Frequency summation observed in the human acoustic reflex

Tetsuaki Kawase, Hiroshi Hidaka, Tomonori Takasaka

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


It is known that the threshold of an acoustically induced middle-ear-muscle (MEM) reflex can be lowered by the simultaneous presentation of a second tone (facilitator), which is presented to the ipsilateral or contralateral ear at a level below the acoustic reflex threshold (ART) of the facilitator itself (Sesterhenn and Breuninger, 1976; Blood and Greenberg, 1981). In the present study, a primary elicitor and a facilitator were presented to the ear contralateral to that used for measurement of the acoustic reflex (AR), and the effects of changing frequencies and sound levels of the facilitator were investigated in human subjects with normal ears. The sound levels of facilitators, which caused a significant reduction of ART for the primary elicitors (facilitation thresholds), showed an asymmetrical pattern as a function of frequency of the facilitators. The facilitation thresholds tended to be lower when a facilitator with a frequency lower than the frequency of the elicitor (1 kHz) was used. In addition, effects of the elicitor on the masked thresholds of the facilitator were examined to observe the possible interaction between elicitor and facilitator from the viewpoint of 'spread of excitation.' The underlying mechanism of summation effects of two tones are discussed based on the possible input mechanism involved in the acoustically induced MEM reflex are.

Original languageEnglish
Pages (from-to)37-45
Number of pages9
JournalHearing Research
Issue number1-2
Publication statusPublished - 1997 Jun


  • Acoustic reflex
  • Human
  • Middle ear muscle
  • Summation

ASJC Scopus subject areas

  • Sensory Systems


Dive into the research topics of 'Frequency summation observed in the human acoustic reflex'. Together they form a unique fingerprint.

Cite this