The Hearing Brain

By Jennifer B. Shinn

This article is a part of the May/June 2020, Volume 32, Volume 3, Audiology Today issue.

Audiologists are regularly faced with the patient who presents to their office with a variety of hearing complaints. They often report significant difficulty hearing, particularly in background noise. These hearing difficulties negatively affect them both occupationally and socially. However, upon assessment, the pure-tone audiogram results demonstrate “normal” peripheral hearing sensitivity. These are perhaps not the anticipated results, given the patient’s reported difficulties. In this situation, the question we should ask ourselves is: Does normal hearing on the audiogram in fact mean normal hearing? The answer is no.

Hearing is a complicated process. As audiologists, we are well versed in anatomy and physiology of the peripheral auditory system and the evaluation of hearing sensitivity. Unfortunately, many individuals lack training in central auditory function and its assessment. As a result,   we all too often forget about the role that the brain plays in our ability to hear.

As a profession, admittedly few audiologists evaluate central auditory function (Chermak et al, 2007) and those who do often focus on the pediatric population. While most individuals relate auditory processing disorders to children, this should not be the case. Many adults present with auditory processing deficits that are often overlooked because of their age and normal hearing sensitivity.

The central auditory nervous system is an intricate and complicated neural network that plays a critical role in hearing. Auditory information must be preserved and transferred through an array of cells, nuclei, and pathways. If there is an interruption in transmission of the signal, the auditory system may not be able to efficiently or effectively process meaningful input, resulting in measurable perceptual deficits. This often manifests from impairment in one’s ability to code intensity, frequency, and/or temporal elements of auditory input.

Deficits in this neural pathway can result in a myriad of complaints. While the most prevalent is difficulty in hearing in complicated or challenging listening environments, other perceptual deficits reported may include difficulty localizing sound sources, changes in sound quality (i.e., distortion), and poor auditory discrimination.