated from module elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid assembly comprising:

a preshaped and precast hollow rigid core having an opening to the environment and at least one opening to the user's eardrum;
a premolded soft, resilient, malleable covering fixed to the exterior of said rigid core having a tip which extends beyond the eardrum end of the rigid core, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal; and cover means for closing said opening to the environment;
receiver means located within said earshell assembly; and means for electrically interconnecting said receiver means to an external test device.

29. The invention as recited in claim 28 wherein said rigid core includes interlocking means located adjacent said opening to the outer ear.

30. The invention as recited in claim 28 wherein said opening to the environment in said hollow rigid core has a predetermined cross-section and wherein said cover means includes;
a test module having a cross-section corresponding to the cross-section of said opening to the environment; and interlocking means located about the periphery of said test module such that said interlocking means of said rigid core cooperate with said interlocking means of said test module to detachably interconnect said test module to said rigid core.

31. The invention as recited in claim 30 wherein said test module further comprises microphone means located within said test module and means for electrically interconnecting said microphone means with said external test device.

32. The invention as recited in claim 31 wherein said test module further includes microphone retaining means for housing said microphone means.

33. The invention as recited in claim 32 wherein said microphone retaining means include a soft, flexible cushion disposed between said test module and said microphone means.

34. A stock auditory canal hearing aid to be inserted into the right auditory canal of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing said comprising:
a prefabricated earshell assembly for said right auditory canal comprising a preshaped and precast hollow rigid body having a generally D-shaped opening to the environment adjacent the right ear oriented with the curved position of said D-shaped opening toward the back of said right ear, a tapered portion having an inward hook and an upward twist, and at least one inner opening to the right eardrum;
cover means for closing said D-shaped opening to the right outer ear;
a premolded soft, resilient, malleable covering fixed to the exterior of said rigid body having a tip which extends beyond the eardrum end of the rigid body, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal;
microphone means located within said right earshell assembly;
receiver means located within said right earshell assembly;
amplifier means located within said right earshell assembly;
means within said right earshell assembly for interconnecting said microphone means, said amplifier means and said receiver means; and means for housing a batter source located within said right earshell assembly for supplying power to said amplifier means.

35. The invention as recited in claim 34 wherein said right earshell assembly further includes:
a soft, flexible, pliant coveing of one of a selectable plurality of thicknesses and shapes having a generally D-shaped opening to the environment adjacent the right ear oriented with the curved portion of said D-shaped opening toward the back of said right ear, a tapered portion having a forward and inward hook and an upward twist, and at least one inner opening to the right eardrum, said covering being fixed to the exterior of said rigid body and resiliently conforming to the interior of said right auditory canal.

36. A stock auditory canal hearing aid to be inserted into the left auditory canal of a user which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising:
a prefabricated earshell assembly for said left auditory canal comprising a preshaped and precast hollow rigid body of singular size and shape having a generally D-shaped opening to the environment adjacent the left ear oriented with the curved position of said D-shaped opening toward the back of said left ear, a tapered portion having an inward hook and an upward twist, and at least one inner opening to the left eardrum;
cover means for closing said D-shaped opening to the left outer ear;

a premolded soft, resilient, malleable covering fixed to the exterior of said rigid body having a tip which extends beyond the eardrum end of the rigid body, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal;
microphone means located within said left earshell assembly;
receiver means located within said left earshell assembly;
amplifier means located within said left earshell assembly;
means within said left earshell assembly for interconnecting said microphone means, said amplifier means and said receiver means; and means for housing a battery source located within said left earshell assembly for supplying power to said amplifier means.

37. The invention as recited in claim 36 wherein said left earshell assembly further includes:
a soft, flexible, pliant coveing of one of a selectable plurality of thicknesses and shapes having a generally D-shaped opening to the environment adjacent the left ear oriented with the curved portion of said D-shaped opening toward the back of said left ear, a tapered portion having a forward and inward hook and an upward twist, and at least one inner opening to the left eardrum, said covering being fixed to the exterior of said rigid body and resiliently conforming to the interior of said left auditory canal.

38. A stock in-the-canal hearing aid to be inserted within the concha and meatus of a patient which is prefabricated from modular elements which are mass produced prior to fitting the patient with a hearing aid, the hearing aid comprising:
a preshaped and precast thin shelled rigid core constructed to have one end facing the environment and the other end facing the eardrum of the patient characterized by a forward and inward hook and an upward twist of that protion of the shell which extends from the concha into the meatus of the patient and a premolded soft, resilient, malleable covering fixed to the exterior of said rigid core having a tip which extends beyond the eardrum end of the rigid core, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal.

39. The hearing aid of claim 38 wherein the hearing aid is further characterized by a patient selectable one of a plurality of soft resilient covers securely affixed to the exterior of the core each of the plurality of soft covers interiorly conforming to the forward and inward hook and upward twist of the shell and the selected cover exteriorly being of a size and dimension of fit comfortably within the ear canal of the patient, the selected covering having an ovoid shape which substantially conforms to the diameter of the ear canal.

40. The hearing aid of claim 38 for use within a patient's ear canal having a plurality of bends wherein the hearing aid is characterized by having a soft malleable cover which comfortably conforms to at least one bend present in the patient's ear canal.

41. The hearing aid of claim 38 wherein the hearing aid comfortably conforms to at least two bends present in the patient's ear canal.

42. The hearing aid of claim 40 wherein the hearing aid penetrates over three-eighths of the length of the patient's ear canal.

43. The hearing aid of claim 40 wherein the hearing aid penetrates three-fourths of the length of the patient's ear canal.

44. A stock hearing aid comprising a hard shell having a first portion and a second portion, the second portion being tapered and having a forward and inward hook and an upward twist which generally conforms to the geometry of a human ear canal characterized in that said hard shell is completely enveloped with a premolded soft pliable material which accommodates the individual characteristics and geometry of each user's ear canal and having a tip which extends beyond the end of the second portion of the hard shell, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal.

45. A stock hearing aid which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid comprising a first portion which fits into the concha of the ear and a second protion which penetrates into the ear canal characterized in that the first portion of the hearing aid has a generally D-shaped cross-section with the flat side extending toward the front of the ear and the curved side extending toward the back of the ear and the second portion comprising a thin hollow shell having a soft, flexible, tip which is fixed to the exterior of said hollow shell, the tip extending beyond the eardrum end of the hollow shell, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal.

46. A mass produced hearing aid comprising an earshell assembly which fits into the ear of a patient and electronic circuit components contained within the earshell assembly which establish the frequency response of the hearing aid characterized in that the earshell assembly comprises a hollow shell having a soft, flexible tip which extends beyond the eardrum end of the earshell assembly, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal and all of the electronic circuit elements are detachably removeable from the earshell assembly.

47. A prefabricated hearing aid assembly which is prefabricated from modular elements which are mass produced prior to fitting the user with a hearing aid, the hearing aid assembly having a first cavity to contain the electronic components of the hearing aid assembly and a second cavity to vent the ear canal to the atmosphere surrounding the user of the hearing aid characterized in that the second cavity is formed by a hollow, thin shell having a soft flexible tip which extends beyond the eardrum end of the hollow shell, the tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal and the size and capacity of the second cavity which vents the ear canal to the atmosphere is controllable by selecting one of a plurality of vent inserts, each of the plurality of vent inserts having a different sized aperture formed therein.

48. A hearing aid for insertion into a patient's ear having a first portion which is retained in the bowl of the ear and a second portion which extends into the ear canal of the patient characterized in that the second portion comprises a soft flexible tip having an ovoid shape and being of sufficient length for deep penetration of the ear canal so that the tip extends past the first bend in the ear canal and penetrates the ear canal to a depth of three eighths to three quarters of the depth of the ear canal which can be selectively shortened to accommodate the physical comfort of the patient and the geometry of the patient's ear canal.

49. A mass produced hearing aid comprising a hollow earshell assembly for insertion into a patient's ear and detachable electronics attached to an amplification module for insertion into the earshell assembly characterized in that the earshell assembly has at least one ridge formed around the periphery of the inner surface thereof and the amplification module comprises a plurality of bayonet tabs having bulbous ends, each of the tabs being directed toward the ridge in the earshell assembly, both the ridge and the bayonet tabs being formed of rigid but flexible material so that when the tabs are inserted into the earshell assembly, the ridge deforms outwardly and the bulbous ends of the plurality of tabs deflect inwardly and when the bulbous ends of the tabs pass the ridge, the ridge assumes its normal position and the bayonet tabs resume their normal position so that the bulbous ends of the bayonet tabs are retained by the ridge of the earshell assembly.

50. A mass produced hearing aid comprising a hollow earshell assembly for insertion into a patient's ear and detachable electronics attached to an amplification module for insertion into the earshell assembly characterized in that the earshell assembly has at least one ridge formed around the periphery of the inner surface thereof and the amplification module comprises a plurality of bayonet tabs having bulbous ends, each of the tabs being directed toward the ridge in the earshell assembly, the ridge being formed of rigid but flexible material so that when the tabs are inserted into the earshell assembly, the ridge deforms outwardly and when the bulbous ends of the tabs pass the ridge, the ridge assumes its normal position so that the bulbous ends of the bayonet tabs are retained by the ridge of the earshell assembly.

51. A mass produced hearing aid comprising a hollow earshell assembly for insertion into a patient's ear and detachable electronics attached to an amplification module for insertion into the earshell assembly characterized in that the earshell assembly has at least one ridge formed around the periphery of the inner surface thereof and the amplification module comprises a plurality of bayonet tabs having bulbous ends, each of the tabs being directed toward the ridge in the earshell assembly, the bayonet tabs being formed of rigid but flexible material so that when the tabs are inserted into the earshell assembly, the bulbous ends of the plurality of tabs deflect inwardly and and when the bulbous ends of the tabs pass the ridge, the bayonet tabs assume their normal position so that the bulbous ends of the bayonet tabs are retained by the ridge of the earshell assembly.