ECE 598: The Speech Chain

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ECE 598 The Speech Chain

• Lecture 9 Consonants

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Today

• International Phonetic Alphabet
• History
• SAMPA an IPA for ASCII
• Sounds with a Side Branch
• Nasal Consonants
• Reminder Impedance of a uniform tube
• Liquids /l/, /r/
• Events in the Release of a Syllable-Initial Stop
  Consonant
• Transient and Frication Sources
• Aspiration
• Formant Transitions

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Topic 1International Phonetic Alphabet
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International Phonetic Alphabet Purpose and
Brief History

• Purpose of the alphabet to provide a universal
  notation for the sounds of the worlds languages
• Universal If any language on Earth
  distinguishes two phonemes, IPA must also
  distinguish them
• Distinguish Meaning of a word changes when
  the phoneme changes, e.g. cat vs. bat.
• Very Brief History
• 1446 King Sejong of Chosen publishes a
  distinctive-feature based phonetic notation for
  Korean.
• 1867 Alexander Melville Bell publishes a
  distinctive-feature-based universal phonetic
  notation in Visible Speech The Science of the
  Universal Alphabetic. His notation is rejected
  as being too expensive to print.
• 1886 International Phonetic Association founded
  in Paris by phoneticians from across Europe
  begins developing IPA notation.
• 1991 Unicode provides a standard method for
  including IPA notation in computer documents.

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International Phonetic Alphabet Vowels
SAMPA i / y I / Y e / 2 E / 9 a
SAMPA ? / u U ? / o V / O A / Q
_at_ 3
SAMPA An international standard for the ASCII
transcription of the IPA phonemes. Maps most
IPA phones to the ASCII printable characters.
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Vowels Sample WordsFrom http//www.phon.ucl.ac.u
k/home/sampa/american.htmWith phonological
feature annotation. All are syllabic.

• Lax Vowels -reduced,lax,-blade lax like
  IPA central, but also short duration
• I pit pIt high,front high like
  IPA close.
• E pet pEt -high,front
• V cut kVt -high,-front
• U put pUt high,-front
• Tense Vowels -reduced,-lax
• i ease iz -low,high,front low
  like IPA open. Specified if -high,-lax
• e raise rez -low,-high,front
• pat pt low,front
• u lose luz -low,high,-front,round
  round
• o nose noz -low,-high,-front,round
  possible if -lax,-front
• O cause kOz low,-front,round
• A pot fAD_at_ low,-front,-round
• Classic Diphthongs
• aI rise raIz
• OI noise nOIz
• aU rouse raUz
• Schwa and Syllabic /r/
• 3 furs f3z -reduced,lax,blade,-an
  terior,-distributed

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IPA Regular Consonants
Tongue Body
Tongue Blade
?
gq
k
t
d
p
b
n
m
N
4
h
B f v T D s z S Z
C x G
r
j
l
L
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Obstruent Consonants Sample WordsFrom
http//www.phon.ucl.ac.uk/home/sampa/american.htm
With phonological feature annotation. All are
-syllabic.

• Stops -sonorant,-continuant
• p pin pIn lips,-round,-voice
• b bin bIn lips,-round,voice
• t tin tIn blade,anterior,-distributed,-voic
  e anterior of the alveolar ridge
• d din dIn blade,anterior,-distributed,voice
  distributed tongue tip flat
• k kin kIn body,high,-voice
• g give gIv body,high,voice
• Affricates -sonorant,-continuant
• tS chin tSIn blade,-anterior,distributed,-voi
  ce
• dZ gin dZIn blade,-anterior,distributed,voic
  e
• Fricatives -sonorant,continuant
• f fin fIn lips,-round,-voice
• v vim vIm lips,-round,voice
• T thin TIn blade,anterior,distributed,-voice
  
• D this DIs blade,anterior,distributed,voice
  
• s sin sIn blade,anterior,-distributed,-voice
  
• z zin zIn blade,anterior,-distributed,voice
  
• S shin SIn blade,-anterior,distributed,-voice
  
• Z measure mEZ_at_ blade,-anterior,distributed,v
  oice

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Doubly-Articulated Consonants
SAMPA w H
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Sonorant Consonants Sample WordsMostly from
http//www.phon.ucl.ac.uk/home/sampa/american.htm
With phonological feature annotation

• Flap sonorant,-continuant,-nasal,-syllabic
• 4 butter bV43 blade,anterior,-distribu
  ted
• Nasals sonorant,-continuant,nasal
• m mock mAk lips,-round,-syllabic
• n knock nAk blade,anterior,-distribut
  ed,-syllabic
• n button bV4n blade,anterior,-distributed,
  syllabic
• N thing TIN body,high,-syllabic
• Liquids sonorant,continuant,-syllabic
• r wrong rON blade,-anterior,-distribut
  ed
• l long lON blade,anterior,-distri
  buted
• Glides sonorant,continuant,-syllabic
• w wasp wAsp lips,round
• j yacht jAt blade,-anterior,-distr
  ibuted

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Examples SAMPA

• You wish to know all about my grandfather. Well,
  he is nearly ninety-three years old, but he still
  thinks as swiftly as ever.
• ju wIS tu no Al _at_baUt maI grndfaD_at_r. wEl, hi iz
  nirli naInti-Tri yirz old, bVt hi stIl Tinks z
  swIftli z Ev_at_r.

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Example Phonological Feature Matrix
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Non-Pulmonic Consonants
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Topic 2Sounds with Side Branches Nasal
Consonants, /l/, /r/
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Nasal Murmur
the mug
the nut
sing a song
Observations Low-frequency resonance (about
300Hz) always present Low-frequency resonance
has wide bandwidth (about 150Hz) Energy of
low-frequency resonance is very constant Most
high-frequency resonances cancelled by
zeros Different places of articulation have
different high frequency spectra High-frequency
spectrum is talker-dependent and variable
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Acoustic Description of Vocal Tract with a Side
Branch
UN(0,w)
AP
AM
UP(0,w)
UM(0,w)
x
-LP
0
LM

• Continuity Equations at the Juncture (x0)
• Conservation of mass
• uP(0,w)uN(0,w)uM(0,w)0
• Continuity of pressure
• pP(0,w)pN(0,w)pM(0,w)

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Reminder How to Calculate Impedance of a Uniform
Tube

• Express u(x,w), p(x,w) in terms of p and p-
• p(x,w) pe-jwx/c p-ejwx/c
• u(x,w) A v(x,w) (A/rc)(pe-jwx/c - p-ejwx/c)
• Impose one boundary condition
• u(L,w)0 p- pe2jwL/c
• ... or
• p(L,w)0 p- -pe2jwL/c
• Calculate impedance at the other boundary
• z(0,w) p(0,w)/v(0,w) (rc)(pp-)/(p-p-)
• ... or
• z(0,w) p(0,w)/u(0,w) (rc/A)(pp-)/(p-p-)
• Result (for a uniform tube, using zp/u)
• u(L,w)0 z(0,w) j(rc/A)cot(wL/c)
• or
• p(L,w)0 z(0,w) -j(rc/A)tan(wL/c)

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Resonant Frequencies (Formants) of a Nasal
Consonant

• Air Flow from Pharynx must equal Air Flow to Nose
  and Mouth
• uPuNuM0
• Therefore, the admittances sum to zero
• (1/zP)(1/zN)(1/zM)0
• Plug in the true admittances
• -j(AP/rc)tan(wLP/c)j(AN/rc)cot(wLN/c)-j(AM/rc)tan
  (wLM/c)0
• For most resonant frequencies Eq. (3) must be
  solved numerically on a computer (or graphically,
  as in Fujimura, JASA 1962)

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First Nasal Formant

• The true resonance equation
• -jAPtan(wLP/c)jANcot(wLN/c)-jAMtan(wLM/c)0
• Low-frequency approximation
• -AP(wLP/c)AN/(wLN/c)-AM(wLM/c)0
• -(AMLMAPLP)(w/c)2AN/LN0
• w2 c2(AN/LN)/(AMLMAPLP)
• Typical example, nasal F1
• APLP60cm3, AMLM40cm3,
• AN/LN(3.5cm2/9cm) 2/5cm
• F1(c/2p)(1/250)1/2 350Hz

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Nasal Consonant Formants Resonances of the
Oral-Nasal-Pharyngeal Combined System
Fourth Nasal Resonance 2400
Third Nasal Resonance 1800
Second Nasal Resonance 1400
First Nasal Resonance 350Hz, with broad
bandwidth B 300Hz
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Nasal Consonant Anti-Resonances

• Anti-Resonances (zeros) occur because of energy
  lost into the side-branch
• Continuity of pressure at the juncture
• pP(0,w)pN(0,w)pM(0,w)
• If it turns out that pN(0,w)0, thats OK thats
  just part of the normal standing wave pattern in
  the nostrils.
• If it turns out that pM(0,w)0, thats extra it
  means that the side branch (into the mouth) is
  draining away all of the energy that would
  otherwise go out through the nostrils.

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Nasal Consonant Anti-Resonances

• Anti-Resonances (zeros) occur at any frequency
  such that, regardless of uM(0,w), pM(0,w) is
  required to be zero
• In other words zM(0,w)pM/uM0
• Uniform tube zM(0,w)(rc/AM)cot(wLM/c)
• Therefore Fzm(mc/2LM)-(c/4LM)
• Anti-resonances of the English nasal consonants
• /m/ LM 8cm, Fzm 1100, 3300, 5500Hz
• /n/ LM 5cm, Fzm 1700, 5100, 8500Hz
• /ng/ LM 2cm, Fzm 4400Hz,

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Liquids

• /l/
• Main airway around the tongue (on both sides, so
  there may be zeros because of added transfer
  functions)
• Side branch above the tongue
• L 6cm
• FZ 35400/4L 1500Hz, between F2 and F3, pushes
  F2 down
• /r/
• Main airway as in a vowel
• Side branch under the tongue
• L 3.5cm
• FZ 2500Hz, between F3 and F4, pushes F3 down

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Topic 3Events in the Release of a Stop
(Plosive) Consonant
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Events in the Release of a Stop
Burst transient frication (the part of the
spectrogram whose transfer function has poles
only at the front cavity resonance frequencies,
not at the back cavity resonances).
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Events in the Release of a Stop
Transient
Frication
Aspiration
Voicing
Aspirated (/t/)
Unaspirated (/b/)
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Pre-voicing during Closure
To make a voiced stop in most European
languages Tongue root is relaxed, allowing
it to expand so that vocal folds can continue to
vibrating for a little while after oral
closure. Result is a low-frequency voice
bar that may continue well into closure. In
English, closure voicing is typical of read
speech, but not casual speech.
the bug
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Transient The Release of Pressure
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Transfer Function During Transient and Frication
Poles
Turbulence striking an obstacle makes noise
Front cavity resonance frequency FR c/4Lf
Example FR2250 c/4Lf Lf 4cm the shutter
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Transfer Function During Frication An Important
Zero
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Transfer Function During Frication An Important
Zero
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Transfer Function During Aspiration
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Formant Transitions A Perceptual Study
The study (1) Synthesize speech with different
formant patterns, (2) record subject responses.
Delattre, Liberman and Cooper, J. Acoust. Soc.
Am. 1955.
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Perception of Formant Transitions
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Summary

• International Phonetic Alphabet
• Distinct distinguishes words
• Universal distinct any language ? distinct in
  IPA
• Sounds with a Side Branch
• Polespoles of entire system (oral-nasal-pharyngea
  l)
• Zerosresonances of side branch (P0 at juncture)
• Events in the Release of a Syllable-Initial Stop
  Consonant
• Transient pop, triangular shape, about 0.5ms
  long
• Frication turbulence at the constriction, about
  5ms
• Aspiration turbulence at glottis, 0-70ms
• Formant Transitions may start during aspiration
  (in the case of an unvoiced stop release)