PISTONPHONE

A pistonphone is an accurate and stable reference source for calibrating a sound level meter before use. The device is normally battery powered and comprises a small electric motor which drives a piston situated at one end of a small (a few millilitres) cavity into which the microphone of the sound level meter is introduced. The known and accurate excursion of the piston allows a high and constant sound pressure level to be achieved. A similar device, known as a sound level calibrator, is used for the same purpose but comprises an audio oscillator (1 kHz) and a small loudspeaker rather than a motor and piston. In addition to calibrating sound level meters they are also required for the calibration of a hearing aid test box and they are commonly found in audiology or medical physics departments.

Content and Design Copyright 2000 Dr. Malcolm C Brown.  See Title Page for more details