Life safety device with folded resonant cavity for low frequency alarm tones

A life safety device with a compact audio output apparatus to emit a low frequency alarm tone comprising:

• electronic control circuitry;
• an environmental condition sensor;
• an audio output transducer;
• the compact audio output apparatus comprises a folded, resonant cavity coupled to the audio output transducer;
• the folded, resonant cavity is axisymmetric about a central longitudinal axis;
• the folded, resonant cavity comprises an undulating, acoustic path whereby the acoustic path turns at least once by approximately 180 degrees;
• the folded resonant cavity amplifies the sound emitted from the audio output transducer;
• and
• the audio output apparatus emits a low frequency tone as signaled by the electronic control circuitry when the environmental condition sensor senses an environmental condition.

An environmental condition detector emitting a low frequency alarm tone comprising:

• electronic control circuitry;
• an environmental condition sensor;
• an audio output transducer;
• a multi-folded, axisymmetric, acoustic resonant cavity comprising one particle displacement node region and one particle displacement antinode region with an undulating acoustic passage connecting the node region with the antinode region;
• the multi-folded, resonant cavity is coupled to the audio output transducer;
• the multi-folded, resonant cavity amplifies acoustic waves emitted from the audio output transducer when the audio output transducer emits a low frequency tone as signaled by the electronic control circuitry when the sensor senses an environmental condition;
• and
• the multi-folded, resonant cavity fits within a housing also enclosing the electronic control circuitry, the sensor, and the audio output transducer.