Patent ID: 9179220
Filing Date: 2015-11-03
Classification: G08B,G10K,H04R

Abstract:
1. A life safety device with an audio output apparatus to emit a low frequency alarm tone comprising: electronic control circuitry; an environmental condition sensor; a housing; an audio output transducer; the electronic control circuitry sends an electronic audio signal to the audio output transducer when the environmental condition sensor senses an environmental condition; the audio output apparatus comprises the audio output transducer acoustically coupled to a folded, resonant cavity filled with a substantially fixed and contained mass of air; the folded, resonant cavity comprises an undulating, acoustic path created by at least one resonant cavity fold; the fundamental resonant frequency of the audio output transducer and the fundamental resonant frequency of the folded, resonant cavity substantially match; the resonant cavity amplifies an audible, low frequency tone emitted into ambient surroundings; and the housing encloses the electronic control circuitry, the environmental condition sensor, and the audio output apparatus.