Inner hair cell responses to the 2f1-f2 intermodulation distortion product.
Recordings of dc and ac receptor potentials from pigmented guinea pig inner hair cells indicate strong responses to the 2f1-f2 intermodulation tone when f1 and f2 are greater than the hair cell characteristic frequency and do not cause a response when given individually. The effective magnitude of this cubic distortion product (CDP) was about 25-30 dB below equal sound level primaries over a 20-30-dB range of their sound levels. The relative strength of the CDP declined at a rate greater than 180-dB/oct separation of the primaries. When magnitude of f1 or f2 was held constant, the growth of CDP was nonmonotonic, exhibiting a distinct maximum. With a constant level of f1 or f2, optimal CDP was produced when the level of f2 was 10-15 dB greater than f1. Strong two-tone suppression from the primaries has a role in shaping the CDP growth. The ac receptor potentials of the CDP show a 150 degrees-200 degrees phase shift when the primaries are increased over a 50-dB range. These results support the hypothesis of a propagated CDP in the cochlea and are consistent with the major features of related studies of human psychoacoustic experiments, afferent nerve neural rate functions, and ear canal distortion products.
Nuttall
A L
AL
University of Michigan, Kresge Hearing Research Institute, Ann Arbor 48109-0506.
Dolan
D F
DF
D000161:Acoustic Stimulation; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000502:physiology*; D006199:Hair Cells, Auditory, Inner / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D010470:Perceptual Masking / Q000502:physiology*