Age differences in binaural and working memory abilities in school-going children.

Abstract

Binaural hearing is the interplay of acoustic cues (interaural time differences: ITD, interaural level differences: ILD, and spectral cues) and cognitive abilities (e.g., working memory, attention). The current study investigated the effect of developmental age on auditory binaural resolution and working memory and the association between them (if any) in school-going children. Fifty-seven normal-hearing school-going children aged 6-15y were recruited for the study. The participants were divided into three groups: Group 1 (n=17, Mage=7.1y±0.72y), Group 2 (n=23; Mage=10.2y±0.8y), Group 3 (n=17; Mage: 14.1y ±1.3y). Group 4, with normal hearing young adults (n=20; Mage=21.1y± 3.2y), was included for comparing the maturational changes in former groups with adult values. Tests of binaural resolution (ITD and ILD thresholds) and auditory working memory (forward and backward digit span and 2n-back digit) were administered to all the participants. Results indicated a main effect of age on spatial resolution and working memory, with the median of lower age groups (Group 1 & Group 2) being significantly poorer (p<0.01) than the higher age groups (Group 3 & Group 4). Groups 2, 3, and 4 performed significantly better than Group 1 (p<0.001) on the forward span and ILD task. Groups 3 and 4 had significantly better ITD (p=0.04), backward span (p=0.02), and 2n-back scores than Group 2. A significant correlation between scores on working memory tasks and spatial resolution thresholds was also found. On discriminant function analysis, backward span and ITD emerged as sensitive measures for segregating older groups (Group 3 & Group 4) from younger groups (Group 1 & Group 2). The present study showed that the ILD thresholds and forward digit span mature by nine years. However, the backward digit span score continued to mature beyond 15y. This finding can be attributed to the influence of auditory attention (a working memory process) on the binaural resolution, which is reported to mature till late adolescence.