pistonphone

The pistonphone is a laboratory device used to generate controlled acoustic pressures in air by moving a piston within a sealed cylinder. It serves as a simple acoustic source and, in some applications, as a calibration instrument for measuring sound pressure levels.

It consists of a precision cylinder with a close-fitting piston, driven by a motor or actuator to produce sinusoidal changes in air volume. The resulting pressure waveform depends on piston area, stroke, and system compliance, while friction and seal quality affect distortion. Output is controlled by drive amplitude and frequency.

In practice, pistonphones have been used in acoustics laboratories to generate reference signals for microphone calibration, to study piston-driven sound generation, and as educational demonstrations of basic acoustics.

Historically, the term "pistonphone" is largely historical and infrequently used in modern acoustics. Early references describe it as a simple piston-based source; contemporary devices typically use dedicated calibrated loudspeakers or standardized piston sources with more sophisticated control.

Related topics include loudspeakers, microphones, and acoustic calibrators.