Earcanal Pressure Generated by a Free Sound Field

The pressure levels generated at the entrance to the earcanal by progressive waves from a point source at a distance of 1 m have been measured for a group of ten subjects. Individual curves are presented for all ten subjects at six azimuthal angles of incidence. Measurements at 0°, 45°, 90°, and 180° cover the frequency range 0.2–14 kcps. Measurements at 270° and 315° extend to 8 kcps. The average earcanal-versus-free-field pressure levels are in good agreement with Wiener's data over the common frequency range. Certain features (maxima at 2.4 and 13 kcps, minima at 4 and 10 kcps) appear to be relatively independent of angle of incidence. Others (peak at 7 kcps) have strong azimuthal dependence. Normal modes of the concha may have an important role in the 6- to 10-kcps region.