Variable venting valve for earmolds.

Abstract

The frequency response and loudness reduction characteristics of earmolds with variable venting valves (VVV) were investigated. Both side-branch and laterally vented earmolds were employed. Sound pressures were measured at 44 frequencies from 100 to 4 000 HZ in a modified HA-2 coupler with the VVV in four stages of opening: closed; 1/3 open; 2/3 open and 3/3 open. The effect of venting is primarily in the low frequencies. Little or no reduction in intensity is observed in the 'speech frequency' range and a modest amount is noted in the higher frequencies. The side-branch vented earmolds were more effective than the laterally vented earmolds. Calculated loudness reductions in phons were small. The effectiveness of the VVV, whether assessed by the frequency response or loudness reduction characteristics, is achieved within the first 1/3 of opening: further opening has little effect. The utility of the VVV, especially to the geriatric hearing aid user, is questionable.