Switching Attention and Integration of Binaural Information: Effects of Speech Material and Masker Types on Perception of Alternated and Interrupted Speech in Children

There is much current interest in Auditory Processing Disorder (APD) in children, not least because of suspicions that APD may lead to poor school performance. Children suspected of APD typically present with difficulties in understanding speech in noisy environments despite a normal audiogram. APD may thus arise from higher-level auditory cognitive deficits. We have been investigating a task that appears to exploit some cognitive aspects of listening not probed by simpler tasks, and assesses a listener’s ability to switch attention and integrate short-term auditory information across the two ears.

A masker is interrupted (fixed modulation rate=5 Hz) and alternated between the ears out-of-phase with an interrupted target speech, resulting in alternated segments of both target and masker signals between the two ears, with only one stimulus present in each ear at any given time. Two types of target sentences were used: ‘everyday’ sentences like, ‘The clown had a funny face’, and a children’s version of the CRM sentences, ‘Show the <animal> where the <colour> <digit> is’. We also varied masker type: unrelated connected-speech, spoken in an unfamiliar/familiar language, by talkers from the opposite sex to the target, and a speech-spectrum-shaped-noise modulated with the envelope of the speech maskers. Additionally, the CRM-like sentences were used as maskers with CRM-like targets.

Preliminary data from 7-13 year old children suggests poorer performance in the APD group compared to typically developing controls, particularly when both target and masker originate from the CRM-like corpus. Such a configuration may introduce more informational masking and thus increase the demand on higher-level auditory cognitive function, than in the everyday sentences where semantic similarities between the masker and target are minimal. A larger data set will allow assessment of the extent to which performance in this task is correlated with other tasks, such as a standard speech-in-noise task.