Threshold Equalizing Noise Test Reveals Suprathreshold Loss of Hearing Function, Even in the "Normal" Audiogram Range

Area of Science:

• Audiology
• Otoacoustic Emissions
• Hearing Science

Background:

• The Threshold Equalizing Noise (TEN) test detects cochlear "dead regions" using a pass/fail criterion.
• Sensorineural hearing loss often shows a masked threshold elevation, but typically not enough for a "fail" diagnosis.
• This study explored if intermediate TEN test results correlate with age or noise exposure, suggesting damage beyond outer hair cells.

Purpose of the Study:

• Investigate correlations between intermediate TEN test results and factors like age and noise exposure.
• Determine if the "gray area" of TEN test results provides insights into cochlear damage beyond inner hair cell (IHC) connectivity.
• Clarify the utility of the TEN test for assessing sensorineural hearing loss.

Main Methods:

• 112 participants with normal or mild sensorineural hearing loss (age 32-74) were tested.
• The TEN test was administered at four frequencies (0.75, 1, 3, 4 kHz) and two sensation levels (12, 24 dB SL).
• Cumulative noise exposure and music experience were assessed using the Noise Exposure Structured Interview (NESI).

Main Results:

• A strong positive correlation was found between TEN threshold elevation and absolute hearing threshold across all tested frequencies and levels.
• These correlations persisted even after accounting for noise exposure and music experience.
• Significant correlations were observed even within the "normal" hearing range (absolute thresholds ≤15 dB HL).

Conclusions:

• Sensorineural hearing deficits are detectable with the TEN test even in individuals with clinically "normal" hearing.
• TEN test results between "pass" and "fail" are influenced by factors other than inner hair cell (IHC) function.
• The TEN test should be used for its intended binary "pass" or "fail" diagnostic outcome for IHC-related function.