Response to “Comment on ’Two-tone suppression of inner hair cell and basilar membrane responses in the guinea pig’” [J. Acoust. Soc. Am. 94, 3509–3510 (1993)1

This letter provides additional data concerning the nature of two-tone suppression when an above characteristic frequency (CF) tone suppresses the responses of hair cells (in the basal turn of the cochlea) stimulated by lower than characteristic frequency tones. It is shown that the phase of the ac receptor potential of the below CF probe tone undergoes a phase lag during suppression. This is the opposite direction from that which would occur during attenuation of the probe. These data are consistent with the changes that have been reported [Cheatham and Dallos, J. Acoust. Soc. Am. 94, 3509–3510 (1993)] in turns two and three of the guinea pig cochlea. Other additional data are provided showing that the phase change of a probe tone having a frequency higher than CF is a function of whether the high-side supressor is excitatory or nonexcitatory for the hair cell. Nonexcitatory high-side suppression is attenuation-like, whereas the mutual suppression of two (close in frequency) excitatory tones are not like attenuation.