Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder

Background: This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). Methods: The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9–11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. Results: The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. Conclusion: The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information

Auditory Spectro-Temporal Modulation Training in Children With Auditory Processing Disorder

Objectives: Auditory processing disorder (APD) is due to the deficits in perceptual processing of acoustic information in the auditory system, characterized by poor speech perception of noise, regardless of normal hearing. The variability in speech function of APD children can be partly explained by changes in the encoding of spectro-temporal modulations (STMs) which have been overlooked, despite their significance. Given that enhancing STM sensitivity and its processing can be an appropriate way to improve the listener’s ability to retrieve and integrate speech segments covered by noise, we decided to evaluate the effects of STM-based auditory training on speech perception in noise and the reliability of this training in children with APD. Methods: Thirty-five children with APD (8-12 years old) were randomly divided into the training (n=17) and control groups (n=18) to evaluate the effectiveness and reliability of STM training on speech in noise perception. The intervention group was trained to detect STM by 120 trials every day for ten days. The STM detection thresholds and speech perception in noise were evaluated before and immediately after the finalization of formal training sessions in both groups. To address the training reliability, the tests were repeated one month after practice in the training group.  Results: Following the completion of STM auditory training, the trained APD children improved notably in STM detection tasks and speech in noise tests (P0.05), but the word in the noise test, especially in the right ear, was not retained (P<0.05). Discussion: Auditory spectro-temporal modulation training can lead to better processing of STM modulation. Its effects can be generalized to higher-order processing, such as speech perception in noise. Auditory training based on STM processing enhancement can play an essential role in improving speech comprehension in the noise abilities of children with APD