Audiologic characterization using clinical physiological measures: Normative data from macaque monkeys.

Area of Science:

• Auditory Neuroscience
• Comparative Physiology
• Otoacoustic Emissions

Background:

• Clinical auditory measures like ABRs and DPOAEs lack specificity for subtle cochlear damage.
• Animal models offer controlled environments to study subclinical cochlear pathologies.
• Macaque monkeys share significant auditory similarities with humans.

Purpose of the Study:

• To establish a normative dataset of auditory physiological measures in macaques.
• To provide a baseline for investigating novel diagnostic techniques for hearing impairments.
• To explore the utility of ABRs and DPOAEs in a non-human primate model.

Main Methods:

• Measured auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) in a cohort of male macaque monkeys.
• Utilized both standard (vertex-to-mastoid) and novel (vertex-to-tympanic membrane) electrode montages for ABR recordings.
• Analyzed DPOAE amplitudes and thresholds across various frequencies and stimulus levels.

Main Results:

• DPOAEs showed robust amplitudes up to 10 kHz with high test-retest reliability and lowest thresholds between 2-10 kHz.
• Vertex-to-mastoid ABRs yielded Waves I-IV with lower thresholds, while vertex-to-tympanic membrane montages produced a stronger Wave-I but lacked later waves.
• ABR amplitudes increased with stimulus level and click stimuli, while latencies decreased with increasing stimulus level and frequency.

Conclusions:

• This normative data in macaques serves as a critical baseline for future research on hearing pathologies.
• The findings support the use of ABRs and DPOAEs in non-human primates for auditory research.
• This study lays the groundwork for developing improved physiological measures to detect subtle cochlear damage.