Effects of an Auditory Lateralization Training in Children Suspected to Central Auditory Processing Disorder

BACKGROUND AND OBJECTIVES: Central auditory processing disorder [(C)APD] refers to a deficit in auditory stimuli processing in nervous system that is not due to higher-order language or cognitive factors. One of the problems in children with (C)APD is spatial difficulties which have been overlooked despite their significance. Localization is an auditory ability to detect sound sources in space and can help to differentiate between the desired speech from other simultaneous sound sources. Aim of this research was investigating effects of an auditory lateralization training on speech perception in presence of noise/competing signals in children suspected to (C)APD. SUBJECTS AND METHODS: In this analytical interventional study, 60 children suspected to (C)APD were selected based on multiple auditory processing assessment subtests. They were randomly divided into two groups: control (mean age 9.07) and training groups (mean age 9.00). Training program consisted of detection and pointing to sound sources delivered with interaural time differences under headphones for 12 formal sessions (6 weeks). Spatial word recognition score (WRS) and monaural selective auditory attention test (mSAAT) were used to follow the auditory lateralization training effects. RESULTS: This study showed that in the training group, mSAAT score and spatial WRS in noise (p value≤0.001) improved significantly after the auditory lateralization training. CONCLUSIONS: We used auditory lateralization training for 6 weeks and showed that auditory lateralization can improve speech understanding in noise significantly. The generalization of this results needs further researches.

Auditory lateralization ability in children with [central] auditory processing disorder

The aim of the present study was to assess the auditory lateralization ability in children with [central] auditory processing disorder. Participants were divided in two groups: 15 children with Central Auditory Processing Disorder [8-10 years] and 80 normal children [8-11 years] from both genders with pure-tone air-conduction thresholds better than 20 dB HL bilaterally and interaural pure tone threshold difference better than 5 dB . All subjects had normal IQ and normal otoscopy: In the present study 9 imaginary positions were simulated in horizontal plane by Interaural Time Difference [ITD] and Interaural Intensity Difference [IID] to evaluate the auditory lateralization performance in normal and children with [central] Auditory Processing Disorder [C] APD. Lateralization performance were determined by ITD ranging from -880 to +880 microsecond and IID ranging from -10 to +10 dB for high pass and low pass noise[2 kHz cut off point]. Boltzmann function was used to describe the auditory lateralization performance and Independent Samples T-test was used to compare the two groups. According to Boltzmann function two major types of abnormalities were revealed in the lateralization performances: 1- completely disoriented, 2- side-oriented. 86.6% of [C] APD children showed significant increase in mean of test errors compared with normal ones [p<0.001]. The study supports the hypothesis that most children with [C] APD have poor auditory lateralization and abnormal processing of binaural cues