The effect of impaired speaker’s voice and noise on children's spoken language processing

Background – Past studies indicate that listening to either impaired voice or against background noise may compromise children’s ability to process spoken language. However, the interaction of both factors remains largely unknown. Aim – The aim of this study was to investigate single and combined effects of impaired speaker’s voice and noise on spoken language processing in children (aged 5-6). Methods – First-grade primary school children (n = 53) individually performed two listening tasks: A Minimal-Pair Discrimination task assessing speech perception and a Sentence-Picture Matching Task assessing listening comprehension. Speech stimuli were presented in four conditions: (C1) normal voice and no noise, (C2) imitated impaired voice and no noise, (C3) normal voice and speech-shaped noise, and (C4) imitated impaired voice and speech-shaped noise. Task score per condition was calculated as measure of performance. Results – Irrespective of task, children performed significantly lower when stimuli were presented in a combination of impaired voice and noise (C4) as compared to any other condition. The presence of only one adverse factor (C2 or C3) lowered performance in the speech perception task but not the listening comprehension task. Discussion – Results suggest that when processing speech, young school-aged children are highly vulnerable to the combined effect of impaired speaker’s voice and noise. This could be due to increased auditory masking and reduced cognitive capacity available for linguistic processing. With only a single adverse factor present, children seem able to still use semantic or syntactic context cues for correct interpretation. However, performance drops when such cues are unavailable. Conclusion – Favorable listening conditions may be crucial for children’s processing of spoken language and positive learning outcomes. Particularly in the educational context, where listening is affected by voice quality and noise, measures should be taken to enhance the transmission of the speech signal and reduce noise.