“Auditory Processing and Language Development”

Introduction: Auditory Processing Disorders (APD) and Language Disorders (LD) often co-exist in children, increasing the burden on processing auditory information. Common APD and LD factors include frequency discrimination, phoneme discrimination in noisy environments, and dichotic listening abilities. These factors define the inherent challenges among children with Speech Sound Disorders (SSD).
Purpose: This study aimed to compile and compare the auditory processing profiles of children with SSD and Typically Developing (TD) children using behavioral and electrophysiological measures, and to investigate correlations between these language and auditory processing indices in children with SSD.
Methodology: A descriptive cross-sectional study was conducted involving an initial sample of forty children, sixteen TD and twenty-four with SSD. The sample assessment occurred in four distinct stages. Consenting parents completed the CHAPS and APDQ questionnaires, and their children completed the assessment protocol that comprised of (in randomized order) audiological evaluation, behavioral auditory processing tests using linguistic and non-linguistic stimuli, language assessment focusing on phonology, grammar, syntax, and the cognitive mechanism of working memory, and electrophysiological measurements (early, middle, and late latency auditory evoked potentials). The last phase was completed by a subset of the original participants, resulting in complete data sets for a group of fourteen children with TD and fourteen age-matched children with SSD.
Results: Significant differences between the two groups appeared in language (in first phoneme identification and word repetition) and auditory processing measures (Gap detection 1000Hz and Gap detection in noise 4-7ms, in speech in babble total score, in speech in noise ratio (SNR) 50% and SNR -1, in dichotic words test, in duration pattern sequence and frequency pattern sequence test 4000Hz-6000Hz, and backward digit span). Significant correlations were observed between the auditory processing performance in speech perception in noise, spectral and temporal discrimination, and electrophysiological measures and the language indices phoneme discrimination and rhythm identification. Auditory electrophysiology measures differed between the groups (p<0.001) for the left ear ipsilateral ABR I-V interpeak latency, the left ear contralateral amplitude of MLR wave Na, and for the LLR P1 left contralateral amplitude (p <0.005). Receiver Operating Characteristics (ROC) Analysis showed significant positive discrimination at the level of p<0.005 for the “Gap Detection in Noise 5 (which involves detecting gaps of 4-8 milliseconds in noise)” the “SNR
Minus 1”, and the “Number Memory Reverse”; at the level of p<0.001, significant positive discrimination was found for the “Dichotic Words Right ear 1st”, “Dichotic Words Synchronized”, the “Duration Pattern Sequence”, and the “Frequency Pattern 4000 to 6000Hz”.
Conclusions: Children with a history of SSD were identified by screening questionnaires and had lower performance on dichotic listening, temporal processing, and listening in noise. These findings were enhanced by electrophysiological evidence of diminished processing capacity in the SSD group. These auditory processing characteristics in children with a history of SSD serve as valuable guidance to speech and language professionals to determine specialized referral, targeted diagnostic approaches, and personalized treatment for children with processing difficulties. This work contributes best practices evidence for identification of auditory processing disorders in children with a history of SSD. Our findings suggest a protocol consisting of screening questionnaires, auditory processing tests, and electrophysiological tests in assessing this population. We have created a framework for detection and identification policies by the Republic of Cyprus public health and education authorities.