Effects of excitatory and non-excitatory suppressor tones on two-tone rate suppression in auditory nerve fibers

John A. Costalupes*, Nola C. Rich, Mario A. Ruggero

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Recordings were obtained from individual auditory nerve fibers in anesthetized chinchillas. Rate versus level functions were obtained for best frequency (BF) tones alone and for simultaneously-gated tone pairs comprising a BF tone and a second tone at a fixed intensity that produced evidence of two-tone rate suppression. Care was taken in selecting a range of suppressor tone levels that included excitatory (i.e., the suppressor tone evoked a rate change by itself) and non-excitatory (i.e., no suppressor tone-evoked rate increase) suppressor tone levels. Addition of a suppressor tone produced a shift of the dynamic range portion of the BF rate versus level function to higher test intensities. A parallel shift of the dynamic range portion of the rate versus level function was associated with a non-excitatory suppressor tone. The shift produced by an excitatory suppressor tone was characterized by a decrease in slope. Results indicated that the magnitude of shift increased monotonically as suppressor tone intensity was raised and that there was a gradual transition from a non-excitatory response to an excitatory response. The rate of shift (i.e., dB of shift per dB change in suppressor tone intensity) did not differ for non-excitatory versus excitatory responses, but was substantially greater for below-BF suppressor tones (1.38 dB/dB) than for above-BF suppressor tones (0.54 dB/dB). The rate of shift did not, however, appear to be related systematically to suppressor tone frequency separation from BF. Above- and below-BF suppression was noted for fibers over the range of best frequencies tested (110 Hz to 16.4 kHz).

Original languageEnglish (US)
Pages (from-to)155-164
Number of pages10
JournalHearing research
Issue number2
StatePublished - 1987


  • Auditory nerve fiber
  • Chinchilla, Tone, Average rate
  • Suppression

ASJC Scopus subject areas

  • Sensory Systems


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