Human ears were utilized to examine the effects of change in earmold form upon sound‐pressure levels in the ear canal at selected discrete frequencies from 0.1 to 4 kHz. Four earmolds were fabricated for each of eight subjects. One retained an unaltered form for the purpose of comparison, while the other three were modified, respectively, to a shortened canal form, a shortened canal form which was vented, and an open form. Measurements were made utilizing a probe‐tube microphone assembly. Relative to the unaltered earmold form, the shortened canal modification caused a slight reduction for all frequencies except 3 and 4 kHz, while the vented and open forms produced marked reductions in low‐frequency response accompanied by large resonances. Certain relevant measurements made using a standard 2‐cm3 a coupler and a special 2‐cm3 coupler are also presented.

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