In this interview article renowned researcher Dr Frank Musiek looks back on his career and discusses key discoveries about central auditory function in different types and sites of brain disorders, the relationship between APD test patterns and sites of lesion, and the importance of knowledge of neuro-anatomy for clinicians working in neuro-audiology.
The team at SoundSkills congratulates our friend, colleague and APD research collaborator, Dr Suzanne Purdy from the University of Auckland, who has been awarded the American Academy of Audiology International Award for Hearing for 2021 to acknowledge her significant contribution to audiology internationally.
Auditory processing, language, and reading impairment are neurologically entwined. There is considerable research across many domains confirming the hypothesis that disrupted timing of auditory processing is a core deficit in dyslexia.
There is substantial evidence that auditory processing deficits accompany dyslexia, and that there may be at least a partial causative relationship. It is hypothesised that the hearing deficits affect language development, and in turn reading. This brief summary of relevant research evidence is based on a book chapter by Burns (Martha) on “Auditory Processing Disorders and Literacy”.
Auditory processing, language, and reading impairment are neurologically entwined. Some researchers in literacy have begun studying the link between auditory processing disorders and reading problems in school-age children. Recent research has pointed to acoustic, memory, and language functions, including phonological components of language, as core components underlying reading disturbance.
There is considerable research supporting the hypothesis that the underlying core deficit of developmental dyslexia is a phonological processing deficit. But a major neuroscience hypothesis posits an auditory processing deficit at the core of the phonological processing impairment. This hypothesis contends that developmental dyslexia may be caused by a deficit in specific brain circuitry that processes rapidly changing auditory information. This ‘auditory temporal processing deficit hypothesis’ asserts that acquisition of oral language skills can be impaired by an inability to process rapid spectro-temporal characteristics of phonemes.
Many independent neuroscientific studies have corroborated the evidence that rapid auditory processing deficits are a component of reading disturbance. Electrophysiologic studies of children with language and reading problems revealed deficiencies in neural synchrony (timing deficits) in sub-cortical as well as cortical regions that process speech sounds that in turn were related to speech sound perception and measures of learning.
Tallal and colleagues hypothesise that disrupted timing of auditory processing, particularly in the range relevant to phonemes, is a primary deficit underlying dyslexia. Research by Goswami and colleagues has shown that impaired auditory sampling of slow acoustic events in speech may also be a causative effect in dyslexia.
Children with reading impairments also show deficits in speech in noise perception which, along with temporal discrimination problems, are predictive of reading deficit and language delay.
In summary, research across many domains is confirming the hypothesis that auditory processing factors including disrupted timing of auditory processing, particularly in the range relevant to phonemes, are a core deficit in dyslexia. Although the degree to which these disturbances are causative is still debated, the genetic, longitudinal, and electrophysiological studies are beginning to point at least to a partial causative relationship.
Specifically, it appears that rapid auditory processing, at cortical and subcortical levels, represents a core component of phonological awareness. Rapid auditory processing deficits are correlated with problems in phonological decoding of words. The emerging neurophysiological longitudinal evidence points to temporal auditory processing disorders as at least one salient causative factor in some children who continue on to develop language problems and, because of the relationship between language and reading, reading problems as well.
[Comment: There is also evidence that treating auditory processing deficits in children with dyslexia improves phonological awareness and supports treatment of the dyslexia.]
Burns, M, Auditory Processing Disorders and Literacy, Chapter 13, in Auditory Processing Disorders: Assessment, Management and Treatment, 2nd Edition, ed Geffner D and Ross-Swain D, Plural Publishing (2012), 301-317
Musical experience early in life imparts lifelong neuroplasticity.
The argument for early music education takes three general forms. Music boosts brain and cognitive function important for learning, which in turn facilitates success in school. Music training improves educational outcomes, such as graduation rates. And there are also less tangible benefits of music education, such as improved focus, discipline, confidence and even friendships.
The EMC Summer Newsletter 2020 is full of news of the latest EMC research grants and hearing research activities throughout Aotearoa.
In this two part interview Dr Gail Chermak provides an excellent overview of current research-based understanding of (C)APD and its diagnosis and treatment.
20Q: CAPD – Fundamentals
20Q: CAPD – Diagnosis and Intervention
The PhD thesis research of Dr Joan Leung, Adviser: ASD at SoundSkills APD Clinic, showed that children with ASD can improve their communication skills through training to better appreciate prosody, the subtle changes in speech intonation and stress that denote emotion. Use of remote microphone hearing aid systems assisted the prosody perception training and were beneficial to the children in school.
Assessing and training affective prosody perception and production in children with Autism Spectrum Disorder: A Behavioural and neurophysiological Exploration into the Use of Computer-Based Activities and Remote Microphone Hearing Aids for Auditory Processing
Auditory training, language and phonological therapies, and remote microphone hearing aid systems are beneficial for children with APD.
Sharma, M., Purdy, S. C., & Kelly, A. S. (2012). A randomized control trial of interventions in school-aged children with auditory processing disorders. International journal of audiology, 51(7), 506-518.
The purpose of this study (which included participants from SoundSkills APD Clinic) was to demonstrate the efficacy of Auditory Rehabilitation for Interaural Asymmetry (ARIA) to improve dichotic listening scores in children and adolescents diagnosed with amblyaudia and other binaural integration deficits.
Moncrieff, D., Keith, W., Abramson, M., & Swann, A. (2017). Evidence of binaural integration benefits following ARIA training for children and adolescents diagnosed with amblyaudia. International Journal of Audiology, 56(8), 580-588.
One of the most exciting research findings in the treatment of auditory processing disorder (APD) is the neuroplastic benefit of amplification. It is now well established that, over time, amplification with remote microphone hearing aid systems results in improvements in hearing skills of children with APD due to beneficial neuroplastic changes in the brain.