An Artificial Voice and Miniature Anechoic Chamber for Hearing Aid Measurements

There is described an enclosure for a standard loudspeaker mechanism which provides a compact sound source or artificial voice. With a size slightly larger than a human head, the frequency range is 100 to 7000 cps. A simple and reproducible arrangement of damping felt gives unusual flatness. This artificial voice can either be used in free space or with a small chamber arranged as an acoustic labyrinth, for testing microphones and hearing aids. In the chamber, a calibrating microphone is mounted opposite the test microphone for continuous monitoring. Simple RC compensating networks are utilized to equalize the sound source for either free‐space or labyrinth measurements.