An anechoic chamber and point source design for audiological measurement Free

A point source in a 6‐ft cubed anechoic space was designed to provide predictable audio sound fields at 1 m without near‐field effects. The chamber was acoustically isolated to permit measurement down to 25 dB SPL in an $812 × 9 × 11foot o.d.$ enclosure. A control microphone 20 cm from the source maintained a constant SPL at 1 m over the entire frequency range. The presence of a full size human manikin did not affect the sound field at the control microphone. SPL followed inverse square law (± 1 dB) from 10 cm to 1 m from the source over a 200 Hz to l0 kHz frequency range. Eight loudspeakers, mounted behind the upper edge wedges could develop 70 dB SPL quasi‐diffuse noise at the working location.