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The Effects of Middle-ear Stiffness on the Auditory Brainstem Neural Encoding of Phase
Jordan M Racca1,2, Rafael E Delgado3, René H Gifford4
1Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA. jordan.racca@vanderbilt.edu.
Journal of the Association for Research in Otolaryngology : JARO
|October 10, 2022
Summary
Increased middle-ear stiffness alters auditory brainstem neural encoding of sound phase. This finding impacts understanding spatial hearing in individuals with middle-ear stiffness changes, like otosclerosis patients.
Area of Science:
- Auditory Neuroscience
- Acoustic Physiology
Background:
- The middle ear's mass-stiffness balance is crucial for sound transmission.
- Auditory phase encoding is vital for binaural hearing and spatial sound localization.
Purpose of the Study:
- To examine how middle-ear stiffness affects auditory brainstem neural phase encoding in adults.
- To explore the link between middle-ear stiffness, acoustic immittance, and neural phase encoding.
Main Methods:
- Auditory steady-state response (ASSR) measured neural phase encoding.
- Middle-ear stiffness manipulated via contralateral middle-ear muscle reflex (MEMR) activation.
- Wideband acoustic immittance assessed acoustic absorbance to quantify stiffness.
Main Results:
- Contralateral MEMR activation increased middle-ear stiffness, indicated by decreased acoustic absorbance.
- Increased stiffness led to reduced ASSR phase lag, altering neural phase encoding.
- No significant correlation found between stiffness-induced absorbance changes and ASSR phase.
Conclusions:
- Middle-ear stiffness significantly influences auditory brainstem neural encoding of phase.
- Findings are relevant for audiologic and otologic populations with altered middle-ear mechanics.
- Implications for understanding binaural hearing in conditions like otosclerosis and cochlear implant users.
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