Psychophysical tuning curves in normal and impaired ears

Abstract

Frequency selectivity in ears suffering sensorineural hearing deficits was assessed using a tone-on-tone masking paradigm. Psychophysical tuning curves relating level of a continuous tonal masker required to just mask a probe of constant frequency and intensity to the frequency of the masker were obtained for several normal and impaired ears. In agreement with the recent observation of Vogten (in Facts and Models in Hearing, E. Zwicker and E. Terhardt, Eds.), for high-level probes (≃70 dB SPL) psychophysical tuning curves displayed well-defined minima (corresponding to maximum masking) at masker frequencies below the frequency of the probe. This “negative-maximum-masking frequency” effect was observed at sensation levels of 20 dB or less in both normal ears exposed to wide-band background noise and in ears impaired by acoustic trauma. In one patient having a uniform hearing loss of 60 dB at low frequencies, tuning curves did not contain either negative-maximum-masking frequencies or well-defined minima. Interpretations of the data in terms of the interaction between the masking effects of the tonal background and the effects of sensorineural impairment are discussed.