A 1/3 octave-band noise generator for sound-field audiometric measurements

The design of a low-cost 1/3 octave-band noise generator is presented. This device produces 1/3 octave bands of noise with center frequencies from 100 to 10,000 Hz using a recently introduced switch-capacitor filter with a frequency response which is similar to that of the 1/3 octave filters in the GR 1925 multifilter. The spectrum level of the noise bands produced by this device falls at a rate of 60 dB/octave or more. The noise generator may be used with an audiometer for sound-field measurements in non-anechoic audiometric testing rooms or for earphone measurements. It may also be used as a 1/3 octave-band filter with a center frequency from 100 to 10,000 Hz or as an octave-band filter with a center frequency from 125 to 8000 Hz.