Recap
Phonetic analysis of vowels (phân tích
của nguyên âm)
• Periodic speech waves are complex: they are made up
of a simple waves with different frequencies.
Cơ sở âm vị học và ngữ âm học
• The various component frequencies (harmonics) in a
complex wave can be displayed as a spectrum.
Lecture 12
Recap
Recap
• One way in which spectra of speech sounds differ is in
the relative intensity of their harmonics.
• Periodic speech waves are complex: they are made up
of a simple waves with different frequencies.
• The various component frequencies (harmonics) in a
complex wave can be displayed as a spectrum.
Formants
• These relative maxima in the spectra of vowels are
Formants
• These relative maxima in the spectra of vowels are
called formants and reflect the shape of the vocal tract
(hình dáng của đường dẫn âm).
called formants and reflect the shape of the vocal tract
(hình dáng của đường dẫn âm).
• Different shapes of the vocal tract, which cause the air to
• Different shapes of the vocal tract, which cause the air to
vibrate at different natural frequencies, or resonances
(cộng hưởng)
vibrate at different natural frequencies, or resonances
(cộng hưởng)
Resonance (cộng hưởng)
Resonance (cộng hưởng)
• When vibration hits a surface, it resonates at a
• When vibration hits a surface, it resonates at a
frequency determined by the size of the cavity
frequency determined by the size of the cavity
– small cavities resonate at high frequencies (filled bottle)
– large cavities resonate at low frequencies (empty bottle)
– small cavities resonate at high frequencies (filled bottle)
– large cavities resonate at low frequencies (empty bottle)
• Depending on the size of the mouth and throat cavities,
• Depending on the size of the mouth and throat cavities,
harmonics at certain frequencies are boosted, giving rise
to the formants that can be observed in the spectrum.
harmonics at certain frequencies are boosted, giving rise
to the formants that can be observed in the spectrum.
• The first formant is F1 (about 300Hz in [i] and 800Hz in
[a]); the second formant is F2 (about 2100Hz in [i] and
1250Hz in [a]); etc.
A. Spectrum of the vowel [a]
H1(=F0)
Harmonics emph. by F1
H2
Harmonics emphasized by F2
0
500
1000
1500 2000 2500
Frequency (Hz)
3000
3500
A formant is not the same as a harmonic!
• F1 and F2 play a crucial role in distinguishing vowels;
the higher formants are of less importance.
A formant is
not the same
as a
harmonic!
Formants 6= harmonics
Formants 6= harmonics
• Harmonics are whole-number multiples of F0
– i.e., a function of pitch (F0)
• Harmonics are whole-number multiples of F0
– i.e., a function of pitch (F0)
• Formants are resonant frequencies of a cavity
– e.g., the vocal tract
• Formants are resonant frequencies of a cavity
– e.g., the vocal tract
• It is possible to change one without changing the other.
• It is possible to change one without changing the other.
Formants 6= harmonics
How?
• Harmonics are whole-number multiples of F0
– i.e., a function of pitch (F0)
• Formants are resonant frequencies of a cavity
– e.g., the vocal tract
• It is possible to change one without changing the other.
• The source (nguồn) and filter
(bộ lọc) are independent!
• The vocal fold vibrations are
the source (F0)
• The vocal tract is the filter
(resonant frequencies)
Fant (1960), Acoustic Theory of
Speech Production
How?
The source-filter model
• The source (nguồn) and filter
(bộ lọc) are independent!
• The vocal fold vibrations are
the source (F0)
• The vocal tract is the filter
(resonant frequencies)
Fant (1960), Acoustic Theory of
Speech Production
Resonances of the vocal tract
[i] high front vowel!
F1
[u] high back vowel!
F2
• F1 reflects vowel height;
• F2 reflects vowel backness.
F1
[ɑ] low back vowel
Visualising the vowel space
F2
F1 F2
From Ladefoged (1996)
Elements of Acoustic
Phonetics.
• Plotting F1 against F2 for
each vowel of a given
language provides a
detailed representation of
the vowel system.
From Hillenbrand et al., 1995
Visualising the vowel space
Visualising the vowel space
• F1 reflects vowel height;
• F1 reflects vowel height;
• F2 reflects vowel backness.
• F2 reflects vowel backness.
• Plotting F1 against F2 for
• Plotting F1 against F2 for
each vowel of a given
language provides a
detailed representation of
the vowel system.
each vowel of a given
language provides a
detailed representation of
the vowel system.
From Hillenbrand et al., 1995
Visualising the vowel space
• F1 reflects vowel height;
From Hillenbrand et al., 1995
“Rules of thumb”
• Tongue height is inversely related to F1: the higher the
tongue/vowel, the lower the F1 note: this is actually a lie
• F2 reflects vowel backness.
• The more back the vowel, the lower the F2 (but other
• Plotting F1 against F2 for
things can lower F2 as well)
each vowel of a given
language provides a
detailed representation of
the vowel system.
– for front vowels, there is a gap between F1 and F2
– for back vowels, F1 and F2 are fairly close together
From Hillenbrand et al., 1995
“Rules of thumb”
Visualising the vowel space
Vowel charts tend to be plotted with inverted axes – why?
• Tongue height is inversely related to F1: the higher the
tongue/vowel, the lower the F1 note: this is actually a lie
1000
200
900
• The more back the vowel, the lower the F2 (but other
things can lower F2 as well)
#
800
300
æ
&
700
500
400
&
%
&
Visualising the vowel space
&
800
i
1000
$
700
!
u
1500 2000 2500
F2 (Hertz)
#
æ
900
1000
3000
3000
%
"
600
300
200
u
!
500
"
600 $
– for front vowels, there is a gap between F1 and F2
– for back vowels, F1 and F2 are fairly close together
i
400
2500
2000 1500
F2 (Hertz)
1000
Men, women, and children
Women tend to produced higher vowels than men – why?
4000
2000
Vowel charts tend to be plotted with inverted axes – why?
heed [i]
300
400
u
!
%
&
$
"
hid [I]
x
x
x
x
800
æ
900
2500
2000 1500
F2 (Hertz)
x
#
had [æ]
1000
x
x
hood [U]
500
x x
x
x
&
x
x
x
x
Who d [u]
x
x
x
head [E]
500
200
x
i
700
1000
3000
x
x
500
600
1000
x
x
200
F2(Hz)
x
x
x
Male
Female
Child
hawed [O]
hud [µ]
1000
x
hod [A]
1500
SashaofCalhoun
AcPh Lec3
Vowels
General American English (based onL2B
Peterson
& Barney, 1952).
20
Dialect variation
Interpreting formants
Formants can be useful for distinguishing between dialects.
3000
2500
Hz
2000
1500
1000
500
0
i
e
a
o
u
• Formant frequencies of
• Can you locate the
vowels /i E æ u o A/ ?
/i e a o u/
(from Deterding 1997 and Watson et al. 1998)
Rounded vowels
• Rounded vowels are produced with the lips slightly
protruded and rounded
• What effect might this have on the formants?
Rounded vowels
• Rounded vowels are produced with the lips slightly
protruded and rounded
• What effect might this have on the formants?
Rounded vowels
Rounded vowels
• Protruding the lips lengthens the oral cavity...
• Protruding the lips lengthens the oral cavity...
• Thus, lip rounding lowers the value of F2 (and F3).
• Thus, lip rounding lowers the value of F2 (and F3).
• So, for example, F1 of [y] as in French [vy] ‘view’ is
• So, for example, F1 of [y] as in French [vy] ‘view’ is
similar to F1 of [vi] ‘life’, but with lower F2 and F3.
similar to F1 of [vi] ‘life’, but with lower F2 and F3.
Rounded vowels
3000
2500
• Protruding the lips lengthens the oral cavity...
Hz
2000
1500
1000
• Thus, lip rounding lowers the value of F2 (and F3).
500
• So, for example, F1 of [y] as in French [vy] ‘view’ is
0
i
y
similar to F1 of [vi] ‘life’, but with lower F2 and F3.
• Where does /W/ fit into this chart?
u