Sound 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)

Joseph Fourier ( ) Time --> Frequency Amplitude Any function can be decomposed in terms of sinusoidal (= sine wave) functions (‘basis functions’) of different frequencies that can be recombined to obtain the original function. [Wikipedia entry on Fourier Analysis]

Frequency - Male Vowels

Frequency - Female Vowels

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

Schedule Lab #1A – Classic speech perception tasks –individual data: collect by Weds Sept 10th –due Monday Sept 21st Lab #1B - New speech perception tasks –Task 1: rapid sequence recall (Dupoux et al. 2008) –Task 2: implicit discrimination (Navarra et al. 2005) –collect individual data by Thursday Sept 24 th – to –group data files available shortly thereafter – team analysis welcome/encouraged –due Friday Oct 2nd

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

Kazanina et al., 2006 Proceedings of the National Academy of Sciences, 103,

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

Quantifying Sensitivity

Response bias Two measures of discrimination –Accuracy: how often is the judge correct? –Sensitivity: how well does the judge distinguish the categories? Quantifying sensitivity –HitsMisses False AlarmsCorrect Rejections –Compare p(H) against p(FA)

Quantifying Sensitivity Is one of these more impressive? Harder to obtain by chance? –p(H) = 0.75, p(FA) = 0.25 –p(H) = 0.99, p(FA) = 0.49 A measure that amplifies small percentage differences at extremes z-scores

Normal Distribution Mean (µ) Dispersion around mean Standard Deviation A measure of dispersion around the mean. √( ) ∑(x - µ) 2 n Carl Friederich Gauss ( )

The Empirical Rule 1 s.d. from mean: 68% of data 2 s.d. from mean: 95% of data 3 s.d. from mean: 99.7% of data

Normal Distribution Mean (µ) 65.5 inches Standard deviation  = 2.5 inches Heights of American Females, aged 18-24

Quantifying Sensitivity A z-score is a reexpression of a data point in units of standard deviations. (Sometimes also known as standard score) In z-score data, µ = 0,  = 1 Sensitivity score d’ = z(H) - z(FA)

See Excel worksheet sensitivity.xls

Quantifying Differences

(Näätänen et al. 1997) (Aoshima et al. 2004) (Maye et al. 2002)

Normal Distribution Mean (µ) Dispersion around mean Standard Deviation A measure of dispersion around the mean. √( ) ∑(x - µ) 2 n

The Empirical Rule 1 s.d. from mean: 68% of data 2 s.d. from mean: 95% of data 3 s.d. from mean: 99.7% of data

If we observe 1 individual, how likely is it that his score is at least 2 s.d. from the mean? Put differently, if we observe somebody whose score is 2 s.d. or more from the population mean, how likely is it that the person is drawn from that population?

If we observe 2 people, how likely is it that they both fall 2 s.d. or more from the mean? …and if we observe 10 people, how likely is it that their mean score is 2 s.d. from the group mean? If we do find such a group, they’re probably from a different population

Standard Error is the Standard Deviation of sample means.

If we observe a group whose mean differs from the population mean by 2 s.e., how likely is it that this group was drawn from the same population?

Development of Speech Perception in Infancy

Voice Onset Time (VOT) 60 msec

Perceiving VOT ‘Categorical Perception’

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

Abstraction Representations –Sound encodings - clearly non-symbolic, but otherwise unclear –Phonetic categories –Memorized symbols: /k/ /æ/ /t/ Behaviors –Successful discrimination –Unsuccessful discrimination –‘Step-like’ identification functions –Grouping different sounds

Let’s Learn Inuktitut! Video: Nunavik: Building on the Knowledge of Ancestors

Vowels Consonants

Three 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

high amplitude sucking non-nutritive sucking

English VOT Perception To Test 2-month olds 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 [these findings based mostly on looking/headturn studies w/ 6 month olds]

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! PK Kuhl & JD Miller, Science, 190, (1975)

Joan Sinnott, U. of S. Alabama More recent findings… 1.Auditory perceptual abilities in macaque monkeys and humans differ in various ways 2.Discrimination sensitivity for b-p continua is more fine-grained in (adult) humans (Sinnott & Adams, JASA, 1987) 3.Sensitivity to cues to r-l distinctions is different, although trading relations are observed in humans and macaques alike (Sinnott & Brown, JASA, 1997) 4.Some differences in vowel sensitivity… Suitability of Animal Models

#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?

Korean has [l] & [r] [rupi] “ruby” [kiri] “road” [saram] “person” [irumi] “name” [ratio] “radio” [mul] “water” [pal] “big” [s\ul] “Seoul” [ilkop] “seven” [ipalsa] “barber”

#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’

PRETEST

HABITUATION TEST SAMESWITCH

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,

Werker et al months17 months20 months

Swingley & Aslin, month olds did recognize mispronunciations of familiar words Dan Swingley, UPenn

Alternatives to Reviving Jakobson Word-learning is very hard for younger children, so detail is initially missed when they first learn words Many exposures are needed to learn detailed word forms at early stages of word-learning Success on the Werker/Stager task seems to be related to the vocabulary spurt, rapid growth in vocabulary after ~50 words

So how do infants learn…? Some possibilities: ‘Use it or lose it’ – they stop paying attention to contrasts that they don’t need for the ambient language Minimal pairs (e.g., rock vs. lock) – requires word meanings Acoustic distributions of sounds, requires no word knowledge Seeking contextually conditioned variation, e.g., Korean r/l contrast

(Dietrich, Swingley, & Werker 2007)

Exp 1: tam - ta:m Exp 2: tæm - tæ:m Exp 3: ta/æm - tem Length factor ~

(Dietrich, Swingley, & Werker 2007)

Slides: Swingley 2006, ICIS

[2003, Proceedings of the National Academy of Sciences] 5 hours’ exposure to Mandarin ± human interaction

fricativeaffricate Alveo-palatals

Jessica Maye, Northwestern U.

Infants at age 6-8 months are still ‘universal listeners’, cf. Pegg & Werker (1997) Infants trained on bi-modal distribution show ‘novelty preference’ for test sequence with fully alternating sequence How could the proposal scale up?

p(a) = p(b) p(a) = 2 x p(b)

Slides: Swingley 2006, ICIS

Fenson et al. 2000

bird dog duck doll bread candy head dish radio outside feed today dark toast hat ants tooth table television blanket outside plant wait today fast hurt soft out stroller kitty water babysitter pretty patty cake bottle kitchen don’t night (night) MacArthur Short CDI - 89 items

Fei Xu, Berkeley

Xu & Carey mo.: no surprise 12 mo.: surprise --> “10 month olds do not represent basic sortal/kind concepts” Xu 2002 Add words! 9 mo.:

Fulkerson & Waxman months6 months Words µ =.59, p =.007µ =.63, p <.001 Tonesµ =.53, p =.2µ =.54, p =.2

Yeung & Werker 2009 Effect of Type (±alternating) Exp1: F(1,18) = 5.74, p <.05 Exp2: F(1,18) = 0.53, p =.47 Naturally produced Hindi syllables Dental vs. retroflex A.Familiarize sound-object links B.Test sound discrimination only Exp1: consistent links Exp2: inconsistent links

(Feldman, Griffiths, & Morgan, 2009)

“Simulations demonstrate that using information from segmented words to constrain phonetic category acquisition allows more robust category learning from fewer data points, due to the inter- active learner’s ability to use information about which words contain particular speech sounds to disambiguate overlapping categories.” (Feldman et al. 2009)

Questions Combining words and sound distributions: what do learners need to know? Too-many-colors problem: how to combine across words? Why does interaction matter (Kuhl et al on Mandarin)? What does this predict about 1-year olds’ knowledge of phonological contrast? What changes between 12 & 18 months?

(Jusczyk 1997) Invariance

Training on [g-k] or [d-t], generalization across place of articulation. (Dis-)habituation paradigm. [Maye & Weiss, 2003]

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

Abstraction in Infant Speech Encoding From a very early age infants show great sensitivity to speech sounds, possibly already with some ‘category-like’ structure Although native-like sensitivity develops early (< 1 year), this should be distinguished from adult-like knowledge of the sound system of the language –Children still need to learn how to efficiently encode words (phoneme inventory) –Children presumably still need to learn how to map stored word forms onto pronunciations (phonological system of the language) Popular distributional approaches to learning the sound system address rather non-abstract encodings of sounds, at best

More Issues… Is there distributional evidence for contrasts in the input? –Maye et al.: children can learn –Werker et al.: demonstration from Japanese/English maternal speech –How well does this scale beyond duration (1-dimensional)? Child needs to store all exemplars Child needs to know all relevant dimensions –This could yield at most phones, not phonemes Why do children fail on minimal pair learning? –Inaccurate representations, qualitatively different representations –Hard tasks –Fennell et al.: context helps

Questions about Development Change from 6-12 months –What changes? Structure changing vs. structure adding –What causes change to occur? Statistical distributions of sounds –Reliably separable distributions? –Storing and organizing tokens for analysis –Knowing appropriate acoustic dimensions –Allophony, e.g., k-palatalization in English Why does it take so long? Change from months –What changes? –(Skepticism about the effect) –What causes change to occur?

6-12 Months: What Changes? (clunky diagram, from Phillips, 2001)

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 [cf. Phillips 2001, Cogn. Sci., 25, ]