Effect of Mild Hearing Loss on Auditory Perception in Complex Environments

Dawna Lewis, PhD

Children with mild bilateral hearing loss and children with unilateral hearing loss experience greater speech-perception difficulties in noise and reverberation than children with normal hearing, as well as potential delays in speech and language development and educational progress. Mild bilateral hearing loss and unilateral hearing loss may reduce the quantity and quality of auditory experiences. The combined effects of acoustic environment, elevated hearing thresholds, and the lack or limited use of amplification are likely to produce inconsistent audibility during auditory-skill and speech/language development. If these abilities are immature, children with mild bilateral hearing loss and unilateral hearing loss may need to devote greater cognitive effort to understanding speech, leaving fewer resources for other complex processes. The availability and use of visual information also may impact speech understanding for these children. Research examining auditory and audiovisual speech perception in complex listening conditions is limited in children with mild bilateral hearing loss and unilateral hearing loss. This study was designed to document how these children compare to peers with normal hearing on these skills. The overall goal was to improve communication access in complex listening conditions for children with mild bilateral hearing loss or unilateral hearing loss by evaluating the influence of dynamic features of multi-source environments in isolation and in combination that impact speech understanding. The project consisted of two aims: first, to identify auditory and audiovisual factors that influence comprehension in complex acoustic environments for children with minimal/mild hearing loss; and second, to examine comprehension in complex acoustic environments for children with minimal/mild hearing loss. 

The results of these studies indicate that children with mild bilateral hearing loss and unilateral hearing loss perform more poorly on tasks that require them to locate talkers in complex acoustic conditions. Depending on the task and environment, performance differences were observed between the two groups of children with hearing loss. This information adds to our understanding of the use of auditory and multimodal skills for listening in complex environments and is a first step toward identifying those children with mild bilateral hearing loss or unilateral hearing loss who may be at greater risk for difficulties.

To appreciate the interaction between auditory skills and real-world listening, it is important to examine performance in realistic environments during complex listening tasks. Laboratory studies only provide an approximation of these environments and testing in actual classrooms lacks experimental control due to their active nature. This project also developed learning tasks representative of typical classroom activities for use in novel laboratory simulations of plausible classroom environments. Studies in our lab have indicated that children with mild bilateral hearing loss and unilateral hearing loss perform more poorly than peers with normal hearing during these tasks. New stimuli have been developed to allow continuation of studies examining performance during complex tasks. Results of an exploratory study of virtual reality technology suggest that it is a viable option for use in simulating real-world visual environments in laboratory settings. The use of complex listening tasks and environments can provide performance information that will lead to changes in the ways children with mild bilateral hearing loss and unilateral hearing loss are served.