The amount of acoustic radiation produced by two samples of a Radioear 8–71, 8–72, and Pracitronic KH 70 bone vibrator was determined for 30 normal-hearing subjects at 4000 Hz. The mean amount of acoustic radiation was very similar for both samples of each vibrator type but significantly (p c 0.05) different between the bone vibrator types. The mean amount of acoustic radiation averaged over both samples was 8.3 dB for the 8–72, 4.3 dB for the 8–71, and −0.3 dB for the KH 70. Individual subject data indicated that the 8–72 produced excessive acoustic radiation (>5 dB) for 80% of the subjects, the 8–71 for 38% of the subjects, and the KH 70 for 8% of the subjects which could cause an invalid high-frequency air-bone gap. Precautions should be taken during bone conduction audiometry to eliminate the possibility of acoustic radiation produced by bone vibrators. A need for additional standards in this area is stressed.
Address reprint requests to Tom Frank, Ph.D., Speech and Hearing Clinic, 5-8 Moore Building, The Pennsylvania State University, University park, PA 16802.
Received August 7, 1985; accepted April 11, 1986.
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