Sound Pressure Generated in an External-Ear Replica by a Nearby Point Source

Abstract

A physical replica of the external ear has been mounted in a large rigid plane. A point source of sound is placed a few centimeters from the earcanal entrance and at any desired angular position. The sound pressure at selected positions in the external ear is measured with a probe-tube microphone over the frequency range 1–15 kcps. The ratio of earcanal pressure to reference pressure measured at a reflecting plane surface is substantially independent of source distance for d⩾8 cm. Response curves at the eardrum are markedly dependent on angle of incidence above 4 kcps. A well-defined resonance at 2.8 kcps is measured at all positions in canal and concha. The concha alone has a very broad quasilongitudinal (depth) resonance at 4–6 kcps and transverse resonances above 9 kcps.