Masking of Tones by Noise for the Cat

Masked thresholds were obtained by the method of behavioral audiometry fur each of four cats at eleven frequencies over the range from 125 to 16 000 cps. Bands of noise, which were approximately one to two octaves wide, as well as two broad bands of noise, were used as masking stimuli. Experiment I shows that the function relating masking to noise level has exactly the same form for cat as for man; the signal to-noise ratios, however, are greater for cat than for man. The critical ratio (K) is defined as the ratio of signal power to spectrum level at the masked threshold. The function relating K to frequency was determined for cat in experiment II; tiffs function parallels that for man, but lies 4 to 5 dB above it at most frequencies. The masking data for the cat are shown to be consistent with measurements of frequency discrimination for this animal.