Amblyaudia
Amblyaudia (amblyos- blunt; audia-hearing) is a term coined by Dr. Deborah Moncrieff to characterize a specific pattern of performance from dichotic listening tests. Dichotic listening tests are widely used to assess individuals for binaural integration, a type of auditory processing skill. During the tests, individuals are asked to identify different words presented simultaneously to the two ears. Normal listeners can identify the words fairly well and show a small difference between the two ears with one ear slightly dominant over the other. For the majority of listeners, this small difference is referred to as a "right-ear advantage" because their right ear performs slightly better than their left ear. But some normal individuals produce a "left-ear advantage" during dichotic tests and others perform at equal levels in the two ears. Amblyaudia is diagnosed when the scores from the two ears are significantly different with the individual's dominant ear score much higher than the score in the non-dominant ear [1] Researchers interested in understanding the neurophysiological underpinnings of amblyaudia consider it to be a
Symptoms and signs
Children with amblyaudia experience difficulties in speech perception,[4] particularly in noisy environments, sound localization,[5] and binaural unmasking[6][7][8][9][10] (using interaural cues to hear better in noise) despite having normal hearing sensitivity (as indexed through pure tone audiometry). These symptoms may lead to difficulty attending to auditory information causing many to speculate that language acquisition and academic achievement may be deleteriously affected in children with amblyaudia. A significant deficit in a child's ability to use and comprehend expressive language may be seen in children who lacked auditory stimulation throughout the critical periods of auditory system development. A child suffering from amblyaudia may have trouble in appropriate vocabulary comprehension and production and the use of past, present and future tenses. Amblyaudia has been diagnosed in many children with reported difficulties understanding and learning from listening[11][12][13] and adjudicated adolescents are at a significantly high risk for amblyaudia (Moncrieff, et al., 2013, Seminars in Hearing).
Risk Factors
Families report the presence of amblyaudia in several individuals, suggesting that it may be genetic in nature. It is possible that abnormal auditory input during the first two years of life may increase a child's risk for amblyaudia, although the precise relationship between deprivation timing and development of amblyaudia is still unclear. Recurrent ear infections (otitis media) are the leading cause of temporary auditory deprivation in young children.[14][15][16] During ear infection bouts, the quality of the signal that reaches the auditory regions of the brains of a subset of children with OM is degraded in both timing and magnitude.[17][18] When this degradation is asymmetric (worse in one ear than the other) the binaural cues associated with sound localization can also be degraded. Aural atresia (a closed external auditory canal) also causes temporary auditory deprivation in young children. Hearing can be restored to children with ear infections and aural atresia through surgical intervention (although ear infections will also resolve spontaneously). Nevertheless, children with histories of auditory deprivation secondary to these diseases can experience amblyaudia for years after their hearing has been restored.[6][19]
Physiology
Amblyaudia is a deficit in binaural integration of environmental information entering the auditory system. It is a disorder related to
An electrophysiologic study demonstrated that children with amblyaudia (referred to then as a "left-ear deficit") were less able to process information from their non-dominant ears when competing information is arriving at their dominant ears. The N400-P800 complex[31] showed a strong and highly correlated response from the dominant and non-dominant ears among normal children while the response from children with amblyaudia was uncorrelated and indicated an inability to separate information arriving at the non-dominant ear from the information arriving at the dominant ear. The same children also produced weaker fMRI responses from their non-dominant left ears when processing dichotic material in the scanner.[32]
Diagnosis
A clinical diagnosis of amblyaudia is made following
Treatments
A number of computer-based auditory training programs exist for children with generalized Auditory Processing Disorders (APD). In the visual system, it has been proven that adults with amblyopia can improve their visual acuity with targeted brain training programs (perceptual learning).[37] A focused perceptual training protocol for children with amblyaudia called Auditory Rehabilitation for Interaural Asymmetry (ARIA) was developed in 2001[38] which has been found to improve dichotic listening performance in the non-dominant ear and enhance general listening skills. ARIA is now available in a number of clinical sites in the U.S., Canada, Australia and New Zealand. It is also undergoing clinical research trials involving electrophysiologic measures and activation patterns acquired through functional magnetic resonance imaging (fMRI) techniques to further establish its efficacy to remediate amblyaudia.[citation needed]
See also
- Amblyopia
- Auditory processing disorder
- Binaural fusion
- Hearing
- Otitis media
- Aural atresia
References
- ^ Moncrieff, Keith, Abramson, & Swann (2016) Diagnosis of amblyaudia in children referred for auditory processing assessment. International journal of audiology, 55(6), 333-345.
- PMID 21607783.
- S2CID 2692071.
- S2CID 35288270.
- S2CID 15538878.
- ^ PMID 7619408.
- PMID 1877902.
- PMID 8725518.
- PMID 1863436.
- PMID 12943367.
- PMID 12371660.
- S2CID 22794514.
- PMID 17647215.
- PMID 9789665.
- PMID 2732519.
- PMID 9631643.
- PMID 8436453.
- PMID 21073935.
- S2CID 4762842.
- PMID 880104.
- S2CID 10194727.
- S2CID 38143118.
- S2CID 27428850.
- S2CID 9227670.
- S2CID 33997388.
- S2CID 1640696.
- PMID 925728.
- PMID 925729.
- S2CID 6730028.
- PMID 20223206.
- PMID 15484601.
- PMID 18637408.
- PMID 19927683.
- PMID 26218052.
- ^ Moncrieff, Keith, Abramson, & Swann, 2016. Diagnosis of amblyaudia in children referred for auditory processing assessment. International journal of audiology, 55(6), 333-345.
- S2CID 37665256.
- PMID 19250947.
- S2CID 22268018.