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Acoustical characteristics of surgically altered human temporal bones
Clinical Otolaryngology and Allied Sciences
|April 1, 1984
Summary
Modified radical mastoidectomy surgery alters the ear canal's sound pressure levels, potentially impacting speech discrimination. Further studies are needed to compare surgical effects with disease impact on hearing.
Area of Science:
- Otolaryngology
- Acoustics
- Audiology
Background:
- The external auditory canal amplifies sound pressure levels (SPL) between 2-4 kHz.
- This resonance is crucial for hearing, especially speech discrimination.
- Surgery on the ear canal may alter these acoustic properties.
Purpose of the Study:
- To investigate the acoustic changes in the tympanic membrane's sound pressure level after modified radical mastoidectomy.
- To assess the potential impact of these acoustic changes on speech discrimination in noise.
Main Methods:
- Modified radical mastoidectomy was performed on 6 human temporal bones.
- Sound pressure level (SPL) transfer functions were measured at the tympanic membrane.
- The measured acoustic alterations were applied to 2 subjects to evaluate speech discrimination in noise.
Main Results:
- Surgery resulted in significant SPL alterations across frequencies: +10 dB at 2 kHz, +14 dB at 2.5 kHz, -20 dB at 4 kHz, and -16 dB at 5 kHz.
- Speech discrimination in noise decreased by 6% when the surgical transfer function was applied.
- The study quantifies the acoustic impact of modified radical mastoidectomy on the ear canal's resonance.
Conclusions:
- Modified radical mastoidectomy alters the sound pressure level transfer function of the external auditory canal.
- A measurable reduction in speech discrimination in noise was observed.
- Prospective studies are required to compare the surgical impact with the effects of the underlying disease.