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

Speech Production 1

Articulation and Resonance

• Vocal tract as resonating body and sound source.

• Acoustic theory of vowel production.

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Basic Anatomy Review

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Basic Anatomy Review

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Basic Anatomy Review

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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.

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Acoustic (Source) Theory of Vowel

Production• Source• Filter

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Source

• Source of all vowels is vocal fold vibration

• Source creates fo and harmonics

• Harmonics are attenuated with an increase in frequency

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Filter

• Filters modify the intensity of harmonics

• Remember… 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.

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• Insert figure 4.62

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Interaction between source and filter

• In 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.

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Interaction between source and filter

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• 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.

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English Speech Sounds

• Vowels & Diphthongs• Semivowels• Nasals• Stops• Fricatives• Affricates• Sound Influence• Suprasegmentals

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Vowels

• Vowels classified by tongue and mandible position.

• High front vowels• Low back vowels• High back vowels

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High Front Vowels

• Include • Tongue placed high and forward in vocal tact

• Mandible somewhat closed• High oral constriction

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Low back vowels

• Tongue constriction occurring to the rear of vocal tract

• Mandible opening is wide. Pharyngeal constriction is greater than other vowels.

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High back vowels

• Tongue 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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Diphthongs

• Vowels of changing resonance

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

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Diphthongs (continued)

• Peterson and Lehiste call shorter diphthongs Tense Monophthongs. These include diphthongs found in “bay and boat”

• Longer diphthongs are those found in “find, bout, boy”

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Semivowel production

• Four 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 semivowels…– Glides /j, w/– Liquids /l, r/

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Semivowels (continued)

• Glides…– are 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

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Semivowels (continued)

• Liquids…– Involve 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.

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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/”

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Nasals

• Include /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.

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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 . . .

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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.