Patent ID: 8810426

Claim:
A life safety device comprising: electronic control circuitry; a sensor connected to the electronic circuitry; an audio output apparatus comprising an audio output transducer acoustically coupled to a compact circumferential acoustic resonator; the electronic circuitry drives the audio output apparatus to emit a tone when the sensor senses an environmental condition; the compact circumferential acoustic resonator comprises a transducer coupling port and a ring-shaped cavity, having a proximal end and a distal end, wherein axial acoustic waves emitted from the audio output transducer traverse a transducer coupling port and are directed through the radial port into the ring-shaped cavity where the axial acoustic waves are transformed into tangential acoustic waves; the tangential acoustic waves reflect off a node forming wall at the distal end of the ring shaped cavity, the node forming wall oriented perpendicular to direction of motion of the tangential acoustic waves; and the sensor comprises one of a smoke sensor, a carbon monoxide sensor, a natural gas sensor, an intrusion sensor, a glass break sensor, a temperature sensor, or a vibration sensor.