Amblyaudia

Symptoms and signs

Children with amblyaudia have normal hearing sensitivity but struggle with speech perception in noise, sound localization, and binaural unmasking. These difficulties may impair attention to auditory information, potentially affecting language acquisition and academic achievement. Those who lacked auditory stimulation during critical periods may show deficits in vocabulary comprehension and use of verb tenses. Adjudicated adolescents are at significantly high risk for the condition.

Risk factors

Family reports suggest a possible genetic basis for amblyaudia. Abnormal auditory input during the first two years of life may increase risk, though the precise relationship with deprivation timing remains unclear.

Recurrent ear infections (otitis media) are the leading cause of temporary auditory deprivation in young children, degrading signal quality asymmetrically. Aural atresia also causes temporary deprivation. Even after hearing is restored through surgery or spontaneous resolution, children may experience amblyaudia for years.

Physiology

Amblyaudia involves a deficit in binaural integration and is related to brain organization rather than cochlear damage. Animal studies show that early temporary hearing deprivation reduces cell sizes in brainstem nuclei, alters dendrite configuration, and changes neuronal responses. Electrophysiologic studies in children with amblyaudia found uncorrelated N400-P800 responses between ears, indicating an inability to separate information from the non-dominant ear. These children also showed weaker fMRI responses from their non-dominant left ear during dichotic processing.

Diagnosis

Clinical diagnosis follows dichotic listening testing as part of an auditory processing evaluation. Clinicians use the Randomized Dichotic Digits Test and the Dichotic Words Test, which provide normative cut-off scores for dominant and non-dominant ears. Older tests with right/left ear norms may supplement these. A diagnosis is made when performance is normal in the dominant ear and significantly below normal in the non-dominant ear across two or more tests.