Acoustic reflexes in the measurement of auditory filters at high levels in normal listeners.

The possible influence of the acoustic reflex in auditory filter shape measurements was investigated in 4 normal listeners by measuring contralateral acoustic reflexes to stimuli used in the notched-noise method. For probe/masker combinations centred at 125 and 250 Hz, the reflex was, at most, barely detectable even at masker levels of 80 dB SPL/Hz. On the other hand, all listeners had a measurable reflex at a masker level of 70 dB SPL/Hz for a probe/masker combination centred at 1 kHz. Some listeners also evidenced reflexes at a masker level of 60 kB SPL/Hz at this frequency and at 70 dB SPL/Hz at 500 Hz. As it is known that the acoustic reflex significantly attenuates frequency components of sounds below about 2 kHz as they pass through the middle ear, it appears that estimates of auditory filter bandwidths at high levels at 0.5 and 1 kHz can be influenced to some degree by the reflex.