CS 551652:

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CS 551/652 Structure of Spoken Language Lecture
2 Spectrogram Reading and Introductory
Phonetics John-Paul Hosom Fall 2008
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Spectrogram Reading Why bother?? Whats the
point of spectrogram reading? Do people read
spectrograms as part of their job? Do computers
read spectrograms in order to recognize
speech? There are some jobs that require
spectrogram reading (e.g. phonetic time
alignment), but not many. Automatic speech
recognition systems do not process speech in this
way. Primary reason for spectrogram reading If
youre going to work on a problem, its advisable
to understand the nature of that problem.
Spectrogram reading provides a direct method for
hands-on learning of the characteristics of
speech. Studying phonetics, signal processing,
or techniques in speech recognition/speech
synthesis does not fully convey of the complexity
and structure of spoken language.
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A great website on spectrogram reading
http//home.cc.umanitoba.ca/robh/ includes
how to tips on spectrogram reading, a
monthly mystery spectrogram, and archives of
past months spectrograms.
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Phonetics Introduction Phonology A
description of the systems and patterns of
sounds that occur in a language (abstract),
often involving comparisons between languages
and/or evolution of a language over
time. Phonetics A branch of phonology that
deals with individual speech sounds, their
production, and their written representation.
Phoneme A unit of speech that can be used
to differentiate words (e.g. cat /k ae t/
vs. bat /b ae t/). Phonemes identify
minimal pairs in a language. The set of
phonemes in a language subject to
interpretation most languages have 20 to 40
phonemes.
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Phonetics Introduction Allophone A speech
sound constituting one of the systematic phonetic
variants of a given phoneme. Different
allophones are predictable from environment
(e.g. toe, caught, fitness, writer
sill, still, spill) Phone An acoustic
realization of a phoneme. (Many different
phones may represent the same phoneme.) The
phoneme /s/ consists of more than 100
allophones - Pickett, The Acoustics of Speech
Communication, p. 7. Phonemes indicated by / /
phones (allophones) indicated by .
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Phonetics Introduction Syllable Unit of
speech containing one or more phonemes. A
vowel in a syllable is called the syllable
nucleus. Most syllables contain one vowel (or
diphthong) some contain only a lateral
(bott/le) or nasal (butt/on) as the most
intense sound. Syllable boundaries sometimes
ambiguous (tas/ty vs. tast/y vs.
ta/sty) Coarticulation The blending of two
or more adjacent phones, causing a non-distinct
boundary between them. Coarticulation is caused
by smooth changes in the articulators
(lips, tongue, jaw) over time.
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Phonetics Introduction Coarticulation Example
y
uw
aa
r
you are /y uw aa r/
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• Phonetics Introduction (adapted from Schane, p.
  4-6)
• Speech signal is continuous we perceive
  discrete entities.
• (How many sound units are in the word cat?)
• One assumption of phonology utterances can be
  represented as
• sequence of discrete units.
• Are such units purely an invention of
  linguistics?
• Spoonerisms (belly jeans vs. jelly beans)
  and rhymes indicate small units of language
  (Reverend William Archibald Spooner (1844-1930))
• Utterances of the same word(s) have many
  differences were
• usually only interested in those differences
  that are linguistically
• significant or that are perceived as
  different.
• Implies a somewhat subjective nature to
  phonology, whereas
• we want an objective measure of perceived or
  produced units.

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Phonetics Distinctive Phonetic Features
Phonemes do not differ randomly from one another
there are relationships among phonemes (e.g.
/p/ vs. /t/ vs. /ah/) A (distinctive)
feature is a phonetic property that can be
used to classify sounds Ladefoged, p. 42
Typically, features are associated with
aspects of articulation Features may be
binary or multi-valued Capital letters
indicate feature name Manner square brackets
indicate feature value fricative
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Phonetics Distinctive Phonetic Features
Exact set of features and feature values depends
on goals (no right or wrong set of
features or values) Distinctive features
provide a vocabulary for describing speech
Are distinctive features purely an invention of
linguistics? memory tasks show that when people
forget a phoneme, theyusually remember a phoneme
with similar distinctive features
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Phonetics Distinctive Phonetic Features
nasal tract
(hard) palate
velic port
oral tract
alveolar ridge
velum (soft palate)
lips
tongue
teeth
pharynx
tongue tip
glottis(vocal folds and space between vocal
cords)
vocal folds (larynx) vocal cords
The Speech Production Apparatus (from Olive, p.
23)
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Phonetics Distinctive Phonetic Features
Feature Description
_ Consonantal produced
with a constriction along center line of oral
cavity. Only vowels, /w/, /h/, and /y/ are not.
Vocalic largely unobstructed vocal tract.
Vowels and liquids (/l/, /r/) are vocalic
glides (/w/, /y/) are not. Anterior point of
articulation near alveolar ridge, including all
labial and dental sounds. Coronal articulation
involves front of tongue Continuant no complete
obstruction in oral cavity only nasals, stops,
and affricates are non-continuant
Strident articulation with long, narrow
constriction such as /s/, /z/, /f/, /v/, /sh/,
/zh/, /ch/, /jh/ Voiced vibration of the vocal
folds occurs during articulation
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Phonetics Distinctive Phonetic Features
Feature Description
_ Lateral contact
between corona of tongue and roof of
mouth, with lowering of sides of tongue (only
/l/ in English) Nasal lowering of the velic
port and opening of nasal cavity. High vowel
with high tongue position (narrow
constriction) in English, /iy/, /ih/, /uh/,
/uw/ Low vowel with low tongue position (no
constriction) /ae/, /ao/, /aa/ are (some) low
vowels in English. Back vowels produce with
tongue toward back of mouth /uw/, /uh/, /ah/,
/ao/, /aa/, /ow/ are back vowels
Round articulation involving rounding of the
lips only /uw/, /ow/, /ao/, and /uh/ are
rounded in English. However, /uh/ may take an
unrounded form. Adapted from Language by
C.E.Cairns and F. Williams in Normal Aspects of
Speech, Hearing, and Language, edited by
Minifie, Hixon, and Williams, 1973, p. 424, as
printed in Daniloff p. 51.
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Phonetics More Distinctive Phonetic Features
Feature Description
_ Sonorant resonant
quality of a sound vowels are
sonorant, stops and fricatives are sonorant.
nasals also sonorant. Syllabic is the phoneme the
main sound in a syllable? vowels are syllabic,
stops are usually syllabic, but there are
syllabic nasals and liquids. Tense tense vowels
are longer, more fully articulated, and more
distinct, e.g. /iy ey uw ow aa/ lax
vowels are less so, e.g. /ih eh uh
ah/. Aspirated produced without a constriction in
the vocal tract, but also without voicing
(/h/). Glottalized produced with aperiodic or
extremely low-frequency vibrations of the vocal
cords. Diphthong a single phoneme composed of two
or more other phonemes in sequence (/ay/, /oy/,
/ei/, /aw/, /ow/) from Schane, pp. 26-32
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Phonetics Distinctive Phonetic Features
Physiological Features Manner stop /p/,
fricative /s/, affricate /ch/, liquid /l/,
/r/, glide /j/, /w/, nasal /m/, vowel /ah/,
aspiration /h/ Place bilabial /p/,
labiodental /f/, dental /th/, alveolar
/t/, palato-alveolar /r/, palatal /sh/, velar
/k/, glottal /h/, front /iy/, mid /ah/, back
/aa/ (can combine mid back)
Height high /iy/, mid-high /ih/, mid /ax/,
mid-low /eh/, low /aa/ or high /iy/, mid /eh/,
low /aa/ (3 values, plus tense/lax)
Tenseness, Nasality, Rounding same as previous
descriptions
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Phonetics Distinctive Feature Relationships
Vowels
from Schane, pp. 12-13. /ax/ is slightly more
centralized than /ah/, and shorter in duration
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• Phonetics Distinctive Phonetic Features The
  Case of /ae/
• /ae/ is classified in the preceding table as
  lax, but we have been considering it as
  tense.
• One Rule for Differentiating Tense/Lax
• A lax vowel can never be a word-final stressed
  vowel
• e.g. /iy/ can be word final be /b iy/, tea
  /t iy/
• /ih/ can not be word final in one-syllable
  word /b ih/, /t ih/
• /ah/ can be word final, but only if
  unstressed.
• According to this rule, both /eh/ and /ae/ are
  lax, because they can not be word-final stressed
  vowels. In this case, the tense vowel in
  contrast to /eh/ is /ey/.
• However, /ae/ is long in duration (e.g. Forgie
  and Forgie (1959) and Peterson and Lehiste
  (1960)), making it acoustically more similar to a
  tense vowel.
• For spectrogram reading, were more concerned
  with acoustics, so well call /ae/ a tense vowel,
  although others may call it lax.

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• Phonetics Distinctive Phonetic Features The
  Case of /ae/
• Looking at 130,000 words in the CMU dictionary
• PHN CNT PCNT EXAMPLES
• /iy/ 12945 0.10002
• /ih/ 15 0.00012 chui, des, kiwani, lui,
  moishe, pih, to
• /eh/ 30 0.00023 bienvenue, des, eh,
  moshe, yahweh, zeh
• /ae/ 5 0.00004 dhaka, lashua, losoya,
  pah, yeah
• /uw/ 714 0.00552
• /uh/ 2 0.00002 lheureux, milieu
• /ah/ 6413 0.04955
• /aa/ 170 0.00131
• /ao/ 243 0.00188
• /ey/ 962 0.00743
• /ay/ 379 0.00293
• /oy/ 167 0.00129
• /yu/ 171 0.00132
• /aw/ 226 0.00175
• /ow/ 5137 0.03969

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Phonetics Distinctive Feature Relationships
Vowels
Front Central Back
iy
ju
uw
High
ih
uh
ey
ix
ow
oy
Mid
aw
ax
ay
ao
eh
ah
Low
ae
aa
from Ladefoged, pp. 38, 81, 218 with correction
to /aw/
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Phonetics Distinctive Feature Relationships
Consonants
approximant obstruent
from Olive, p. 28 and Daniloff, p. 56
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Phonetics Distinctive Feature Relationships
Consonants
from Ladefoged, p. 44
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Approximants Terminology

• Approximants are NOT the same as
  Semi-Vowels (although Rabiner states they
  are the same). American English /r/ is
  debatable, but well exclude it from the
  Semi-Vowels for consistency. (Ladefoged p. 229)
• Approximants can be divided into two groups
  Liquids and Glides Liquid /l/, /r/, Glide
  /w/, /y/ (Again, Rabiner confuses things
  by mixing up these sets)
• Lateral /l/
• Retroflex /r/, /er/, /axr/. (In some
  cases, /er/ is considered a retroflex but /r/
  isnt well keep things simple by calling
  /r/ a retroflex).
• Central Approximants /r/, /w/, /y/,
  Lateral Approximant /l/

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Approximants Terminology
Approximant
Semi-Vowel / Glide
Liquid
Lateral
/y/
/w/
Retroflex
/r, er, axr/
/l/
central approximants
lateral approximant