Jonathan Harrington Contextual ambiguities in speech signals and their consequences for sound change

Historical sound change Siþen þe sege and þe assaut watz sesed at Troye, Þe borȝ brittened and brent to brondeȝ and askez, Chaucer, Canterbury Tales, late 14 th C. Sincesiegeassaultceased burgburntashes People often ask me what made me take up writing... You see I put it all down to the fact that I never had any education. Agatha Christie, 1955

Sound change and language-internal factors J. Ohala (1981, 2008) suggests that the conditions for sound change to occur can be met when exceptionally listeners process or parse coarticulation in a way that is different from the way in which it was produced.

Parity in coarticulation In production A nasalised vowel is heard as ORAL in a nasal context like /m_n/: listeners undo or reverse coarticulation in production In perception e.g. Kawasaki, Beddor and others:

Coarticulation and sound change According to Ohala, some change can come about when listeners exceptionally fail to normalise coarticuation – i.e. to normalise for variation in relation to its context. flapThe earth used to be flat but now it's a sphere

Normalisation for context in vision Insufficient normalisation manbad In context Insufficient normalisation Latin: 'manus' > French 'main' = /mã/ (Hand) Associated sound change

Others (e.g. Bybee, Lindblom) see the origin of sound in hypoarticulated speech. This is type of speaking style in which the signal is less clear if the words are either predictable from context and/or less important for understanding what is being said. Hypoarticulated speech

Coarticulation and hypoarticulated speech 1 Perhaps the conditions for sound change are met because the information allowing listeners to process/parse coarticulation is degraded in hypoarticulated speech. To test this in the laboratory, we investigated coarticulation in prosodically accented (analogous to hyperarticulated) and deaccented (hypoarticulated) speech. 1. J. Harrington, F. Kleber, J. Siddins, U. Reubold, Laboratory Phonology (2014)

The first coarticulatory effect to be investigated using German materials is polysyllabic shortening which is sometimes associated with historical sound changes e.g. south (long) but southerner (short). Polysyllabic shortening coarticulation Is the available information to process coarticulation diminished in hypoarticulated speech? Hypoarticulated : MARIA hat sackt verstanden HYPERarticulated : Maria hat SACKT verstanden 26 1 st language German speakers produced the 4 target words in contexts that were typical of HYPER- and hypoarticulated speech (prosodically accented vs. deaccented) sackt /zakt/ sagt /za:kt/ V/C (duration) ratio (‘sags’) (‘says’) sackte /zaktə/ sagte /za:ktə/ (past tense)

SACKT SAGT SACKTE SAGTE log(V/C) 2 syll 1 syll HYPERarticulated short V long V sacktsagt sacktesagte Hypoarticualted short V long V log(V/C) context Coarticulatio n(2 vs. 1 syllable) Production: less coarticulatory information in hypoarticulated speech Is less in hypoarticulated P(long) Gaussian (logistic) classification

We tested whether the same subjects as listeners have more difficulty parsing this kind of coarticulatory information in hypoarticulated speech. To do so, we synthesised continua between sackt-sagt and sackte-sagte such that the target word was accented or deaccented by manipulating only the fundamental frequency (not duration!). The listeners’ task was to label (forced-choice) each stimulus as one of sackt, sagt, sackte, sagte Perception Annahatte SACKT(E)- SAGT(E) verstanden ANNA sackt(e)- sagt(e)

Influence of context (2 vs. 1 syllable) log(V/C) HYPERarticulated Hypoarticulated P(long) Context has a bigger influence on decisions in HYPERarticulated. i.e. listeners are less accurate in parsing coarticulation if they are led to believe that the speech is hypoarticulated Perception (Vertical axis: proportion of long i.e. sagt(e) vs. sackt(e) vowel judgments)

Intermediate summary The conditions for sound change are met when listeners fail to process (parse) coarticulation in a way that is consistent with its production. This mismatch between the modalities of production and perception is especially likely under conditions in which the signal is degraded due to a hypoarticulated speaker style.

Dissimilation: in which a repeated sound is deleted. (e.g. Grassman’s law, Ancient Greek /trik h os/ (‘hair’ genitive) presumably derived from /t h rik h os/ (cf. /t h riks/, ‘hair’ nominative) Sound change and dissimilation 1 Ohala’s model: Listeners incorrectly interpret the first /h/ as due to coarticulation caused by the second/ h/ (i.e. an over-application of context in which coarticulation is incorrectly factored out.) 1. Mary Stevens & Jonathan Harrington, Paper presented at 3 rd sound change workshop, San Francisco

Dissimilation and analogy to vision 1. An over-application of perspective (caused by the room being crooked) causes the illusion that one of the monozygotic twins is bigger than the other

We investigated the basis of /w/ dissimilation as shown by changes such as: /k ɪ nkwe / /kw ɪ nkwe/ /tʃ ɪ iŋkwe/ (cinque) But no /w/ deletion /kw ɪ ndekim/ /kw ɪ nditʃi / Italian (fifteen) Latin Sound change and dissimilation

An 11-step canto-quanto /kanto- kwanto/ continuum (sing, how much) 13 listeners heard this continuum before quattro and sette F2 was also lowered in –anto to simulate lip-rounding Sound change and dissimilation If so, they should hear more canto preceding quattro (because the 2 nd /w/ masks the first /w/ in /kwanto kwatro/) 1. Ohala: a repeated /w/ can make the first /w/ hard to hear because listeners interpret the first /w/ as due to coarticulation 2. (based on results from sackt/sagt). The effect in 1. might disappear when the continuum is deaccented. Predictions detto KWANTO-CANTO The continuum was ACCENTED or deaccented DETTO kwanto-kanto quattro sette volte Ho×

_ quattro _ sette quanto canto /kw/ /w/ Sound change and dissimilation response acoustics The word effect disappears for deaccented (consistent with 2) deaccented accented More quanto responses before _quattro for accented (contra 1)Results 3. More canto responses when deaccented Predictions 1. More canto responses in a quattro context (Ohala) 2. The influence of coarticulation is less in deaccented (Harrington)

Link to sound change The identification of the first /kw/ in Latin quinque depended on lip-rounding spread through the word which listeners had difficulty hearing, when quinque was hypoarticulated (leading to a perception of /kinkwe/). Dissimilation No evidence from these results for Ohala’s idea that dissimilation comes about through perceptual masking Instead: An initial /kw/ benefits from a final /kw/ (of quattro) but only in accented words In deaccented (hypoarticulated) words, this effect disappears and there is a bias towards canto i.e. the conditions for sound change are met in hypoarticulated speech because in this speaking style, processing coarticulation is more difficult for listeners. Summary

Sound change and external factors Sound change could also come about because speakers do not process coarticulation in the same way. 1 st language listeners – who vary in the extent of coarticulation in production and its normalisation in perception (Beddor, 2009; Baker et al, 2011). Different speaker groups: e.g. Yu (2013) has shown that normalising for coarticulation is influenced by personality traits such as autism. Dialects/languages have different degrees of coarticulation.

Sound change and external factors: adults and children Sound change may also come about because children normalise less effectively for coarticulation than adults. Some evidence again from vision e.g. In contrast to most adults, children under 7 years tend to perceive (correctly) that the circle on the right is larger than the one of the left Doherty et al, 2010, Developmental Science: Young children are less accurate than adults when context is helpful, but more accurate when context is misleading

The general hypothesis to be tested is that for children vs. adults: 1. The magnitude of coarticulation in production may be similar (or greater) 2. Children’s ability to normalise for coarticulation may be less If 2, then their relative inability to normalise for context may be a source of sound change. Coarticulation: adults and children 1 1. Felicitas Kleber & Sandra Peters, Presented at Laboratory Phonology, Japan, 2014.

Children and coarticulation: present study Materials /ʊ, ʏ/ are contrastive in German (musste/müsste: ‘had to’/ ‘should’) and are acoustically differentiated primarily by a lower/higher second formant frequency. Nonwords: /pʊp, pʏp, tʊt, tʏt/ Subjects 13 L1-German pre-school children aged between 5-6 years. 20 L1-German adults. Labialisation in /p_p/ shifts /ʏ/ towards /ʊ/ Tongue-tip contact in /t_t/ shifts /ʊ/ towards /ʏ/ Coarticulation

Tutt Tütt Pupp Püpp Pictures of real words (e.g. ski, shoe) and of characters whose names were /tʊt/, /tʏt/, /pʊp/, and /pʏp/ 2 vowels × 2 contexts × 5 repetitions × 13 children = 260 tokens 2 vowels × 2 contexts × 20 repetitions × 20 adults = 1600 tokens Production Children Adults

Quantifying coarticulation We obtained a relative measure separately per speaker of the distance, d, of any vowel (V) to the means of /ʊ, ʏ/ in /pʊp, tʏt/ (in which consonant acoustics reinforce the /ʊ, ʏ/ separation) in an F1 × F2 space (formant values extracted at the vowels’ temporal midpoints). pʊppʊp tʏttʏt V d = log(dʊ/dʏ) d is negative: closer to pʊp d is positive: closer to tʏt d is zero: equidistant between the two F1 F2 dʊ dʏ

Quantifying coarticulation Nearer tʏt Nearer pʊp d 0 high Coarticulation in pʏp low Coarticulation in tʊt high

Results: coarticulation in production 1. More coarticulation in /tʊt/ than in /pʏp/ 2. No differences in the magnitude of coarticulation between adults and children. (The nearer tʊt, pʏp are to d = 0, the greater the coarticulation) AdultChild AdultChild

Perception (method) We synthesised an 11-step /ʊ-ʏ/ continuum and embedded it in /p_p/ and /t_t/ contexts. Adults: forced choiced perception test: identification of each stimulus as one of PUPP, PÜPP, TUTT, TÜTT Children: an imitation task – they produced one of the above four ‘names’ in response to each stimulus. Maria hat CVC gesagt × 13 children = 858 tokens × 20 adults= 1320 tokens 2 continua × 11 stimuli × 3 repetitions

Perception (method): imitations and categorical response In order to compare with adult categorisations, we classified each child’s imitation as /ʊ/ or /ʏ/ after (Gaussian) training on the same child’s speech production tokens (separately by consonantal context). X Ʊ ʏ e.g. X = child’s imitation of a stimulus from the perceptual p_p continuum /ʊ, ʏ/ are distributions of productions by the same child in the same p_p context in a formant space. X is categorised as /Y/

Some predictions 1. (Trivially) Listeners normalise for coarticulation in relation to how it is produced i.e. more /ʊ/ perceived in t_t than in p_p pʊp pʏp Production Distance ratio tʊt tʏt Perceived as ʏ ʊ 2. Perceptual normalisation: less for children?

AdultsChildren Results: less perceptual normalisation for context by children Acoustic synthetic stimulus /ʊ/-like / ʏ /-like ʏ Ʊ Perceived as p_pt_t

Conclusions Sound change can occur when listeners misinterpret how phonological contrasts are associated with articulatory information that is temporally distributed in the speech signal. This misinterpretation is especially likely in a hypoarticulated speaking style in which (a) the coarticulatory information may be less saliently communicated by the speaker and/or (b) listeners’capacity for processing coarticulation is diminished. Developmental factors may be relevant – in particular if children’s ability to resolve coarticulation as listeners is weak in relation to the magnitude of coarticulation in their own speech production.