Diffuse field response of the ear

The ear canal pressure developed in a diffuse‐field facility complying with ANSI S12.6‐1984 was measured on 20 adult subjects (11 male and 9 female), with two replications on each ear for 19 of the 20 subjects. A soft 1‐mm‐o.d. silicone rubber probe tube was inserted until the subject reported the “thump” of the tube bumping the eardrum, and then withdrawn a couple of mm. Preliminary experiments indicated that this technique did not always produce the same results, with some curves on the same ear of the same subject showing substantially less “eardrum SPL” in the 8‐ to 20‐kHz region than others. It was sometimes (but not always) possible to confirm with otoscopic examination that the lower‐SPL curves corresponded to probe‐tube locations away from the eardrum. Based on the preliminary experiments, data from the “best run of the best ear” (i.e., highest level above 8 kHz) were averaged. The resulting curve was similar to the curve obtained on a KEMAR manikin in the same sound field.