LM213 - Driver(s) for Noise Acceptance in Speech-in-Noise Situations

Abstract: We introduced the Tracking of Noise Tolerance (TNT) test to measure the level of noise that listeners are willing to accept while understanding >90% of the words. Using the Noise Tolerance Domain Test, we were able to uncover that listeners’ noise acceptance on the TNT was driven by their subjective speech intelligibility. Those whose criterion for acceptable intelligibility is higher accept less noise than those who use a lower criterion.

Summary:

A common complaint from hearing aid wearers is using their hearing aids (HA) in noise. Because individual wearers have different degrees of acceptance of noise (among other differences), the same hearing aids, or hearing aids with different features may yield different levels of satisfaction in real life. Thus a tool that can evaluate noise acceptance could help ensure the patient’s use of the hearing aids in noisy environments. And if the tool can predict potential HA satisfaction, it would also make the HA selection (and counseling) process less challenging for the clinicians.

Five years ago, we introduced the Tracking of Noise Tolerance (TNT) test as a tool to measure noise acceptance. This test uses fixed speech levels (at 75 and/or 82 dB SPL) and listeners adjust the level of a competing background noise to a maximum level that they can put up with while still understanding over 90% of the speech passage. We have used the test on hearing-impaired and normal- hearing subjects and demonstrated its test-retest reliability and sensitivity to reveal quantitative differences in processing between hearing aids. We showed that people who have a higher tolerance for noise are also more satisfied with their hearing aids in loud, noisy situations.

In the last two years, we were interested to understand WHY listeners performed the manner they did on the TNT. To do that, we formalized the TNT test development and measured the subjective and objective performance-intensity functions of the TNT speech materials over a range of signal-to-noise ratios (SNRs) in normal-hearing listeners and hearing-impaired listeners. We demonstrated that subjective intelligibility at the valleys of the TNT tracking is around the 90% criterion we instructed the listeners.  More recently, we adapted the Noise Tolerance Domain test (NTDT) proposed by Mackersie et al (2020) to study the domain criteria that listeners used at their TNT threshold and at SNRs surrounding that threshold. During the NTDT, listeners compared which domain criteria (speech interference, loudness, distraction and annoyance) was more important in their noise acceptance decision and rated the effect of that domain in their judgment. The weighted rating for each domain was then plotted against the listeners’ subjective speech intelligibility at the test SNR/level. The results showed that when the subjective speech intelligibility was poor ( < 50%), listeners typically used speech interference and loudness discomfort as the domain to base their decision. As intelligibility improved, listeners weighted distraction and annoyance more in their noise acceptance decisions. Furthermore, a regression analysis showed that the subjective intelligibility scores at the TNT threshold predicts if the listener weighs acoustic factor or emotional/cognitive factor higher in their noise acceptance decisions.
In this presentation, we will share the details of our latest studies and outline a clinical protocol to use the TNT test so clinicians may use this information effectively.