| Categorical perception(CP)is a significant feature of speech perception,and the development of categorical perception is an important aspect among the improvement of adolescents' language ability.Babble noise is a common background environment in daily speech communication.Most previous studies about the development of CP focused on the English speakers,while the research on the CP development of Chinese phonological contrasts still remains unclear.In addition,the investigations about the effect of noise on phonetic perception are mostly conducted among adults,while few research paid attention to the CP development of adolescents above 10 years old.This paper aims to investigate the categorical perception model and developmental trend of adolescents in the quiet and babble noise conditions by a series of behavioral experiments,trying to explore the effects of babble noise on the development of categorical perception,and the difference between the developmental trajectory of Voice Onset Time(VOT)of aspirated stops and tone perception.And we also hope the results could provide the reference for the speech rehabilitation treatment of special population(e.g.,the adolescents with Autism Spectrum Disorders).In this paper,the research was carried out in the following order:Firstly,we reviewed the relevant previous literature and proposed research ideas and methods.Secondly,we designed the experiment,chose and recorded the speech samples needed for the experiment,including different tones:/ba/55-/ba/35 and different VOTs:/ba/35-/pa/35.The stimuli continua were synthesized by the speech synthesis software TANDEM-STRAIGHT,and the corresponding speech continua containing 0 dB babble noise(3 male and 3 female)were also synthesized.Thirdly,the experimental trials were designed by the psychological experiment design software E-prime 2.0,and were adjusted according to the pilot study.Fourthly,a series of phonetic perception experiments were carried out in 20 adults from northern China,and the categorical perception models of tone and VOT in the quiet and noise conditions were analyzed.Finally,the experimental trials were carried out in 40 Mandarin-speaking adolescents aged 11-18 years(divided into two groups:11-14 years group and 15-18 years group)to explore the developmental trend of the categorical perception models of tone and VOT in the quiet and noise conditions.We investigated the development status and trend of adolescents' categorical perception,as well as the effects of babble noise,through comparing the perceptual models between different adolescent groups and adults in the quiet and babble noise conditions.Through a series of experiments,the results showed that:Firstly,the babble noise had no significant influence on the categorical perception of tone in adults and adolescents aged 15-18,while had a significant impact on the boundary position of tone perception of adolescents aged 11-14,with a boundary movement towards the level tone.And babble noise significantly weakened the ability to perceive VOTs in both adults and adolescents aged 11-18.They all showed wider boundary widths and lower accuracies of between-category discrimination in babble noise condition.Secondly,the development of tone perception was faster than that of VOT perception,and the development of discrimination competence of categorical perception was slower than that of identification ability.What is more,the development of between-category discrimination ability was faster than that of within-category discrimination ability.Adolescents aged 15-18 achieved both adult-like identification and discrimination abilities of tone and VOT.Adolescents aged 11-14 years also could identify tone and VOTs in an adult-like manner,but the boundary position of tone was not robust enough in the noise condition,and the within-category discrimination ability of tone required further development.The discrimination ability of both between-category and within-category had not been mature among adolescents aged 11-14 years. |
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