Tracking of Noise Tolerance Test Outcomes With the International Speech Test Signal

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Speech Perception

Background:

• The Tracking of Noise Tolerance (TNT) test assesses an individual's ability to tolerate background noise.
• Listener performance on the TNT test can be influenced by the nature of the target signal, whether meaningful speech or nonmeaningful stimuli.

Purpose of the Study:

• To evaluate how using the International Speech Test Signal (ISTS), a nonmeaningful auditory stimulus, affects listener outcomes on the TNT test.
• To examine the relationship between TNT test results, hearing loss, and neurophysiological measures of central auditory inhibition.

Main Methods:

• A single-blind mixed design study involved 23 normal-hearing (NH) and 16 hearing-impaired (HI) older adults.
• Participants completed a modified TNT test using the ISTS as the target signal and dynamic background noise, with performance measured by noise acceptance (TNT_Ave) and noise level fluctuation (excursion).
• Cortical sensory gating magnitudes were recorded as electrophysiological indices of central inhibition.

Main Results:

• Normal-hearing listeners tolerated less noise with ISTS targets compared to English speech, while hearing-impaired listeners showed no difference in noise acceptance.
• Hearing-impaired listeners exhibited greater fluctuation (excursion) in noise levels with ISTS targets, unlike normal-hearing listeners.
• TNT excursion was strongly correlated with pure-tone averages, and sensory gating magnitudes predicted TNT excursion and noise acceptance, regardless of target type.

Conclusions:

• Replacing meaningful speech with nonmeaningful ISTS targets differentially impacts TNT test performance in normal-hearing versus hearing-impaired listeners.
• Comparing TNT results for meaningful and nonmeaningful signals offers insights into acoustic and nonacoustic factors influencing dynamic noise tolerance.
• Neurophysiological measures of central inhibition are linked to an individual's ability to manage fluctuating background noise during auditory tasks.