Patent ID: 8558708
Filing Date: 2013-10-15
Classification: G08B

Abstract:
1. A supplemental alert generation device for monitoring, and supplementing an audible alert generated by, a detector/alert device, the supplemental alert generation device comprising: a piezoelectric sensor that passively converts sound into an electric signal; a threshold detector connected to the piezoelectric sensor and operative to monitor the electrical signal, said threshold detector operative to generate a notification signal when the electrical signal exceeds a threshold level corresponding to a threshold sound level; a controller programmed to respond to the notification signal by at least initiating a signal analysis process to assess whether an audio signal generated by the piezoelectric sensor represents an audible alert signal, said controller additionally programmed to initiate generation of a supplemental alert signal when the audible alert signal is detected, said supplemental alert signal having a fundamental frequency and a plurality of higher frequency harmonics, wherein the fundamental frequency is lower than a tone frequency of the audible alert signal and falls within a range of 400 to 700 hertz; a speaker enclosure assembly that outputs the supplemental alert signal, said speaker enclosure assembly comprising an audio speaker mounted to a speaker enclosure structure, said speaker enclosure assembly having an object resonance in the range of 400 to 700 hertz, said speaker enclosure configured to produce a low frequency audible output boost at least partly by causing energy in at least one of the harmonics to be shifted downward in frequency, wherein the speaker enclosure assembly is sealed, such that the low frequency audible output boost is achieved without reliance on a Helmholtz effect; and a battery-powered amplifier that drives the audio speaker.