Psychophysical frequency resolution in the cat as determined by simultaneous masking and its relation to auditory-nerve resolution

Abstract

Critical bandwidths were measured behaviorally at 1 and 2 kHz by simultaneous masking in 4 cats. Three methods were used; the masking of a tone by noise of variable bandwidth; the masking of a narrow-band signal by 2 tones; and the masking of a tone by noise of rippled spectrum. The 3 methods agreed closely and gave a mean critical bandwidth of 410 Hz at 1 kHz and 690 Hz at 2 kHz. These values were about 3 times as great as the electrophysiologically-determined effective bandwidths of single fibers of the auditory nerve at the same frequencies, both as measured in other animals, and in 1 of the animals that was tested behaviorally as well. Psychophysical tuning curves were also determined behaviorally; they agreed closely with auditory-nerve fibers in both bandwidth and slope. Apparently the critical band as measured by simultaneous masking is not a close relation of the frequency-threshold curve of auditory-nerve fibers, but that the psychophysical tuning curve possibly may be.