An audible alarm is provided for use in an alarm system which produces a plurality of distinct audible alarm signals in response to a control signal. The audible alarm can further produce a prerecorded voice message which can be stored at the audible alarm. A microcontroller at the audible alarm controls...http://www.google.fr/patents/US20020135491?utm_source=gb-gplus-shareBrevet US20020135491 - Electronically controlled multi-tone peripheral
