The Influence of the Type of Background Noise on Perceptual Learning of Speech in Noise.

Liping Zhang,Katherine L Roberts,James Harte,Friederike Schlaghecken

doi:10.3389/fnins.2021.646137

Abstract

ObjectivesAuditory perceptual learning studies tend to focus on the nature of the target stimuli. However, features of the background noise can also have a significant impact on the amount of benefit that participants obtain from training. This study explores whether perceptual learning of speech in background babble noise generalizes to other, real-life environmental background noises (car and rain), and if the benefits are sustained over time.DesignNormal-hearing native English speakers were randomly assigned to a training (n = 12) or control group (n = 12). Both groups completed a pre- and post-test session in which they identified Bamford-Kowal-Bench (BKB) target words in babble, car, or rain noise. The training group completed speech-in-babble noise training on three consecutive days between the pre- and post-tests. A follow up session was conducted between 8 and 18 weeks after the post-test session (training group: n = 9; control group: n = 7).ResultsParticipants who received training had significantly higher post-test word identification accuracy than control participants for all three types of noise, although benefits were greatest for the babble noise condition and weaker for the car- and rain-noise conditions. Both training and control groups maintained their pre- to post-test improvement over a period of several weeks for speech in babble noise, but returned to pre-test accuracy for speech in car and rain noise.ConclusionThe findings show that training benefits can show some generalization from speech-in-babble noise to speech in other types of environmental noise. Both groups sustained their learning over a period of several weeks for speech-in-babble noise. As the control group received equal exposure to all three noise types, the sustained learning with babble noise, but not other noises, implies that a structural feature of babble noise was conducive to the sustained improvement. These findings emphasize the importance of considering the background noise as well as the target stimuli in auditory perceptual learning studies.

Highlights

Understanding speech in noise can present a considerable challenge, even for listeners with good hearing
Word identification accuracy differed significantly across the noise conditions [F(1.45, 30.30) = 8.24, p < 0.01, η2 = 0.371], and follow-up pairwise comparisons demonstrated that word identification accuracy was significantly better in the babble noise condition than in the car or rain noise conditions, whereas the latter two did not differ substantially from each other (p = 0.056)
Perceptual training can help listeners to make better lexical judgments about stimuli, process sound information to a higher cognitive order, and reduce participants’ attention to lower-order acoustic features (Loebach and Pisoni, 2008). All of these skills should generalize to other forms of background noise, resulting in the generalization of learning from babble noise to car and rain noise seen in the present study

Summary

Introduction

Understanding speech in noise can present a considerable challenge, even for listeners with good hearing. Noise Affects Perceptual Learning findings could be used as a baseline for further training for related auditory plasticity research in hearing impaired people, such as effects of age and hearing loss level on speech perception in noise (Dubno et al, 1984; Helfer and Wilber, 1990; Anderson et al, 2013; Henshaw and Ferguson, 2013; Alain et al, 2014; Karawani et al, 2016), or speech understanding in children with learning difficulties such as Auditory Processing Disorder (APD) (Bradlow et al, 2003; Ziegler et al, 2005, 2009)

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