Brain stem response audiometry at speech frequencies

Abstract

Auditory-evoked brain stem response (BSR; wave V) was studied, using tone pips at three speech frequencies (500, 1 000 and 2 000 Hz) as stimuli. The tone pips consisted of 5-ms rise-decay times without a plateau. BSR recordings were made in 10 normal subjects and in 16 subjects with impaired hearing. In the normal subjects, BSR thresholds ranged from 10 to 20 dB SL at these three frequencies. In the subjects with impaired hearing, BSR thresholds corresponded well to conventional pure-tone thresholds at each frequency in cases of low- as well as high-frequency hearing loss. In all subjects with impaired hearing, the BSR thresholds were higher by as much as 25 dB than the pure-tone thresholds. The mean differences between these two thresholds at 500, 1 000 and 2 000 Hz were 11.3 ± 8.0, 10.9 ± 6.2 and 10.9 ± 7.3 dB, respectively.

Thus, we conclude that the BSR is useful for objective assessment of hearing thresholds at each of these speech frequencies.

Key Words:

• Brain stem response
• Tone pip
• Speech frequency
• Objective audiometry