Speech Production1 Articulation and Resonance Vocal tract as resonating body and sound source. Acoustic theory of vowel production
Dec 27, 2015
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
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Low back vowelsTongue constriction occurring to the rear of vocal tractMandible opening is wide. Pharyngeal constriction is greater than other vowels.
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High back vowelsTongue constriction in back of vocal tract.Mandible is somewhat closed.Lips are somewhat protruded.
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Vowel Quadrilateral
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Vowels may be displayed showing formant frequencies
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Spectrograms of Some Vowels
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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.
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Semivowels (continued)Two classes of semivowelsGlides /j, w/Liquids /l, r/
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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
