The Articulation and Acoustics of Consonants

Speech ScienceFall 2009

Nov 2, 2009

OutlineSuprasegmental features of speech

StressIntonationDuration and Juncture

Role of feedback in speech productionAuditory feedbackTactile feedbackProprioceptive feedbackInternal feedback

The effects of context on the production of speech soundsThe speech sounds occur in context and are

affected and altered by neighboring sounds.

1) Assimilation2) Coarticulation

AssimilationA linguistic process by which a sound

becomes similar to an adjacent soundSimply put, the articulator takes a shortcut

E.g., Eat the cakeThe fricative sound has influenced its neighbor,

/t/, so that the /t/ becomes more like / /, in its articulation.

CoarticulationTwo 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 consonantsWhen producing the word “stoop” , lip

rounding gesture for [u] may begin during the production of initial [s].

SuprasegmentalsThe suprasegmental or prosodic features of

speech are overlaid on syllables, words, phrases, and sentences.StressIntonationDuration and Juncture

StressSyllables – binding of consonants and vowelsSyllable is the unit of stressLexical 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 importantWHICH 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 verbsE.g., PERmit versus perMIT

StressThe more stress – the more effortThe three acoustic characteristics that are

most often associated with heavily stressed syllables are1) higher f0

2) greater duration3) greater intensity than weakly stressed

syllables

IntonationIntonation is variation of pitch while speakingIntonation patterns (perceived changes in f0)

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 agoHow do you like it here?

IntonationAnother 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 JunctureSpeech sounds vary in intrinsic duration.Fricatives, nasals and semivowels have

longer durations than stop consonantsVowels 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 JunctureJuncture: 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 ControlHow 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 productionRole 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 productionClosed 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 productionAuditory feedback

DAF effectAuditory

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 productionTactile feedback

Sense of touchLight touch, perception of deep pressureAnesthetizing various nerve branches of

trigeminal nerve – distortion of /s/In general, speech remain highly intelligible

Role of feedback in speech productionProprioceptive feedback

Direct feedback from musclesIt is delivered more quicklyIt allows us to sense the velocity and direction

of movement and position of body structuresSensors in joints that transmit information

about bone anglesReceptors along tendons that respond to

muscle contractions and transmit data about muscle stretching and shortening.

Role of feedback in speech productionInternal 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 productionThe 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.