Recordings of dc and ac receptor potentials from pigmented guinea pig inner hair cells indicate strong responses to the 2f1f2 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°–200° 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.

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