The brain stem response SN10, its frequency selectivity, and its value in classifying neural hearing lesions

Area of Science:

• Audiology and Neuroscience
• Auditory Evoked Potentials

Background:

• The P6 brain stem response is primarily associated with high-frequency hearing (≥ 2 kHz).
• The cortical response N90 is frequency-specific but difficult to record near the hearing threshold.
• A need exists for a reliable audiological measure for low and mid-frequency hearing assessment.

Purpose of the Study:

• To evaluate the slow brain stem response SN10 as a complement to the fast P6 response.
• To assess the SN10's utility in determining hearing ability in low and medium frequencies.
• To investigate the topodiagnostic significance of SN10 in conjunction with P6 and N90.

Main Methods:

• Simultaneous recording of brain stem responses P6 and SN10 in normal hearing individuals and patients with sensorineural hearing loss.
• Stimuli used were tone pips with specific rise/fall and plateau times (approx. 2 ms).
• Comparison of SN10 and P6 responses with subjective hearing thresholds to determine frequency selectivity.

Main Results:

• The SN10 response, unaffected by medicated sleep, provides information on low and medium frequency hearing.
• The mean threshold for the SN10 response was approximately 10 dB above the subjective hearing threshold.
• The frequency selectivity of the SN10 response was confirmed by comparing it with P6 and subjective hearing thresholds.

Conclusions:

• The slow brain stem response SN10 is a valuable complement to the fast P6 response for comprehensive hearing assessment.
• SN10 offers insights into low and mid-frequency hearing sensitivity, extending audiological evaluation capabilities.
• The study demonstrates the topodiagnostic value of SN10, P6, and N90 in cases of neural hearing impairment.