Development of Speech Perception.ppt

1、Development of Speech Perception,Issues in the development of speech perception,Are the mechanisms peculiar to speech perception evident in young infants? Do infants, children and adults use the same information to identify speech? How long does it take for speech perception to mature?,Overview of l

2、ecture,Development of speech discrimination Infants Preschoolers School-age children Effects of experience on speech discrimination,Categorical speech perception,da-ga discrimination demonstration,F2 transition duration,% “ga” responses,1 4 7 10,boundary,Categorical speech perception,boundary,F2 Tra

3、nsition duration,duration threshold,Do infants discriminate speech contrasts categorically?,Voice onset time,% “pa” responses,1 4 7 10,boundary,Infants discriminate speech contrasts categorically,Infants discriminate many phonetic contrasts,Consonants categorical voicing, place, manner Initial, medi

4、al, final position Vowels continuous (not categorical) Despite variation in intonation or speaker Non-native phonetic contrasts,Context-dependent discrimination,Transition duration,% “wa” responses,Does anything about speech perception develop after birth?,I hate it when my brother uses incorrect gr

5、ammar!,How can infants discriminate speech if they have immature hearing?,Basic aspects of hearing (frequency, intensity, temporal coding) probably mature by 6 months. Multiple acoustic cues to phonetic contrasts; infants and adults could use different cues. “Easy” distinctions used in many studies

6、dont test limits of infants hearing.,A test of the detail in acoustic representation of speech,The acoustic representation of speech becomes more detailed,Infants VOT threshold,/ba/ v. /pa/ 5.5-11.5 months and adults Conditioned head-turn procedure Adaptive thresholds,How do infants figure out where

7、 one word ends and another begins?,Evenininfantdirectedspeechfewutterancesconsistofisolatedwordsinanalyzingtheinputheardbyaninfantbetweensixandninemonthsvanderwiierfoundthatexcludinggreetingsvocativesandfillersonlyaboutsevenpercentofthespeechconsistedofonewordutterancesthustolearnthewordsoftheirnati

8、velanguageinfantsmusthavesomeabilitytosegmentwordsfromfluentspeechasdiscussedearlierpausesrarelyoccurbetweenwordsinfluentspeech.,Huh?,Cues that adults can use,Phonotactic regularity: “slo”, not “slx” Allophonic variations: t starts, th ends “correlations” between sounds: b+a+L happen together a lot.

9、 In some languages, words tend to follow a certain stress pattern (e.g., strong-weak in English). Once you know some words, you can separate those from other words.,Testing segmentation in infants,Ball spoon truckman seat baby truck ball,Spoon spoon ,Chair chair ,Some landmarks in developing sensiti

10、vity to native language sound organization,Do children use acoustic cues in speech like adults?,VC transition Vowel duration Burst frequency Etc.Childrens use of formant transitions and static spectral information in speech,Booed or Boot?,Cab or Cap?,Childrens use of formant transitions and static s

11、pectral information in speech,Childrens use of formant transitions and static spectral information in speech,Dynamic cues or easiest to hear?,Dynamic cues or easiest to hear?,Easiest to hear?,Sometimes spectrally dissimilar is better,Sometimes children are like adults,Are 6-year-olds like adults in

12、speech perception?,Even 12-year-olds are not like adults in speech perception,Full cues,Single cues,Conclusions,Early in infancy, auditory immaturity may limit speech perception. Even though infants and children can discriminate speech sounds, they use different cues than adults do. Even school-age

13、children have difficulty switching from one cue to another in speech discrimination when listening conditions change.,Overview of effects of experience on speech perception,Nature v. Nurture?,Its always both.,We know experience hearing speech changes speech perception.,Children learn to speak the la

14、nguage they hear around them. Adults have difficulty discriminating and producing some contrasts in nonnative languages.,How could experience with speech affect development of speech perception?,Hardly at all Attunement Maintenance Facilitation Induction,Critical period,Effect of experience,Age,Main

15、tenance role of experience,Later research showed that,Sometimes 12-month-olds lose the nonnative discrimination, but adults are able to discriminate. Sometimes the nonnative discrimination seems unaffected by experience. The role of experience seems to be to reorganize perception in a way that makes

16、 it hard to discriminate nonnative contrasts. With the right kind of experience, adult listeners can learn to make nonnative discriminations.,Reorganization of perception,Cue 1,Cue 2,Cue 1,Cue 2,Reorganization of perception,Cue 1,Cue 2,Cue 1,Cue 2,Reorganization of perception,Cue 1,Cue 2,Cue 3,Cue 4

17、,Critical period?,Effect of experience,Age,12 years?,Effects of experience on development of speech perception,Experience with native speech leads to a reorganization of perception. The way that the reorganization will affect performance depends upon the relationship between the original speech categories and the native speech categories. Examples of no influence, attunement, maintenance and facilitation of speech perception by experience hearing speech have been identified.,