Speech Science Fall 2009 Nov 2, 2009

Outline Suprasegmental features of speech Stress Intonation Duration and Juncture Role of feedback in speech production Auditory feedback Tactile feedback Proprioceptive feedback Internal feedback

The effects of context on the production of speech sounds The speech sounds occur in context and are affected and altered by neighboring sounds. 1) Assimilation 2) Coarticulation

Assimilation A linguistic process by which a sound becomes similar to an adjacent sound Simply put, the articulator takes a shortcut E.g., Eat the cake The fricative sound has influenced its neighbor, /t/, so that the /t/ becomes more like / /, in its articulation.

Coarticulation Two articulators are moving at the same time for different phonemes. E.g., two, speaker rounds the lips for [u] at the same time that the tongue is active for [t]. Temporal overlap between the articulatory gestures for the vowels and consonants When producing the word “stoop”, lip rounding gesture for [u] may begin during the production of initial [s].

Suprasegmentals The suprasegmental or prosodic features of speech are overlaid on syllables, words, phrases, and sentences. Stress Intonation Duration and Juncture

Stress Syllables – binding of consonants and vowels Syllable is the unit of stress Lexical stress: the pattern of stress within words Bat, eat, and tea are monosyllables Beyond, hidden, and table are disyllables Unicorn, immediate are polysyllables.

Stress Stress indicates which information in an utterance is most important WHICH one of those green books is yours? That’s NOT green book! WHOSE green book is this? IS that your RED book? Lexical stress differentiates nouns and verbs E.g., PERmit versus perMIT

Stress The more stress – the more effort The three acoustic characteristics that are most often associated with heavily stressed syllables are 1) higher f 0 2) greater duration 3) greater intensity than weakly stressed syllables

Intonation Intonation is variation of pitch while speaking Intonation patterns (perceived changes in f 0 ) can be imposed on a sentence, a phrase, or even a word. Sentences typically have rise-fall intonation curve. Pitch rises during the first part and falls at the end. He left an hour ago How do you like it here?

Intonation Another intonation pattern is the end-of-utterance pitch rise. Pitch rise indicates question to be answered with yes or no. Is it Ready? As I think about it…..

Duration and Juncture Speech sounds vary in intrinsic duration. Fricatives, nasals and semivowels have longer durations than stop consonants Vowels have greater duration when they occur before voiced consonants (e.g., leave versus leaf) They are also longer before continuants (e.g., leave versus leap)

Duration and Juncture Juncture: the way sounds are joined to (or separated from) each other. E.g., [an aim] versus [a name] Affiliation of [n] is determined by differences in duration combined with other sound changes.

Speech Motor Control How do speaker control production of speech? To what degree does the speaker monitor his/her actions? The production of speech requires the simultaneous and coordinated use of respiratory, phonatory, and articulatory mechanisms.

Role of feedback in speech production Four kinds of information are available to a speaker that could be used in feedback control. Auditory feedback Tactile feedback Proprioceptive feedback Internal feedback

Role of feedback in speech production Closed loop systems versus open –loop systems Closed loop systems: the performance of the system is fed back to be matched with the program If there is a discrepancy between the program and the performance, adjustments are made to bring the performance in line with the program. In open loop systems, the output is preprogrammed and does not require feedback

Role of feedback in speech production Auditory feedback DAF effect Auditory information may not serve effectively as a feedback mechanism to monitor ongoing, skilled articulation. The information it provides to the speaker arrives too late.

Role of feedback in speech production Tactile feedback Sense of touch Light touch, perception of deep pressure Anesthetizing various nerve branches of trigeminal nerve – distortion of /s/ In general, speech remain highly intelligible

Role of feedback in speech production Proprioceptive feedback Direct feedback from muscles It is delivered more quickly It allows us to sense the velocity and direction of movement and position of body structures Sensors in joints that transmit information about bone angles Receptors along tendons that respond to muscle contractions and transmit data about muscle stretching and shortening.

Role of feedback in speech production Internal feedback It is the conveyance of information within the brain about motor commands before motor response itself. Feedback of this type is possible because in addition to information fed back from periphery, the nervous system can convey information in loops that are central, entirely within the brain.

Role of feedback in speech production The more central the system, the earlier it can feed back information and more effective it can be for ongoing control of rapid and complex motor patterns. The more peripheral systems, operating after the motor response, can be effective for comparing result with intension and may therefore be important for learning new motor pattern.