Phonetics Janice Fon Graduate Institute of Linguistics National Taiwan University.

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Phonetics

Janice Fon

Graduate Institute of Linguistics

National Taiwan University

Overview

Speech sounds and phonetic transcription

Articulatory phonetics

Phonological categories and pronunciation variation

Acoustic phonetics and signals

Phonetic resources

Advanced: articulatory and gestural phonology

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

Phonetic alphabetsIPA

Standard developed by International Phonetic Association

Alphabet + principles of transcription

ARPAbetDesigned for American English in ASCII symbols

Computer-friendly

Articulatory phonetics (1)

Definition:The study of how phones are produced

The vocal organ

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

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

Place of articulation

coronal

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

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

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

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

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

Glottal Sounds made at the glottis

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

Retroflex Sounds made with the tongue tip curled back

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

Manner of articulationStop

Fricative

Affricates

Approximant

Flap/tap

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

voiceless

voiced

spy pie

鼻皮

narrow glottal opening wide glottal opening

to buy

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

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

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

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

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

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

Vowels are defined byTongue height

Tongue frontness/backness

Roundedness

意欲思屋

矮黑可

辦棒

but bought

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

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

SyllableConsonants and vowels combine to make a syllable

PhonotacticsConstraints on which phones can follow each other in a language

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

[E] CCVCCCC: twelfths

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

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！

Phonological categories and pronunciation variation (1)

Pronunciations vary!

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

(assimilation)

The degree of variation increases with more natural and colloquial speech

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

(ex) nasalization, palatalization, voicing, etc.

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]

Main use of featuresCapture natural articulatory classes of phones

Build articulatory feature detectors and use them to help phone detection

Predicting phonetic variationPhonological rule

Caveat:Variation is a stochastic process

Many non-phonetic factors are important to this prediction task

Factors influencing phonetic variationNon-phonetic

Speech rateWord frequencySpeaker’s state of mindMorphological boundariesSociolinguistic factors

Phonetic Intrinsic sound qualityProsodic boundariesCoarticulation

Acoustic phonetics and signals (1)

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

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

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

signal not in the original signal aliasing

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

Recording formatChannels: mono or stereo

Format: linear or compressed Linear: linear PCM

Compressed: -law log compression

Common format.wav, .aiff, .au

Fundamental frequency = F0

Measures speed of vocal fold vibration

AmplitudeMeasures amount of air pressure variation

Pascal (Pa)

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

Decibels (dB)

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

most sensitive

quick sensitivity drop

1000 Hz 100 Hz

1x 2x 1x 2x

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

Interpreting phones from a waveform

The source-filter model

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

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

Advanced: articulatory and gestural phonology (2)

Phonetics Janice Fon Graduate Institute of Linguistics National Taiwan University.

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