Adult listener’s detection thresholds for vowels and two-syllable words in different two-talker maskers

Abstract

There is an increased interest in using natural speech targets and speech maskers to assess infants’ auditory skill development. While providing ecological validity, natural speech is an inherently uncontrolled signal. Discrepancies between existing studies may be the result of differences in the maskers and/or target stimuli used. This study explores adult listener’s detection thresholds for vowels and two-syllable words in three different two-talker maskers to assess the impact of (1) masker characteristics and (2) differences in target signals. Each two-talker masker was created by recording two female speakers reading different passages in monotone, in adult-directed style, or infant-directed style. Silences longer than 300 ms were deleted, and the passages’ root-mean-square amplitudes balanced before combining them. The target stimuli consisted of the vowels /a/, /o/, /e/ and the words “baby” and “ice-cream.” They were spoken by different female talkers in both adult-directed and infant-directed styles. An adaptive two-interval forced choice method was used to estimate threshold. Preliminary results suggest that there are small differences in detection thresholds between the different two-talker maskers. Larger differences are found between the thresholds of different target signals, indicating that discrepancies between existing studies may be due to differences in target stimuli used.