The human auditory brainstem response to high click rates: aging effects.

Area of Science:

• Neuroscience
• Audiology
• Gerontology

Background:

• Previous research indicated age-related differences in auditory brainstem response (ABR) wave V latency.
• Limitations in prior studies prevented evaluation of wave I latency due to recording challenges.

Purpose of the Study:

• To optimize the recording of ABR wave I.
• To investigate age-related differences in ABR waves I and V latencies and amplitudes across varying click rates.

Main Methods:

• Utilized a high-level click stimulus (115 dB pSPL) and a tympanic membrane inverting electrode for improved wave I recording.
• Recorded ABRs using conventional methods (11-75 Hz) and maximum length sequences (MLS) (100-500 Hz).
• Compared ABR parameters between young adults and older adults with normal or near-normal hearing thresholds.

Main Results:

• Both age groups exhibited similar increases in peak latencies and I-V interval with increasing click rate.
• Peak amplitudes decreased with increasing click rate in both young and older adults.
• A notable finding was the substantially smaller wave I amplitude in older subjects compared to younger subjects.

Conclusions:

• Age-related changes in ABR characteristics with increasing click rate are largely similar between young and older adults when hearing thresholds are normal or near-normal.
• The reduced wave I amplitude in older adults suggests potential subtle age-related changes in the auditory nerve or cochlear microphonics.
• Optimized recording techniques allowed for robust evaluation of both wave I and V, facilitating more comprehensive ABR analysis across age groups.