Hearing Aid Noise-Reduction Programs and Listening Effort
Desjardins and Doherty (2014) evaluated listening effort, with and without a noise reduction algorithm, across 12 adult experienced hearing aid wearers (age range 50 to 74 years, mean=66 years). A dual-task paradigm was used. The primary task was a sentence-in-noise task, presented at two loudness levels. The first level was a moderate listening condition with a performance level of 76 percent and the second was a difficult listening condition” with a 50 percent performance level. To achieve these scores in quiet required various levels to meet the needs and abilities of the individuals. However, the mean signal-to-noise ratios (SNRs) were 4.4 and 1.6 dB, to achieve moderate and difficult conditions (respectively). The second task (of the dual-task paradigm) was a visual tracking test, in which the participant controls/manipulates a mouse as a target moves along an elliptical track. Listening effort was determined based on the change in secondary-task performance, from baseline performance to dual-task performance.
The Starkey S Series BTE was used throughout the study. The S series uses a “modified spectral subtraction-based noise reduction (NR) algorithm” to detect and monitor the acoustic environment and estimates the SNR in each of 16 channels. When noise is detected, the gain in that spectral channel is reduced. The cognitive assessment included a digital version of the Reading Span Test to assess working memory (WM) and the Digital Symbol Substitution Test (DSST) was used to assess speed of processing. A Self-Perceived Ease of Listening measure was used, with ratings from 0 to 100.
The authors state that, “The NR algorithm used in this study significantly reduced” listening effort in the more difficult listening situation. This finding was consistent with previous work which showed “the cognitive benefits of NR were evident only in their most difficult SNR listening condition….” Desjardins and Doherty report that although the “NR algorithm used in the present study did not improve speech recognition scores in babble, it also did not degrade performance….” They conclude, NR significantly reduces listening effort for older patients, NR does not significantly improve word recognition in noise, and listening effort measured in a dual task paradigm is a more sensitive measure (with respect to NR algorithms) than word recognition scores.
For More Information, References, and Recommendations
Desjardins JL, Doherty KA. (2014) The Effect of Hearing Aid Noise-Reduction on Listening Effort in Hearing Impaired Adults. Ear & Hearing 35(5):600-610.
Ng EHN, Rudner M, Lunner T, Pedersen MS, Ronnberg J. (2013) Effects of Noise and Working Memory Capacity on Memory Processing of Speech for Hearing Aid Users. International Journal of Audiology 52:433-441.
Pittman A. (2011) Age-Related Benefits of Digital Noise reduction for Short-Term Word Learning in Children With Hearing Loss. Journal of Speech, Language and Hearing Research 54 (October):1448-1463.
Schum DJ, Beck DL. (2006) Noise Reduction in Advanced Technology Hearing Aids
Stelmachowicz P, Lewis D, Hoover B, Nishi K, McCreery R, Woods W. (2010) Effects of Digital Noise Reduction on Speech Perception for Children with Hearing Loss. Ear & Hearing 31(3):345-355