Psychophysical tuning curves and recognition of highpassand lowpass filtered speech for a person with an invertedV-shaped audiogram (L)

摘要

A single subject whose audiogram resembled an inverted V shape (good hearing at 4000 Hz, andpoorer hearing at other frequencies) was tested. Results of the threshold-equalizing noise testsuggested that a dead region (DR) in the cochlea was present at all test frequencies from 500 to 3000Hz, but no DR was present at 4000 Hz. Psychophysical tuning curves (PTCs) obtained using signalfrequencies of 2000, 3000, 4000, and 6000 Hz showed upward shifted tips for the lowest two signalfrequencies, and a downward shifted tip for the highest frequency. The results of the PTCs suggesteda functioning region extending from 3900 to 5100 Hz, with DRs outside that range. Theidentification of nonsense syllables, amplified according to the "Cambridge formula," was measuredas a function of lowpass or highpass filter cutoff frequency. The results suggested that useful speechinformation could only be extracted from a limited frequency range around 4000 Hz.