Chapter 4 Phonology in neurolinguistics - PowerPoint Presentation

Slide1

Chapter 4

Phonology in

neurolinguisticsSlide2

Phonetics

Both study speech sounds.

Phonetics focuses on sound aspects in terms of their

Articulatory movement

Distinctive features

Acoustic features

Perceptual properties

Example: the sounds of English and Spanish

http://

soundsofspeech.uiowa.edu/english/english.html

Slide3

The IPA

The

sounds:

http://web.uvic.ca/ling/resources/ipa/charts/IPAlab/IPAlab.htmSlide4

IPA symbols for English phonemesSlide5

Phonetic Feature Encoding in Human Superior Temporal GyrusSlide6

Mesgarani

et al. (2014) recorded direct cortical activity from six participants while they listened to natural speech samples containing 500 English sentences spoken by 400 different people.

They

found that electrodes were sensitive to the distinctive features that make phonemes. P

honemic

sensitivity is organized primarily by manner, and secondarily by place of articulation, thus converging with the hierarchy of distinctive features put forth by Roman

Jakobson

in the early forties, to explain the acquisition of phonemes in children and their loss in aphasiaSlide7

For example, one electrode showed large evoked responses to phonemes /p/, /t/, /k/, /b/, /d/ and /g/; these phonemes are stop

s

, they all involve a block in the vocal tract that ceases

airflow

. Another electrode was sensitive to sibilants (/s/, /ʃ/, /z/), made by directing a stream of air with the tongue towards the sharp edge of the

teeth

, which are held close together. Importantly, most electrodes are selective to classes of phonemes that share a feature, not to individual phonemes. Among the electrodes that evoked a response to stops, some were responsive to all stops, but others were selective to the place in the vocal tract where the block of airflow happens: at the back of the mouth (/g/, /k/), in the middle (/d/, /t/), or with the lips (/p/, /b/). Slide8

Fig. 1 Human STG cortical selectivity to speech sounds.(A) Magnetic resonance image surface reconstruction of one participant’s cerebrum.

Nima Mesgarani et al. Science 2014;343:1006-1010

Published by AAASSlide9

Fig. 3 Neural encoding of vowels.(A) Formant frequencies, F1 and F2, for English vowels (F2-F1, dashed line, first principal component).

Nima Mesgarani et al. Science 2014;343:1006-1010

Published by AAASSlide10

Fig. 4 Neural encoding of plosive and fricative phonemes.(A) Prediction accuracy of plosive and fricative acoustic parameters from neural population responses.

Nima Mesgarani et al. Science 2014;343:1006-1010

Published by AAASSlide11

Representation of speech in human auditory cortex: is it special?

The fundamental frequency of male speakers is represented by more rapid neural activity phase-locked to the glottal pulsation rate in both humans and monkeys. In both species, the differential representation of stop consonants varying in their POA can be predicted by the relationship between the frequency selectivity of neurons and the onset spectra of the speech sounds. These findings indicate that the neurophysiology of primary auditory cortex is similar in monkeys and humans despite their vastly different experience with human speech, and that

Heschl's

gyrus is engaged in general auditory, and not language-specific, processing.Slide12

Phonology

Phonology focuses on sound patterns and combinatory rules or constraints

Example 1: PALATALIZATION in English

When

a word that ends with a /t/ is followed by a –

ual

, -

ial

, or -ion ending, the palatal vowel

changes

the /t/ sound into a

fricative

sound

.addict  addictionact  actual or actionpart  partial predict  predictionSlide13

Phonology Example 2:

STOPS

BECOMES CONTINUANTS

Because /k/ is a stop, and vowels are continuants, an affix beginning with a vowel often changes /k/ to /s

/.

critic

 criticize or criticism

fanatic  fanaticism

romantic  romanticismSlide14

S

onset

rhyme

nucleus

coda

h e

l p

Phonology: The

syllable

Sonority: The higher the sonority, the higher the salience.Slide15

Phonology: Tone and Intonation

Example: Mandarin Chinese and English

linguistically significant F0 (fundamental frequency) contrastsSlide16

Characteristics of aphasic speech

Common symptoms

Phonemic and lexical substitutions (Phonological

paraphasias

)

Use of made-up words

(Neologisms)

Misuse of grammarSlide17

Examples of

paraphasia

Phoneme

paraphasia

:

• addition:

butcher →

butchler

• deletion:

butcher →

buter

• substitution:

butcher →

betcher

Word paraphasia:• form-based: butcher → bitch• meaning-based: butcher → grocer• unrelated: butcher → trainSlide18

More Examples Slide19

Examples of

Neologisms

cat → dog (semantic word

paraphasia

) →

rog

(phoneme

paraphasia

)

Example: Utterance by a person with Wernicke’s aphasia/jargon aphasia containing many neologisms:

a frog frock

frossy

that is fro that is

frabbing

is fog is frobWord-finding problem?Motor-programming problem?Slide20

Theoretical explanations

The cause of

paraphasias

is phonological.

Phonological similarity and contiguity

Phonotactic

rules

Similar errors occur in writing and speech

There are clear differences between

paraphasias

in aphasia and ordinary speech errors. In aphasia, there were more paradigmatic errors and less awareness of one’s own errors.