Reconstruction of the Audiogram Using Brain Stem Responses and High-Pass Noise Masking

Abstract

Contributions to the brain stem electrical responses (BSER) presumably initiated from specific frequency regions of the cochlea with center frequencies similar to the major audiometric frequencies (0.5, 1, 2, 4, and 8 kHz) are derived by the application of a high-pass noise masking technique utilizing click stimuli. In normal hearing subjects, these derived narrow-band responses from the midfrequency regions (4, 2, and 1 kHz) can be recognized at click levels as low as 10 dB HL. For the frequency regions around 8 kHz and 0.5 kHz, these derived responses can be discerned at click levels of 30 dB HL and higher. When one uses the lowest click level at which these derived responses can be obtained from a given frequency region, the differences between a patient with a hearing loss and a normal hearing subject correlate well with the amount of hearing loss (air conduction) recorded by conventional pure tone audiometry. Use of the high-pass noise masking technique to reconstruct the audiogram may be of great potential value in assessing young children and other individuals who cannot or will not respond to conventional audiometry.