Miranda FA, Aguilar-Vidal E. Magnitude of the contralateral efferent olivocochlear effect as a function of the frequency.
J Otol 2022;
17:67-71. [PMID:
35949552 PMCID:
PMC9349011 DOI:
10.1016/j.joto.2021.11.004]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/07/2021] [Accepted: 11/30/2021] [Indexed: 11/28/2022] Open
Abstract
Background
The activation of the medial olivocochlear reflex reduces the cochlear gain, which is manifested perceptually as decreased auditory sensitivity. However, it has remained unclear whether the extent of this suppression varies according to the cochlear region involved. Here we aims to assess the magnitude of contralateral efferent suppression across human cochlea, at low levels, and its impact on hearing sensitivity.
Methods
Assuming that acoustic stimulation activates the contralateral medial olivocochlear reflex, we evaluated the magnitude of the suppressive effect as a function of frequency in 17 subjects with normal hearing. Absolute thresholds were measured for bursts tones of various durations (10, 100, and 500 ms) and frequencies (250, 500, 1000, 4000, and 8000 Hz) in the presence or absence of contralateral white noise at 60 dB SPL.
Results
We found that contralateral noise raised the absolute threshold for the burst tones evaluated. The effect was greater at lower than higher frequencies (3.85 dB at 250 Hz vs. 2.22 dB at 8000 Hz).
Conclusions
Our findings suggest that in humans, the magnitude of this suppression varies according to the cochlear region stimulated, with a greater effect towards the apex (lower frequencies) than the base (higher frequencies) of the cochlea.
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