This device has a detection means to measure the relative amount of air movement in its vicinity. The detection means is coupled to a processing means for creating a variable trigger signal that is proportional to detected air movement. The detection means consists of a differential pressure transducer mounted inside a specially-shaped enclosure. The pressure transducer is arranged to measure the air pressure difference between two holes in the enclosure. The shape of the enclosure causes air to flow at different velocities near the holes, creating a differential air pressure. The processing means consists of a microprocessor that periodically samples the signal from the differential pressure transducer. A programmed algorithm calculates a variable trigger signal value based on a plurality of sampled signals. The processing means can also incorporate an algorithm for digitally generating audio signals that have attributes based on the value of the trigger signal.