At present, about 48 million children and young adults have a diagnosis of Autism Spectrum Disorder (ASD). Along with other neurodevelopmental disorders, the prevalence of this condition has seen an increase over the past few decades, aided by the better general awareness and the improvement in the diagnostic criteria.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), children are diagnosed with ASD on the basis of symptoms related to social communication, repetitive behaviour, and restricted interests. There is increasing research on the behavioural and neurophysiological differences between autistic children and typically developing peers, however, little is known about their auditory comorbidities. This is despite up to 90% of individuals with ASD exhibiting some degree of auditory processing difficulty.

In fact, these children may:

·         dislike environments with complex auditory stimuli, for example playgrounds or classrooms

·         appear inattentive in response to auditory information

·         have trouble following verbal instructions

·         find challenges in making use of auditory cues

·         struggle with sound localisation

·         have trouble recalling verbal information

Studies have shown that these difficulties are likely to be associated with disruptive behaviours and challenges in adaptive functioning, demonstrating the need for further research to understand and address auditory processing difficulties in this population.

The aim of our study was to therefore analyse the presence of auditory processing deficits in a group of children diagnosed with ASD.

Subjects presented to a tertiary clinic for Auditory Processing Disorders and underwent an audiological assessment (Pure Tone Audiometry, Transient Evoked Otoacoustic Emissions, Auditory Brainstem Response) as well as auditory processing disorders test battery, including monaural low redundancy tests, dichotic tests, Listening in Spatialised Noise Sentences test, gaps detection tests, pattern recognition tests and additional assessments when deemed necessary.

38 eligible children and adolescents were included in the study (mean age 11.1 ± 2.8 years [range 6-17]).

Interestingly, 75% of children tested scored outside normal limits in the QuickSin, indicating significant difficulties with understanding speech in background noise.

Pattern recognition tests were also found particularly challenging, with 63% of children failing the Duration Pattern subtype and 60% failing Frequency Pattern recognition. These data indicates that about 2 every 3 children had temporal patterning and temporal ordering deficits, which can make speech understanding significantly challenging.

About 60% of children also had abnormal scores in the Listening in Spatialised Noise Sentences (LiSN-S), which assesses auditory stream segregation skills. This refers to the ability to analyse and integrate different components of a complex auditory scenario and results are usually compared against age-averaged norms. 6 children (16%) obtained results consistent with Spatial Processing Disorder, the inability to utilise spatial clues when processing auditory information.

50% of children were found to have deficits in dichotic listening as they failed the Dichotic Digits tests and the Competing Words test, meaning they were unable to integrate different information obtained in each ear separately.

Finally, a significant number of children failed a monaural low redundancy type test (Auditory Figure Ground, Speech in Babble, QuickSIN, Time-compressed and Reverberated words, Filtered Words) with a cumulative percentage of 68%, indicating significant deficits in auditory closure in this population.

In view of these results and taking into account parental and patient-reported symptoms, 29 children (78%) received a diagnosis of Auditory Processing Disorder (APD), as meeting the criteria following BSA guidelines and European consensus on APD. The remaining 9 children were diagnosed with specific auditory deficits.

Although this study included a small subject group, it provides evidence that children with ASD are likely to present a range of auditory processing deficits and abnormalities. Tests for auditory processing are validated and can be effectively administered to children as young as 7 years old. Early identification of auditory processing deficits is crucial for children and young people with autism, allowing to aid tailored therapeutic strategies and interventions, but also enhance their academic outcomes.

While 29 children in this study were diagnosed with APD and would receive appropriate management, the other 9 could still benefit from targeted rehabilitation strategies, such as environmental modifications and auditory training, which have been proven to significantly improve auditory processing skills.

Research indicates that these interventions can lead to measurable improvements in auditory attention, language, and social communication skills. A recent Chinese study revealed notable enhancements in auditory attention and communication skills among children with ASD following auditory integration training. While these findings underscore the benefits of targeted auditory interventions, it is essential to consider individual variability.

In conclusion, these data provide the basis for conducting an auditory processing evaluation in children and young people with Autism Spectrum Disorder. This will help to understand the difficulties these children are faced with when accessing sounds in real life, inform appropriate management strategies, and ultimately improve their quality of life.

 Acknowledgments:

This article is based on unpublished work co-authored by Professor Doris-Eva Bamiou (Ear Institute, University College London) and Professor Vivian Iliadou (Aristotle University of Thessaloniki, Greece).

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