Auditory brainstem response in the cat. Effect of masking level on derived-band contributions

The auditory brainstem responses evoked by 1 and 4 kHz tone-bursts and clicks at stimulus levels 40 dB above response threshold have been recorded in the anaesthetized cat, and octave-wide derived bands were obtained by the differential high-pass masking procedure. Masking level was varied systematically. Raising masking level to maximally 10 dB of over-masking results in a basalward shift of derived-band contributions, the amplitude of both waves I and IV increasing in the highest frequency band and falling in the most apical. Higher masking levels produce an increase in wave latency in the individual bands, which is greatest at the lowest frequencies. Comparable levels of under-masking have opposite but lesser effects.