The Lingering Impact of Middle Ear Infections on Auditory Processing

Although middle ear infections are sometimes dismissed as a typical childhood illness, they can have a long term impact on a child’s ability to listen and comprehend speech. Middle ear infections may influence auditory development by rewiring the parts of the brain responsible for processing sound. This may result in the development of hearing deficits that last long after the infection clears. This article addresses the significant impact that middle ear infections can have on a child’s listening skills.

The first three years of life are critical for the brain’s development for processing speech sounds. As the child is exposed to speech in their environment the brain is putting together a toolkit of phonemic references, each of which represents a distinct speech sound in the language. These references are essential for distinguishing sounds and understanding speech. However, when a child experiences repeated middle ear infections, it can sound like listening through water. Throughout the different stages of the infection the clarity may vary, distorting the sound perception and resulting in inconsistent auditory input. Even after the infection clears, middle ear fluid can remain for months, often unnoticed because the child may not experience any pain, fever, or signs of congestion.

To further complicate things, during this early stage of life, children face the challenge of discerning slight variations within the way a phoneme sounds spoken by different genders and speakers with different accents. Additionally, they must recognize the influences of surrounding sounds that cause slight differences but still stay within the boundaries established for each speech sound.

Due to the inconsistency in speech sound perception, the brain cannot precisely map the phonemic boundaries to develop references for each sound. This causes the brain to eventually develop vague or overlapping representations of similar sounding speech sounds. Procedures such as pressure equalization ear tubes can reduce fluid accumulation, but they do not remove the child’s internalized sound references ingrained in the child’s mind.

The variations within the way speech sounds are perceived puts these children at high risk for developing an auditory processing disorder (APD), a type of listening problem that does not occur in the ear but rather in the pathways that transmit signals from the hearing nerve to auditory networks in the brain. As a result, individuals with APD struggle to process sound accurately and efficiently because the brain struggles to analyze the perceived sounds and turn sound into useful information. However, these listening difficulties are often overlooked since children can hear soft sounds and usually pass a basic hearing test.

There are different types of auditory processing disorders, but two most common types in children with a history of chronic ear infections are a lazy ear and a spatial processing disorder. Both of these types of APD are believed to result from a problem with how the brain adjusts to hearing changes.

If the quality of sound in one ear is significantly better than the other ear, children can develop a lazy ear, where the stronger pathway overwhelms the weaker pathway. This affects the ability of the ears to coordinate effectively. Since all features arriving at the two ears are not preserved, integrated and accurately coded by the auditory system, it degrades the quality of sound reaching the auditory regions of the brain. A spatial processing disorder can result due to abnormal functioning in the mechanisms that use spatial cues to suppress unwanted sounds from different directions. Both conditions are types of auditory processing disorder that can be completely remediated. However, when overlooked and untreated, they can cause speech perception deficits, difficulty understanding in challenging listening situations (such as when background noise is present), sensitivity to environmental sounds, and academic struggles.

Auditory training helps the brain remap the phonemic boundaries that it developed for each distinct speech sound. This training helps children overcome difficulties with auditory processing brought on by early ear infections. By addressing and treating auditory processing issues early, it can prevent long-lasting effects on a child’s communication abilities, highlighting the importance of not dismissing middle ear infections as merely a common childhood condition.