Development of a corpus of Mandarin sentences in babble with homogeneity optimized via psychometric evaluation.

OBJECTIVE To develop a corpus of sentences in babble noise that is suitable for Mandarin-speaking children. Two experiments were conducted with specific aims of (1) developing sentence material that is grammatically and semantically within the linguistic abilities of children; and (2) improving the efficiency of the test by equalizing the relative intelligibility of individual items in sentences. DESIGN AND STUDY SAMPLE Sentences were extracted from spoken material of Chinese children aged between 4 and 5 years of age. The sentences were tested for intelligibility in a four-talker babble by 96 adult native speakers of Mandarin. Psychometric functions were generated, and used for adjusting signal-to-noise ratios of individual items by varying the level of the time-locked babble to equate intelligibility of the target speech. These adjusted stimuli were tested for intelligibility using a different group of 64 adult listeners. RESULTS The signal-to-noise ratio for 50% correct was not different before and after adjustments (- 6.1 dB and - 6.0 dB, respectively). However, there was a significant reduction in standard deviation from 2.3 dB before adjustment to 1.1 dB after adjustment (p < 0.05). CONCLUSIONS The experiments established a corpus of Mandarin BKB-like sentences with four-talker babble as competing noise, in which the test items' homogeneity was optimized via psychometric evaluation (HOPE).