Infant speech-sound discrimination in noise

Abstract

Infant ability to discriminate a speech-sound pair in noise was assessed using the visual reinforcement infant speech discrimination procedure. Sixteen infants between 7 and 12 months were tested on the /ba-ga/ contrast at four S/N's (− 8, 0, 8, and 16 dB). A group of young-adult control subjects was tested also at four S/N's (− 12, − 8, − 4, and 0 dB). The noise was continuously present at 48 dB SPL. Group psychometric functions revealed that infants required a more favorable S/N than adults to achieve given levels of performance. The adult subjects and 14 of the 16 infants were also tested using a discrimination-threshold procedure in which the stimulus intensity was varied adaptively (1-up/1-down). The adaptive discrimination procedure provided, for both groups, estimates of performance that are in good agreement with those from the performance versus S/N functions that were developed using the more time-consuming method of trial blocks at fixed S/N's. [Work supported by DRF and NIH POI NS16337.]