Time-intensity relations in Békésy audiometry

Area of Science:

• Audiology
• Neuroscience
• Hearing Science

Background:

• Bekesy audiometry is a standard method for assessing hearing thresholds.
• Auditory adaptation, the decrease in response over time, is crucial for understanding hearing function.
• Abnormal adaptation is implicated in various hearing impairments.

Purpose of the Study:

• To investigate the effects of modified Bekesy audiometry on auditory adaptation in different hearing loss groups.
• To explore the relationship between adaptation abnormalities and Bekesy tracing characteristics.
• To differentiate responses in normal hearing, sensorineural hearing loss, and functional hearing loss.

Main Methods:

• Utilized fixed frequency Bekesy pure tone audiometry.
• Introduced +/- 20 dB intensity changes at the threshold of audibility and inaudibility.
• Measured spike amplitude changes and time constants in response to these modifications.
• Included subjects with normal hearing, sensorineural hearing impairment, and functional hearing loss.

Main Results:

• Normal hearing subjects showed a consistent reduction in spike amplitude (approx. 4 dB) with +/- 20 dB changes.
• Subjects with sensorineural hearing loss exhibited reduced amplitude reduction for continuous tones (3 dB) compared to pulsed tones (4 dB), suggesting abnormal adaptation.
• A case of multiple sclerosis with excessive adaptation showed increased amplitude for continuous tones under specific +/- dB conditions.
• Functional hearing loss subjects displayed variable responses, emphasizing time or intensity.

Conclusions:

• Modified Bekesy audiometry effectively highlights differences in auditory adaptation across hearing conditions.
• Abnormal rapid adaptation may explain reduced spike amplitudes in sensorineural hearing loss.
• Slow adaptation mechanisms might be involved in specific cases of excessive adaptation.
• Functional hearing loss responses are inconsistent and may reflect complex processing or response strategies.