Chapter 4 Phonology in neurolinguistics Phonetics Both study

Chapter 4 Phonology in neurolinguistics

Phonetics Both study speech sounds. Phonetics focuses on sound aspects in terms of their Ë Articulatory movement Distinctive features Ë Acoustic features Ë Perceptual properties Example: the sounds of English and Spanish http: //soundsofspeech. uiowa. edu/english. html

The IPA The sounds: http: //web. uvic. ca/ling/resources/ipa/charts/IPAlab/I PAlab. htm

IPA symbols for English phonemes

Phonetic Feature Encoding in Human Superior Temporal Gyrus

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 aphasia

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

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 AAAS

Fig. 3 Neural encoding of vowels. (A) Formant frequencies, F 1 and F 2, for English vowels (F 2 -F 1, dashed line, first principal component). Nima Mesgarani et al. Science 2014; 343: 1006 -1010 Published by AAAS

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 AAAS

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.

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. Ë addiction Ë actual or action Ë partial Ë prediction

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/. Ë criticize or criticism Ë fanaticism Ë romanticism

Phonology: The syllable S onset h rhyme nucleus e coda l p Sonority: The higher the sonority, the higher the salience.

Phonology: Tone and Intonation Example: Mandarin Chinese and English linguistically significant F 0 (fundamental frequency) contrasts

Characteristics of aphasic speech Common symptoms Ë Ë Phonemic and lexical substitutions (Phonological paraphasias) Use of made-up words (Neologisms) Ë Misuse of grammar

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 → train

More Examples

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 frob Word-finding problem? Motor-programming problem?

Theoretical explanations The cause of paraphasias is phonological. Ë Phonological similarity and contiguity Ë Phonotactic rules Ë 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.