Phonetics & PhonologyAn Introduction

Sarmad HussainCenter for Research in Urdu Language Processing, NUCES, Lahore, Pakistan sarmad.hussain@nu.edu.pk

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Levels of Linguistic Analysis

PragmaticsSemantics

SyntaxMorphology

Phonology

Phonetics

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Overview

Phonetics

Phonology

Computational Phonology

Phonetics

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What is Phonetics ?

Study of human speech as a physical phenomenon

Articulation

Acoustics

Perception

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Articulatory Phonetics

Study of how speech sounds are produced by human vocal apparatus

Anatomy of vocal organs

Air stream Mechanism

Voicing

Articulation

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Anatomy of Vocal Organs

[2]

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Air-stream Mechanisms

Pulmonic

Glottic

Velaric

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Pulmonic Sounds

Air flow is directed outwards towards the oral

cavity

Pressure built by compression of lungs

English [p], [n], [s], [l], [e]

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Glottic Egressive Sounds

Air flow is directed outwards towards the oral

cavity

Pressure built by pushing up closed glottis

Georgian [p’], [t’], [k’]

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Glottic Ingressive Sounds

Air flow is directed inwards from the oral

cavity

Pressure reduced by pulling down closed

glottis

Hausa, Sindhi [ɓ,ɠ ]

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Velaric Sounds

Air flow is directed inwards from the oral

cavity

Pressure reduced by forming velaric and

alveolar closure and pulling down tongue

clicks

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Articulatory Phonetics

Study of how speech sounds are produced by human vocal apparatus

Anatomy of vocal organs

Air stream Mechanism

Voicing

Articulation

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Bernoulli Effect

Air pumped from the lungs applies pressure on closed glottisHigh pressure opens vocal cordsHigh velocity air flow creates low pressure region pulling vocalcords together againProcess is repeated, producing vibrations in the vocal cords

[3]

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Voicing

Whisper

Creak

bhBreathy Voice

phAspirated

bVoice

pVoicelessness

[4]

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Articulation

Manners of Articulation

Places of Articulation

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Consonants – Manners of Articulation

Lateral

Trill

Tap

mNasal

jApproximant

dʒtʃAffricate

Fricative

pStop

[4]

Flap

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Places of Articulation

[2]

Labial

Alveolar

Dental

Labio-dental

PalatalVelar

Uvular

Pharyngeal

Laryngeal

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Consonants – Places of Articulation

[9]

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Consonants – Places of Articulation

Multiple Places of ArticulationGlottalPharyngealUvularVelar

dʒʃPalatalRetroflexAlveolarDentalLabio-dentalBilabial

[4]

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Consonantal Sounds

[10]

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Vowel – Features

Low / High

Back / Front

Round

Nasal

Long

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Vowel – Minimal Pairs

Bag Big (English)/bæg/ /bɪg/Beat bit/bit/ /bɪt/Boot bait/but/ /bet/

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/a/ Vocal Tract Outline

[11]

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Vocalic Inventory

ɒɑaLow

ʌæHigher-low

ɔʌœƐLower-mid

ΩɚəEMean-mid

oɤø=öeHigher-mid

ʊƗɪLower-high

uɯɨ=ʉy=üiHigh

RoundedUnroundedRoundedUnroundedRoundedUnrounded

BackCentralFront

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Vocalic Quadrilateral

[12]

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Diphthongs

Combination of two vocalic sounds

English: [aj] I, eye [aj]

[aw] cow [kaw]

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Gemination of Consonants

Double/long consonants

English: “misspell”, “unknown”

Urdu “ê 6”,“ 6”

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What is Phonetics ?

Study of human speech as a physical phenomenon

Articulation

Acoustics

Perception

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Periodic Sine Wave

PeriodTime to complete one cycle (sec)FrequencyNumber of cycles per second (Hertz)AmplitudeMaximum displacement of a periodic wave (dB)

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Complex Periodic Waves

Sinewaves contain a single frequencyComplex waves contain multiple frequency waves added togetherComplex periodic waves contain only Sine waves at base (fundamental) frequency (F0) and integral multiples of F0 (Fourier’s Theorem)

F0

Ampl

itude

Time

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Resonance

Response of a system is not constant for signals at all frequencies. The frequency which gives largest response is called Resonance (frequency).

F

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Sound WaveSound waves are formed by longitudinal movement of particles creating high and low pressure regions called compressions and rarefactions

Graph of pressure at each point in time

1 2 3 4

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Acoustic Phonetics

Source-Filter Model

Source

Filter

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Source-Filter Theory: Filter

Response curve with tongue in neutral position Resonances are called Formants (F1, F2, F3, …)

[15]

F2

F3

F1

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Source-Filter Theory: Source

Waveform and spectrum of the glottal pulse

[15]

Time

Ampl

itude

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Source-Filter Theory

Combining the two results in results in spectrum of short vowel ‘ə’ (schwa)

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Spectrogram

A spectrogram is a time-frequency-amplitude graph representing sound

“ a bab” “a dad” “a gag”

[16]

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Spectrogram

[17] [16]

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What is Phonetics ?

Study of human speech as a physical phenomenon

Articulation

Acoustics

Perception

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Speech Perception

Acoustic signal is highly variable but perception is very stable (invariant)How do map physical variance to perceptual invariance?

Intrinsic vs. extrinsic normalizationCategorical perceptionArticulatory Invariance - recreation of articulatory gesturesAcoustic Invariance - stable regions in speech within articulatory variability…?

Phonology

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What is Phonology?

Study of how sounds interact in various languages (phonetics conceptual representation)

Segmental phenomenaPhonemic Inventory and AllophonySound-change rules and ordering

Supra-segmental phenomenaSyllabificationProminenceTonesIntonation

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Phoneme?

Mental concept representing a physical sound

Many to many mapping between phoneme and a phone within a language

English /t/ aspirated in “tunafish”

unaspirated in “starfish”

dental before labio-dental

flapped in “buttercup”

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Phonological Features

Phoneme = set of features that are true at a given time for a particular phonemic unit (phonological features) (Auto-segmental theory)

Values of features can by unary or binary ( +/- for present/absent)

[18]

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Phonological Features

Contrastive function: Each phoneme differs from others in at least one featureDescriptive function: Accurately describes phonetic nature of a sound (may include redundant, non-contrastive features)

Classificatory function: Explains and allows generalizations and common phonological processes

[18]

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English Consonant Features

[18]

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English Vowel Features

[18]

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Phonological Rules

Humans are lazy so compromise articulation to reduce effortCompromise in Articulation changes the soundConstituents of a phonological rules are

Phonemes to be modified due to a ruleConditioning context in which the rule has to be firedChange that occurs in a sound after the rule has been fired

Rules are sometimes ordered in a language

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Types of Phonological Rules

AssimilationAddition of features due to neighboring phonemes

n [+bilabial] / __ [+bilabial, +voiced, +stop]

DissimilationDeletion of features due to neighboring phonemes

[7]

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Types of Phonological Rules

Insertion / DeletionAddition or deletion of an entire phone

MetathesisChange order of phonemes

prescribe => perscribeask => aks

[7]

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Syllable

A syllable is a unit of sound composed ofA central peak of sonority (usually a vowel), and Consonants that cluster around this central peak

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Syllable Structure

Syllable structure of Urdu word ن † /pɑkɪstɑn/

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Syllabification

Syllabification is the process of dividing words into syllables

Nuclear ProjectionMaximal Onset PrincipleSonority Sequencing Principle

Template based MatchingTemplates: V, CV, CVC, CVCCDirection of largest template application: RTL, LTR

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ProminenceSyllable(s) in a word may be more prominent than others Prominence can change meaning

Spanish: término, 'end' (noun), termíno, 'I'm finishing' terminó, 'she/he finished’

English‘ob.ject, ob.’ject‘con.tent, con.’tent

Syllable vs. stress timed languagesFinal heavy syllable is stressed, no secondary stress

Sensitive to segmental “quantity” or morasEvery odd syllable is stress, First has primary stress

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Intonation

You are going!You are going.You are going?

Intonation carries linguistic meaning, e.g. emotion, intention, etc.Realized primarily through variation of F0 over a sentenceMultiple theories of how intonation is computed and realized, e.g. Pierrehumbert (TOBI), IPO, Fujisaki, etc.

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Computational PhonologyLetter-to-sound rules (?)

Regular, heuristic, statisticalSound change rules

FSTRule base

Syllabification algorithmTemplate or sonority based algorithm

Stress-assignment algorithmStress-assignment algorithm

Intonation assignment algorithmRule-based algorithm – based on syntactic parse (?)Corpus based (Machine Learning) algorithmOther corpus based approaches

Thank you

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References1. http://www.mapsofworld.com/world-language-map.htm2. http://www.ling.upenn.edu/courses/Spring_2001/ling001/phonetics.html3. http://www.umanitoba.ca/faculties/arts/linguistics/russell/138/sec5/phonatio

.htm4. http://web.uvic.ca/ling/resources/ipa/5. http://www.ling.mq.edu.au/speech/phonetics/phonetics/airstream_laryngeal

/vot.html6. http://www.indiana.edu/~hlw/PhonUnits/consonants2.html7. http://www.ling.ohio-state.edu/~xflu/201/phonology.pdf8. http://encyclopedia.thefreedictionary.com/IPA%20in%20Unicode9. http://www.ling.upenn.edu/courses/Summer_2003/ling001/lecture4.html

10. http://encyclopedia.thefreedictionary.com/International%20Phonetic%20Al

phabet

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References11. http://www.haskins.yale.edu/Haskins/MISC/ASY/VOWELS/ah.html12. http://www.sil.org/mexico/ling/glosario/E005ei-VowelsChart.htm

13. http://people.deas.harvard.edu/~jones/cscie129/nu_lectures/lecture3%20/

formants1.gif14. http://www.umanitoba.ca/faculties/arts/linguistics/russell/138/sec4/formant

s.htm15. http://www.umanitoba.ca/faculties/arts/linguistics/russell/138/sec4/src-

filt.htm16. A Course in Phonetics by Peter Ladefoged

http://hctv.humnet.ucla.edu/departments/linguistics/VowelsandConsonants/course/contents.html

17. http://web.uvic.ca/ling/resources/ipa/18. Introduction to Phonetics and Phonology by Clark and Yallop

http://ifla.uni-stuttgart.de/~jilka/teaching/intro1/i3_features.pdf