Auditory temporal and spectral resolution in normal and impaired hearing.

Temporal, spectral, and combined temporal-spectral resolution of hearing was assessed by recording masked hearing thresholds. The masker was an octave band noise. Spectral resolution was assessed by introducing a spectral gap of half an octave bandwidth in the masker. A 50-msec gap assessed temporal resolution. The spectral and temporal gaps were used separately or simultaneously. Normal-hearing and hearing-impaired subjects participated. For each masking condition, the subjects were tested at masker levels 50, 60, 70, and 80 dB SPL and at test-tone frequencies 0.5, 1, 2, and 4 kHz. Normal-hearing subjects showed reduced masking with spectral and temporal gaps. The combination of spectral and temporal gap reduced masking further. The release of masking was dependent upon the masker level. Hearing-impaired subjects showed less release of masking than normal-hearing subjects. The degree of hearing impairment was inversely related to release of masking. Reliability of the test procedure was assessed.