A life safety system for monitoring a building has a plurality of detectors for detecting alarm conditions located throughout the building, a plurality of speakers located throughout the building, a source of pre-stored voice messages which can be broadcast over the speakers, and a telephone network....http://www.google.es/patents/US4682348?utm_source=gb-gplus-sharePatente US4682348 - Life safety audio system having a voice synthesizer and a constant volume telephone network
Life safety audio system having a voice synthesizer and a constant volume ...
