Phonetics Janice Fon Graduate Institute of Linguistics National Taiwan University

Phonetics

Janice Fon

Graduate Institute of Linguistics

National Taiwan University

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Overview

Speech sounds and phonetic transcription

Articulatory phonetics

Phonological categories and pronunciation variation

Acoustic phonetics and signals

Phonetic resources

Advanced: articulatory and gestural phonology

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Speech sounds and phonetic transcription (1)

PhoneticsThe study of speech sounds used in the languages of the world

PhoneA speech sound Represented with phonetic symbolsTwo types:

ConsonantsVowels

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Phonetic alphabetsIPA

Standard developed by International Phonetic Association

Alphabet + principles of transcription

ARPAbetDesigned for American English in ASCII symbols

Computer-friendly

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[ɹ]

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Articulatory phonetics (1)

Definition:The study of how phones are produced

The vocal organ

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Sounds are formed by the motion of air through the mouth

Consonants:Made by restricting or blocking the airflow in some way

May be voiced or voiceless

Vowels:Made with less obstruction

Usually voiced

Generally louder and longer than consonants

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Consonants are defined by Place of articulation

The point of maximum constriction

Manner of articulationHow the restriction of airflow is made

Voicing State of the glottis

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Place of articulation

coronal

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LabialSounds whose main restriction is formed at the lips

Two subtypes:Bilabial: two lips

Labiodental: upper teeth + lower lip

Examples [國 ]: [p] 爸 , [pʰ] 怕 , [m] 媽 , [f] 法[閩 ]: [b] 肉 , [p] 爸 , [pʰ] 打 , [m] 媽[E]: [p] spy, [pʰ] pie, [m] my, [f] four, [v] very

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DentalSounds made by placing the tongue against the teeth

Two subtypes:Dental: behind the teeth

Interdental: between the teeth

Examples [國 ]: [t ̪] 大 , [t ̪ʰ] 踏 , [s ̪] 撒 , [t ̪s ̪] 資 , [t ̪s ̪ʰ] 刺 , [n ̪] 那 , [l ̪] 辣 [閩 ]: [t ̪] 大 , [t ̪ʰ] 拖 , [s ̪] 沙 , [z ̪] 熱 , [t ̪s ̪] 十 , [t ̪s ̪ʰ] 柴 , [n ̪] 藍 , [l ̪] 賴 , [ɾ̪] 賊仔[E]: [θ] thing, [ð] the

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AlveolarSounds made by placing the tongue against the alveolar ridge

Two subtypes:Alveolar: b/t teeth and alveolar ridge

Postalveolar/palato-alveolar: after the alveolar ridge

Examples [E]: [t] ten, [d] duck, [n] new, [s] sing, [z] zoo, [l] love, [ɹ] red, [ɾ] butter, [ʃ] she, [ʒ] garage, [tʃ] China, [dʒ] joy

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PalatalSounds made by placing the tongue against the (hard) palate

Two subtypes:Prepalatal/alveolopalatal: the arc towards the roof of the mouth

Palatal: the roof of the mouth

Examples [國 ]: [ɕ] 削 , [tɕ] 交 , [tɕʰ] 敲 , [j] 妖[閩 ]: [ɕ] 是 , [tɕ] 摺 , [tɕʰ] 試 , [ʑ] 皺 , [j] 妖[E]: [j] yes

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Velar Sounds made by placing the tongue against the velum/soft palate

Examples [國 ]: [k] 該 , [kʰ] 開 , [x] 害 , [ŋ] 忙[閩 ]: [k] 該 , [kʰ] 開 , [g] 牛 , [ŋ] 黃[E]: [k] ski, [kʰ] key, [g] good, [ŋ] sing

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Glottal Sounds made at the glottis

Examples [國 ]: [ʔ] 唉[閩 ]: [h] 海 , [ʔ] 食[E]: [h] high, [ʔ] uh-oh

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Retroflex Sounds made with the tongue tip curled back

Examples [國 ]: [ʂ] 扇 , [tʂ] 詹 , [tʂʰ] 蟬 , [ʐ] 然

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Manner of articulationStop

Nasal

Fricative

Affricates

Approximant

Flap/tap

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Stop = plosive Two phases:

Closure: airflow is completely blocked for a short timeRelease: an explosive sound as the air is released

Three types:Aspirated: closure + release + big puff of airUnaspirated: closure + release + small puff of airUnreleased stops: closure

Examples [國 ]: [p] 爸 , [pʰ] 怕 , [t ̪] 打 , [t ̪ʰ] 踏 , [k] 乾 , [kʰ] 看[閩 ]: [p] 爸 , [pʰ] 打 , [b] 肉 , [t ̪] 踏 , [t ̪ʰ] 桃 , [k] 菇 , [kʰ] 苦 , [g] 牛 , [p ̚] 十 , [t ̚] 結 , [k ̚] 角[E]: [p] spy, [pʰ] pie, [b] buy, [t] story, [tʰ] tie, [d] die, [k] sky, [kʰ] key, [g] guy

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voiceless

voiced

spy pie

buy

鼻皮

抹

narrow glottal opening wide glottal opening

to buy

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Nasal

Made by lowering the velum and allowing air to pass into the nasal cavity

Examples [國 ]: [m] 媽 , [n ̪] 拿 , [ŋ] 紅[閩 ]: [m] 媽 , [n ̪] 貓 , [ŋ] 紅[E]: [m] my, [n] new, [ŋ] sing

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Fricatives Process

Airflow is constricted but not cutoff completely

Turbulence is created

Two types

Sibilants: fricatives with high-pitched hissing noise

Nonsibilants: fricatives without high-pitched hissing noise

Examples

[國 ]: [f] 法 , [s ̪] 素 , [ʂ] 刪 , [ʐ] 然 , [ɕ] 先 , [x] 何[閩 ]: [s ̪] 素 , [z ̪] 熱 , [ɕ] 先 , [ʑ] 任 , [h] 何[E]: [f] few, [v] view, [θ] they, [ð] the, [s] sing, [z] zoo, [ʃ] she, [ʒ] garage, [h] high

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Affricates

Homorganic stop + fricative

Examples [國 ]: [t ̪s̪] 租 , [t ̪s̪ʰ] 粗 , [tʂ] 朱 , [tʂʰ] 出 , [tɕ] 家 , [tɕʰ] 恰[閩 ]: [t ̪s̪] 租 , [t ̪s̪ʰ] 粗 , [tɕ] 一 , [tɕʰ] 七[E]: [f] few, [v] view, [θ] they, [ð] the, [s] sing, [z] zoo, [tʃ] choice, [dʒ] job

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ApproximantTwo articulators are close together but not close enough to cause turbulent airflow

Two types:Approximant: air flows from the center of the tongue outward

Lateral approximant: air flows from the side(s) of the tongue outward

Examples [國 ]: [j] 牙 , [w] 娃 , [ɥ] 圓 , [l ̪] 來[閩 ]: [j] 厭 , [w] 歪 , [l ̪] 來[E]: [j] yes, [w] we, [l] like, [ɹ] read

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Tap/flapA quick motion of the tongue against a hard surface

Examples [閩 ]: [ɾ̪] 賊仔 [E]: [ɾ] butter

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Vowels are defined byTongue height

Tongue frontness/backness

Roundedness

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意欲思屋

矮黑可

辦棒

about

it

bet

bat

but bought

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Three types of vowelsMonophthongs

A vowel in which the tongue position does not change

Diphthongs A vowel in which the tongue position changes once

= VG/GV

(ex) [國 ]: [aɪ] 埃 , [eɪ] 黑 , [aʊ] 好 , [oʊ] 候 , [ja] 牙 , [wa] 娃 , [ɥɛ] 約(ex) [閩 ]: [ju] 油(ex) [E]: [ɔɪ] boy

Triphthongs A vowel in which the tongue position changes twice

= GVG

(ex) [國 ]: [jaʊ] 妖 , [jaɪ] 崖 , [waɪ] 歪

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SyllableConsonants and vowels combine to make a syllable

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PhonotacticsConstraints on which phones can follow each other in a language

[國 ] CCVC: 片[閩 ] CCVC: 接 [E] CCCVCCC: strengths

[E] CCVCCCC: twelfths

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Lexical stressA prominent syllable in a word that is determined by the lexicon

(ex) [國 ] 東西 [ˈtoŋɕi] vs. [ˈtoŋˈɕi]

Three levelsPrimary stress: dictionary

Secondary stress: dictionary

Unstressed: dictionary

In unstressed syllables, vowels can be Reduced: about [ə]

Unreduced: carry

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Sentence stress= pitch accent

A prominent syllable in an utterance that is determined by pragmatics

(ex) 連站都站不好！連戰都站不好！

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Phonological categories and pronunciation variation (1)

Pronunciations vary!

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Phoneme allophone/t/ [t, tʰ, ʔ, ʔt, ɾ, t ̚, t]̪

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(assimilation)

The degree of variation increases with more natural and colloquial speech

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Coarticulation The movement of articulators to anticipate the next sound or persevering movement from the last sound

(ex) nasalization, palatalization, voicing, etc.

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Distinctive features Binary variables which express some generalizations about groups of phonemes

Used to represent each phoneme as a matrix of feature values

Place features[labial], [coronal], [dorsal]

Manner features[consonantal], [vocalic], [continuant], [sonorant]

Voicing features[voice]

Vowel features[high], [low], [back], [round]

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Main use of featuresCapture natural articulatory classes of phones

Build articulatory feature detectors and use them to help phone detection

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Predicting phonetic variationPhonological rule

Caveat:Variation is a stochastic process

Many non-phonetic factors are important to this prediction task

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Factors influencing phonetic variationNon-phonetic

Speech rateWord frequencySpeaker’s state of mindMorphological boundariesSociolinguistic factors

Phonetic Intrinsic sound qualityProsodic boundariesCoarticulation

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Acoustic phonetics and signals (1)

Waves

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For computers to record and manipulate speech, it is necessary to perform analog-to-digital conversion

A two-step processSampling—limit the number of places after the decimal point on the time axis

Quantization—limit the number of places after the decimal point on the amplitude axis

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Sampling rate

Number of sample taken per second

At least two samples per cycle

Nyquist frequencythe highest frequency component that can be captured with a given sampling rate

= ½ sampling rate

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Frequency = 100 HzSampling rate = 200 HzNyquist frequency = 100 Hz

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signal not in the original signal aliasing

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Quantization Analogous to measuring the amplitudes in the waveform with a ruler

The main issue is the accuracy of the amplitude measurements

The most popular choices for the number of bits used to encode speech samples are 8, 12, and 16 bits

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Recording formatChannels: mono or stereo

Format: linear or compressed Linear: linear PCM

Compressed: -law log compression

Common format.wav, .aiff, .au

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Fundamental frequency = F0

Measures speed of vocal fold vibration

Hertz

AmplitudeMeasures amount of air pressure variation

Pascal (Pa)

RMS

IntensitySound power per unit area measuring at a listener’s location

Decibels (dB)

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Perceptual propertiesPitch

Mental sensation or perceptual correlate of F0

Mel scale

Loudness Perceptual correlated of power

Human ear has greater resolution in the low power range

Loudness interacts with frequency

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most sensitive

quick sensitivity drop

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1000 Hz 100 Hz

1x 2x 1x 2x

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Autocorrelation method

A pitch extraction algorithm that correlates the

signal with itself at various offsets

The offset that gives the highest correlation gives

the period of the signal

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Interpreting phones from a waveform

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FFT

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The source-filter model

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Phonetic resources

Pronunciation dictionariesCELEX

CMUdict

PRONLEX

Phonetically annotated corpusEnglish: TIMIT, Switchboard, Buckeye

German: Kiel corpus

Japanese: CSJ

Mandarin: AS, NTU (Taiwan), CASS (China)

Phonetic softwardsPRAAT

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Advanced: articulatory and gestural phonology (1)

Articulatory phonology

Represents a speech utterance as a sequence of

potentially overlapping articulatory gestures

Advantages:

Gesture scores are likely to be much better hidden

states at capturing the continuous nature of speech than

a discrete sequence of phones

Help model the fine-grained effects of coarticulation of

neighboring gestures

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Advanced: articulatory and gestural phonology (2)

Documents

Phonetics Janice Fon Graduate Institute of Linguistics National Taiwan University