The effect of language, spatial factors, masker type and memory span on speech-in-noise thresholds in sequential bilingual children

This study considers whether bilingual children listening in a second language are among those on which higher processing and cognitive demands are placed when noise is present. Forty-four Swedish sequential bilingual 15 year-olds were given memory span and vocabulary assessments in their first and second language (Swedish and English). First and second language speech reception thresholds (SRTs) at 50% intelligibility for numbers and colors presented in noise were obtained using an adaptive procedure. The target sentences were presented in simulated, virtual classroom acoustics, masked by either 16-talker multi-talker babble noise (MTBN) or speech shaped noise (SSN), positioned either directly in front of the listener (collocated with the target speech), or spatially separated from the target speech by 90 degrees to either side. Main effects in the Spatial and Noise factors indicated that intelligibility was 3.8 dB lower in collocated conditions and 2.9 dB lower in MTBN conditions. SRTs were unexpectedly higher by 0.9 dB in second language conditions. Memory span significantly predicted 17% of the variance in the second language SRTs, and 9% of the variance in first language SRTs, indicating the possibility that the SRT task places higher cognitive demands when listening to second language speech than when the target is in the listener's first language.