CS 551/651: Structure of Spoken Language

Lecture 4: Characteristics of Manner of Articulation

John-Paul Hosom Fall 2008

Self-Study

If you want to look at spectrograms of your own voice, there are several programs available:

1. Matlab

Use the “specgram” command; color map can be changed using “colormap gray” or similar commands

2. CSLU Toolkit

Download from http://www.cslu.ogi.edu/toolkit Registration required but free for educational use Plot spectrograms with “SpeechView” tool.

3. Praat

Download from http://www.fon.hum.uva.nl/praat/ Free and available for windows, lunix, Macintosh, etc.

Two Vowels: “preempt”

Two Vowels: “heavy oak”

Two Vowels: “reapply”

Acoustic-Phonetic Features: Manner of Articulation

Approximately 8 manners of articulation: Name Vowel Approximant Nasal Plosive Fricative Affricate Aspiration Flap Sub-Types vowel, diphthong liquid, glide unvoiced, voiced unvoiced, voiced unvoiced, voiced Examples . aa, iy, uw, eh, ow, … l, r, w, y m, n, ng p, t, k, b, d, g f, th, s, sh, v, dh, z, zh ch, jh h dx, nx Change in manner of articulation usually abrupt and visible; manner provides much information about location of phonemes.

Acoustic-Phonetic Features: Manner of Articulation

Approximants (/l/, /r/, /w/, /y/): • vowel-like properties, but more constriction • /l/ has tongue-tip touching alveolar ridge, /r/ has tongue tip curled up/back (retroflex), raised and “bunched” dorsum, sides of tongue touching molars, /w/ has tongue back and lips rounded, /y/ has tongue toward front and very high • glides (/w/, /y/) can be viewed as “extreme” production of a vowel (sometimes called semivowels): /w/  /uw/ /y/  /iy/ 7

Acoustic-Phonetic Features: Manner of Articulation

Approximants (/l/, /r/, /w/, /y/): • movement of tongue slower than other vowel-to-vowel or consonant-to-vowel transitions, but not as slow as diphthong movement • sometimes voiceless when following a voiceless plosive (“play”) • /l/ may have slight discontinuity when tongue makes/breaks contact with alveolar ridge; other approximants have no discontinuity 8

Acoustic-Phonetic Features: Manner of Articulation

Nasal (/m/, /n/, /ng/): • produced with velic port open and obstruction in vocal tract • sound travels through nasal cavities • these cavities filter speech with both poles (resonances) and zeros (anti-resonances) • longer pathway causes primary resonance to be low (220-300 Hz) • anti-resonances cause higher frequencies to have lower power F1 P1 F2 F3 P2 F4 F5 F6 /m/ Z1 9 Z2

Acoustic-Phonetic Features: Manner of Articulation

Nasal (/m/, /n/, /ng/): • formant structure obscured by pole-zero pairs • all three English nasals look and sound similar (place of articulation has little effect on spectrum); can be distinguished primarily by coarticulatory effects on adjacent vowel(s).

• sometimes very brief duration (“camp”, “winner”) • occasional confusion with /w/, /l/ (if F3 not visible), and closure portion of voiced plosives • often sharp discontinuity with adjacent vowel • adjacent vowel may be nasalized 10

Acoustic-Phonetic Features: Manner of Articulation

Plosive (Oral Stop) (/p/, /t/, /k/, /b/, /d/, /g/): 1. closure along vocal tract (lips, alveolar ridge, velum) 2. buildup of air pressure behind closure 3. release of closure 4. burst of air 5. possible aspiration following burst • • • • complex process, several changes over brief time span some context-dependent attributes, some semi-invariant ones voiced bursts sometimes have “voice bar” in low frequency region, caused by vocal fold vibration with complete oral and velic closure.

sometimes voice bar is excellent cue; sometimes can be confused with a nasal 11

Acoustic-Phonetic Features: Manner of Articulation

/p ah p/ /t ah t/ /k ah k/ 12

Acoustic-Phonetic Features: Manner of Articulation

Plosive (Oral Stop) (/p/, /t/, /k/, /b/, /d/, /g/): • closure and time required to build pressure results in “silence” region of spectrum prior to burst • burst airflow is a step function, which becomes similar to an impulse, which has equal energy at all frequencies • identity of a plosive contained in (at least) three areas: (1) voice-onset-time (VOT) / duration of aspiration (2) formant transitions in neighboring vowels/approximants (3) spectral shape of burst • “voiced” plosives may not show any real voicing (!) 13

Acoustic-Phonetic Features: Manner of Articulation

Fricative (/f/, /th/, /s/, /sh/, /v/, /dh/, /z/, /zh/): • fricatives produced by forcing air through a constriction in the mouth • constriction located anywhere from the labiodental region (/f/, /v/) to palato-alveolar region (/sh/, /zh/) • all English fricatives come in voiced and unvoiced varieties • voicing may not be present in voiced fricatives (!), making duration an important distinguishing cue (voiced  shorter) • the location and type of the constriction create spectral anti-resonances as well as resonances • the main difference between /s/ and /f/ is in frequencies above 4000 Hz; telephone-band speech has limit of 4KHz.

Acoustic-Phonetic Features: Manner of Articulation

Fricative (/f/, /th/, /s/, /sh/, /v/, /dh/, /z/, /zh/): Rules for distinguishing between /dh/ and /v/: /dh/ formant structure is clearly visible

frication is stronger at 5000 Hz and not so strong at low frequencies /v/ - formants

not

visible at location of maximum frication

low-frequency energy is as strong as the energy at 5000 Hz However, due to the difficulty of distinguishing /dh/ from /v/ and distinguishing /th/ from /f/, in the spectrogram reading exercises we will treat them as the same.

Acoustic-Phonetic Features: Manner of Articulation

Affricate (/ch/, /jh/): • Affricates are conceptually like diphthongs: two separate phonemes considered as one • English has two affricates: /ch/  /t sh/ /jh/  /d zh/ • Sometimes cue to affricate is in burst preceding fricative; in closure between vowel and fricative.

• Sometimes cue to affricate is in voicing or duration.

Acoustic-Phonetic Features: Manner of Articulation

Aspiration (/h/): • like vowels, except usually no voicing • can usually see formant structure • formant patterns similar to surrounding vowel(s)

Acoustic-Phonetic Features: Manner of Articulation

Flaps (/dx/, /nx/): • allophone of /t/, /d/, or /n/ • very brief duration; no closure for /dx/ • indicated by dip in energy and F2 near 1800 Hz “write another” 18

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