Inaudible stimulus may cause threshold shift

Interrupted pure‐tone threshold measurements were made monaurally by Bekesy audiometry with and without presentation of inaudible identical continuous stimulus and white noise on subjects with bilateral normal hearing and unilateral sensorineural hearing loss with and without abnormal auditory threshold adaptation. Thresholds were compared for interrupted stimulus only and both interrupted stimulus and inaudible stimulus presentation. Subjects with normal hearing and sensorineural hearing loss without abnormal adaptation showed no difference with and without presentation of the inaudible continuous stimulus. Subjects with sensorineural hearing loss demonstrating marked abnormal adaptation revealed observable threshold shift for the interrupted stimulus by adding inaudible stimulus. It is assumed that the inaudible stimulus affecting partially damaged nerve fibers produce widespread abnormal adaptation that the threshold for another signal is inaudible until an abnormally high intensity is reached. A stimu...