Acoustic Continua and Phonetic Categories

Frequency - Tones

Frequency - Complex Sounds

Frequency - Vowels Vowels combine acoustic energy at a number of different frequencies Different vowels ([a], [i], [u] etc.) contain acoustic energy at different frequencies Listeners must perform a ‘frequency analysis’ of vowels in order to identify them (Fourier Analysis)

Frequency - Male Vowels

Frequency - Female Vowels

Synthesized Speech Allows for precise control of sounds Valuable tool for investigating perception

Timing - Voicing

Voice Onset Time (VOT) 60 msec

English VOT production Not uniform 2 categories

Perceiving VOT ‘Categorical Perception’

Discrimination Same/Different

Discrimination Same/Different 0ms 60ms

Discrimination Same/Different 0ms 60ms Same/Different

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms Why is this pair difficult?

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms Why is this pair difficult? (i) Acoustically similar? (ii) Same Category?

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms Why is this pair difficult? (i) Acoustically similar? (ii) Same Category? A More Systematic Test

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms A More Systematic Test 0ms 20ms 40ms 20ms 40ms 60ms

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms A More Systematic Test 0ms 20ms 40ms 20ms 40ms 60ms DT D T T D Within-Category Discrimination is Hard

Cross-language Differences R L

R L R L

Cross-Language Differences English vs. Japanese R-L

Cross-Language Differences English vs. Hindi alveolar [d] retroflex [D] ?

Russian -40ms -30ms -20ms -10ms 0ms 10ms

Development of Speech Perception 3 Classics

Development of Speech Perception Unusually well described in past 30 years Learning theories exist, and can be tested… Jakobson’s suggestion: children add feature contrasts to their phonological inventory during development Roman Jakobson, Kindersprache, Aphasie und allgemeine Lautgesetze, 1941

Developmental Differentiation 0 months 6 months12 months18 months Universal Phonetics Native Lg. Phonetics Native Lg. Phonology

#1 - Infant Categorical Perception Eimas, Siqueland, Jusczyk & Vigorito, 1971

Discrimination Same/Different 0ms 60ms Same/Different 0ms 10ms Same/Different 40ms A More Systematic Test 0ms 20ms 40ms 20ms 40ms 60ms DT D T T D Within-Category Discrimination is Hard

English VOT Perception To Test 2-month olds Not so easy! High Amplitude Sucking Eimas et al. 1971

General Infant Abilities Infants’ show Categorical Perception of speech sounds - at 2 months and earlier Discriminate a wide range of speech contrasts (voicing, place, manner, etc.) Discriminate Non-Native speech contrasts e.g., Japanese babies discriminate r-l e.g., Canadian babies discriminate d-D

Universal Listeners Infants may be able to discriminate all speech contrasts from the languages of the world!

How can they do this? Innate speech-processing capacity? General properties of auditory system?

What About Non-Humans? Chinchillas show categorical perception of voicing contrasts!

#2 - Becoming a Native Listener Werker & Tees, 1984

When does Change Occur? About 10 months Janet Werker U. of British Columbia Conditioned Headturn Procedure

When does Change Occur? Hindi and Salish contrasts tested on English kids Janet Werker U. of British Columbia Conditioned Headturn Procedure

What do Werker’s results show? Is this the beginning of efficient memory representations (phonological categories)? Are the infants learning words? Or something else?

#3 - What, no minimal pairs? Stager & Werker, 1997

A Learning Theory… How do we find out the contrastive phonemes of a language? Minimal Pairs

Word Learning Stager & Werker 1997 ‘bih’ vs. ‘dih’ and ‘lif’ vs. ‘neem’

Word learning results Exp 2 vs 4

Why Yearlings Fail on Minimal Pairs They fail specifically when the task requires word-learning They do know the sounds But they fail to use the detail needed for minimal pairs to store words in memory !!??

One-Year Olds Again One-year olds know the surface sound patterns of the language One-year olds do not yet know which sounds are used contrastively in the language… …and which sounds simply reflect allophonic variation One-year olds need to learn contrasts

Maybe not so bad after all... Children learn the feature contrasts of their language Children may learn gradually, adding features over the course of development Phonetic knowledge does not entail phonological knowledge Roman Jakobson,

Connecting Hearing & Speaking

Auditory [ba] + Visual [ga] = Perceptual [da] McGurk Effect

Connecting Hearing & Speaking Auditory [ba] + Visual [ga] = Perceptual [da]

Evidence for connection Infants know connection between visual and auditory speech stimuli Mix and match [a] vs. [i]

Questions about Development

6-12 Months: What Changes?

Structure Changing Patricia Kuhl U. of Washington

Structure Adding Evidence for Structure Adding (i) Some discrimination retained when sounds presented close together (e.g. Hindi d-D contrast) (ii) Discrimination abilities better when people hear sounds as non-speech (iii) Adults do better than 1-year olds on some sound contrasts Evidence for Structure Changing (i) No evidence of preserved non-native category boundaries in vowel perception

Sources of Evidence Structure-changing: mostly from vowels Structure-adding: mostly from consonants Conjecture: structure-adding is correct in domains where there are natural articulatory (or acoustic) boundaries

So how do infants learn…? Surface phonetic patterns

So how do infants learn…? Phoneme categories and alternations –Perhaps more like a phonologist than like a LING101 student - look directly for systematic relations among phones –Gradual articulation of contrastive information encoded in lexical entries –Much remains to be understood

Learning Sound Patterns Phonological learning problem –1 year olds know distribution of surface categories –They behave as if they know conditioned allophones because the critical tests involve phonotactic violations –The challenge is to learn relations among surface patterns - implies some notion of phonological similarity, e.g. t-t h are related, or evidence of morphophonological alternations –Challenge: similarity space is not straightforward, e.g., flap is an allophone of /d,t/ in English, but of /r-l/ in Korean. –Surface patterns can be learned without knowing meanings, i.e. without a lexicon; meanings shouldn’t be necessary even for learning conditioned allophony So what is the connection between lexical learning and phonological encoding?

Learning the Lexicon Developmental change in lexical encoding –Prior to ‘vocabulary spurt’ (~50 words), lexical encoding is slow and labored - fine detail only evident in highly familiar words –Later, detailed lexical encoding can be handled much more efficiently Is this related to the learning of a phonological system? –Early difficulties in encoding could be attributed to the lack of an appropriate phonological ‘alphabet’ for the native language –But how can this be reconciled with the surface knowledge of sound patterns in 12-month olds? Do children gradually develop more efficient lexical representations as they accrue knowledge of what is predictable?