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Speech Production1 Articulation and Resonance Vocal tract as resonating body and sound source. Acoustic theory of vowel production

Dec 27, 2015

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  • Articulation and ResonanceVocal tract as resonating body and sound source.Acoustic theory of vowel production.

    Speech Acoustics

  • Basic Anatomy Review

    Speech Acoustics

  • Basic Anatomy Review

    Speech Acoustics

  • Basic Anatomy Review

    Speech Acoustics

  • Vocal tract as resonating body and sound source.

    Phonation sound source is VF vibration.Vocal tract is 1/4 wavelength resonator 17 cm long in the average adult male. Open end is mouth and closed end is vocal folds.There are a number of secondary 1/4 wavelength resonators due to changes in tube diameter.

    Speech Acoustics

  • Speech Acoustics

  • Acoustic (Source) Theory of Vowel ProductionSourceFilter

    Speech Acoustics

  • SourceSource of all vowels is vocal fold vibrationSource creates fo and harmonicsHarmonics are attenuated with an increase in frequency

    Speech Acoustics

  • Speech Acoustics

  • FilterFilters modify the intensity of harmonicsRemember The vocal tract a 17 cm 1/4 WL resonator and has a primary resonant frequency of 500 Hz & secondary resonant frequencies at 1500 and 2500 Hz.Transfer function shows effects of vocal tract resonance.

    Speech Acoustics

  • Insert figure 4.62

    Speech Acoustics

  • Interaction between source and filterIn real world there are additional resonances which interact in vowel production.Every time you change vocal tract configuration you change resonant peaks.You also have radiation effect which results in 6 dB/octave increase in high frequencies.All these factors interact to produce a vowel.

    Speech Acoustics

  • Interaction between source and filter

    Speech Acoustics

  • In above example resonant peaks are labeled F1, F2, & F3. These are known as formant frequencies.Formant frequencies can be displayed on a Spectrogram which shows frequency on ordinate and time on abscissa.

    Speech Acoustics

  • English Speech SoundsVowels & DiphthongsSemivowelsNasalsStopsFricativesAffricatesSound InfluenceSuprasegmentals

    Speech Acoustics

  • VowelsVowels classified by tongue and mandible position.High front vowelsLow back vowelsHigh back vowels

    Speech Acoustics

  • High Front VowelsInclude Tongue placed high and forward in vocal tactMandible somewhat closedHigh oral constriction

    Speech Acoustics

  • Low back vowelsTongue constriction occurring to the rear of vocal tractMandible opening is wide. Pharyngeal constriction is greater than other vowels.

    Speech Acoustics

  • High back vowelsTongue constriction in back of vocal tract.Mandible is somewhat closed.Lips are somewhat protruded.

    Speech Acoustics

  • Vowel Quadrilateral

    Speech Acoustics

  • Vowels may be displayed showing formant frequencies

    Speech Acoustics

  • Spectrograms of Some Vowels

    Speech Acoustics

  • DiphthongsVowels of changing resonance

    On next slide we have examples of diphthongs. Notice how F1 and F2 transitions between first and second vowel.

    Speech Acoustics

  • Speech Acoustics

  • Speech Acoustics

  • Diphthongs (continued)Peterson and Lehiste call shorter diphthongs Tense Monophthongs. These include diphthongs found in bay and boatLonger diphthongs are those found in find, bout, boy

    Speech Acoustics

  • Semivowel productionFour semivowels /w, j, r, l/Similar to vowels because they are highly resonant.Considered to be consonants because they function in language to release the vowel or diphthong. E.g., swim is possible swm is not.

    Speech Acoustics

  • Semivowels (continued)Two classes of semivowelsGlides /j, w/Liquids /l, r/

    Speech Acoustics

  • Semivowels (continued)Glidesare so named because the formants glide to and from adjacent vowels. Very similar to a diphthong except it has a much faster transition.In terms of place of production /j/ is considered a palatal glide/w/ is labial glide

    Speech Acoustics

  • Speech Acoustics

  • Semivowels (continued)LiquidsInvolve placing tongue tip either close to or near the alveolar ridge./r/ - tongue tip does not touch alveolar ridge while airflow passes centrally through a grooved tongue.Some dialects omit /r//w/ for /r/ substitution is common since /w/ is easier to produce.

    Speech Acoustics

  • Semivowels (continued)/l/ - tongue tip touches alveolar ridge while airflow passes laterally. In initial position /l/ is produced as speaker releases the tongue. In the final position it is of long duration. /l/ of long duration are sometimes referred to as a dark /l/

    Speech Acoustics

  • Speech Acoustics

  • NasalsInclude /m/, /n/, and /ng/Anti-resonances need to discuss prior to actual nasal production.Opposite of resonance. Attenuates a range of frequencies.All nasals have anti-resonances which are a result of a cul-de-sac formed by closed vocal tract.

    Speech Acoustics

  • Speech Acoustics

  • Nasals (continued)Place of articulation has a direct effect on size of cul-de-sac and anti-resonant frequency. The place of artic and anti-resonant frequency for each nasal is as follows . . .

    Speech Acoustics

  • Nasals (continued)Other characteristics include All air passes through nasal cavity.Because air passes through nasal cavity (longer pathway than oral tract) you have a lower resonant frequency than non-nasals.Nasals have relatively low intensity, especially for upper formants.

    Speech Acoustics