| Language acquisition order of children has attracted much attention and it has been proved that toddlers acquire Mandarin Tone 1 and Tone 4 earlier than Tone 2 and Tone 3.Yet relatively few research has focused on tone perception by elder listeners.Roman Jakobson proposed Regression Hypothesis and claimed that when language loss happens,the sequence of language loss is the opposite of that of language acquisition.Most researchers agreed on the regression nature of language attrition.However,few empirical research was conducted to support this hypothesis.This study explored the impact of different tone or tone continuum types in quiet,SSN and babble conditions on the perception of Mandarin tones across three adult life stages,namely young,middle-aged and senior listeners,testifying the Regression Hypothesis.It specifically discussed the following three research questions:Question 1: How does aging affect Mandarin tone perception?Question 2: How do distinct tone/continuum types influence aging effect?Question 3: How do aging and noise interact to influence perception of different Mandarin tone/continuum types?The current study carried out two tests,namely,typical tone perception and categorical perception of Tones 1-4 and Tones 2-3 continua.Three age groups were involved: 22 young subjects,20 middle-aged subjects,and 20 senior ones.Three listening conditions were concerned,namely quiet,SSN and babble.The experimental materials were four typical Mandarin tones and two tone continua with nine steps synthesized using Praat.Identification accuracy were computed in the first test and category boundary position and category boundary width were calculated in the second test.Based on the statistical analysis,the major findings are summarized below.First,aging exerted detrimental impact on typical tone perception and CP towards Tones 1-4 and Tones 2-3 continua.Young listeners performed the best given their highest identification accuracy in typical tone identification and steepest slopes and narrowest boundary widths in CP.The fact that typical tone perception sensitivity started to take a dive at middle age confirmed that aging is a dynamic process instead of an abrupt change.Second,aging interacted with distinct tone and tone continuum types to cast negative influence on tone perception.Lower accuracy towards Tone 2 and Tone 3 and wider boundary width in perceiving Tones 2-3 continuum suggested that identification of Tone 2,Tone 3 and Tones 2-3 continuum brought about more challenges.This was especially true for middle-aged and senior groups,confirming interaction between aging and distinct tone/continuum types.Furthermore,unsatisfying performance concerning Tone 2,Tone 3 as well as Tones 2-3continuum by middle-aged and senior listeners provided supporting evidence for Regression Hypothesis.Third,aging interacted with noise to exercise adverse effect on perception of different tone/continuum types.Perception performance under quiet condition was better than in noise.Accuracy of Tone 2 and Tone 3 by middle-aged and senior groups plummeted in noise;widths towards Tones 2-3 continuum by two aged groups were wider under two noised conditions.Yet this was not the case under quiet condition nor for other tones or continuum.Moreover,accuracy under babble noise was drastically lower than under SSN,denoting greater impact of babble noise.Results above suggested that aging,Tone 2-and Tone 3-related stimuli,and noise,especially one concerning IM,interacted to impose more challenges on tone perception.Middle-aged and senior adults performed the worst under babble condition in perceiving Tone2,Tone 3 and Tones 2-3 continuum.Generally speaking,these results are in accordance with the prior experimental hypotheses and can be explained by Regression Hypothesis. |
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