Airstream mechanisms and VOT
Dr. Christian DiCanio
cdicanio@buffalo.edu
University at Buffalo
10/1/15 - 10/6/15
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Preliminaries
Where we’ve been...
We’re almost done covering most of the basic aspects of articulatory
phonetics
1
English phonology and phonetics
2
Place of articulation
3
Manner of articulation
4
Articulatory methods
5
Speech aerodynamics
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Preliminaries
Where we’re going this week and next
Finishing up articulatory phonetics
1
Airstream mechanisms
2
Phonation type
3
VOT
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Preliminaries
Where we’re going later...
1
Acoustic phonetics (next week)
2
Source-filter theory of speech production
3
Vowel acoustics
4
Stop/fricative acoustics
5
Spectrogram reading and Praat training
6
Phonetic fieldwork
7
Prosody, suprasegmentals, and tone
8
Hearing, speech perception
9
Phonological/phonetic features
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Airstream mechanisms
Airstream mechanisms
The majority of speech sounds in human languages are generated via air
coming out of the lungs. This is a pulmonic airstream mechanism.
However, articulations made in the oral cavity can be generated by other
means of moving airflow.
The source/manner of generating airflow in speech articulations is called
an airstream mechanism.
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Airstream mechanisms
What are the possible closed cavities here?
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Airstream mechanisms
Flow types
Ingressive airflow involves movement of the airflow into the oral
cavity.
Egressive airflow involves movement of the airflow out of the oral
cavity.
For a pulmonic airstream mechanism, most speech sounds are produced
with egressive airflow. Though, some small exceptions exist, such as the
Swedish/Danish “ja” ‘yes’, which may be uttered with pulmonic ingressive
airflow.
Also, English “Huh!”, indicating shock, is uttered with ingressive airflow
(but perhaps little voicing).
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Airstream mechanisms
Non-pulmonic airstream mechanisms
However, it is not just airflow into or out of the lungs that is the source of
sound.
A glottalic airstream mechanism involves closure made at the glottis
(a glottal stop, [P]) and either upward or downward movement of the
larynx to create airflow.
A velaric airstream mechanism involves closure made at the velum
(with or without velic closure) and compression of the anterior
constriction to create airflow.
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Airstream mechanisms
Glottalic egressives
If there is glottal closure and the larynx is raised during the production of
an obstruent, the pressure behind the constriction will increase.
Glottalic egressives, or ejectives are produced when the oral constriction is
released prior to a release of the glottal closure.
The airflow is forced outward (egressive) since air particles at higher
pressure will move to lower (atmospheric) pressure.
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Airstream mechanisms
Steps in ejectives
(Ladefoged and Johnson, 2011:137)
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Airstream mechanisms
Ejective types
Ejectives are transcribed with an apostrophe after the consonant, e.g. [k’,
s’, x’, tS’].
Since ejectives are produced with glottal closure, they are always voiceless.
The velum must also remain raised. Why do you think that is?
Ejectives occur in 16.8% of the world’s languages, including in many
Semitic languages, Caucasian languages, and among many different
families within the Americas (Salish, Athabaskan, Wakashan,
Otomanguean, Mayan, etc) (Maddieson, 2013).
See Salish examples from Praat.
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Airstream mechanisms
Lakhota contrasts ejectives at three places of articulation
Bilabial
p’o
‘foggy’
paGõt”a
‘mallard’
px a
‘bitter’
DiCanio (UB)
Dental
”t’uSE
‘at all costs’
”tuwa
‘who’
”tx awa
‘bridge’
Airstream/VOT
Velar
k’u
‘to give’
kah
‘that’
kx ant”a
‘plum’
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Airstream mechanisms
Ejective acoustics
The release of the consonant constriction always precedes the glottal
closure release, sometimes by a significant duration. Example below from
Ixcatec word [tS’u] ‘chocolate’
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Airstream mechanisms
Ejective stops are more common in the world’s languages than ejective
fricatives.
It is difficult to maintain high oral air pressure above the glottis for the
release while simultaneously producing enough airflow for the turbulence.
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Airstream mechanisms
Glottalic ingressives
It is also possible to lower the larynx with a glottalic airstream, producing
a glottalic ingressive, or implosive.
Lowering the larynx during the production of an oral stop decreases the
oral cavity volume and thus lowers intra-oral air pressure relative to
atmospheric pressure.
Upon release of the oral closure, air rushes in. The glottis is then released
(usually for the onset of a vowel) and the airflow moves in the opposite
direction (a pulmonic egressive).
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Airstream mechanisms
Steps in implosives
(Ladefoged and Johnson, 2011:141)
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Airstream mechanisms
Implosive types
Implosives are transcribed with a rightward hook at the top of the
consonant, e.g. [á, â, ê].
Implosives may be voiced or voiceless. However, voiceless implosives are
rather rare. Expansion of the oral cavity volume is a mechanism that will
decrease the intra-oral air pressure, thus facilitate voicing. Why?
Implosives occur in 13.2% of the world’s languages, including in many
Nilo-Saharan, Niger-Congo, and the Chadic branch of Afro- Asiatic
languages. They are also found in certain Southeast Asian languages
(Austroasiatic, Tai-Kadai) (Maddieson, 2013).
See Sindhi examples on UCLA lab archive.
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Airstream mechanisms
Implosive acoustics
The normal production of voicing involves a decay in the amplitude of
vocal fold vibration due to air pressure equalization.
With implosives, the increased volume of the oral cavity allows voicing to
continue and even to increase in amplitude. An example of this is found in
nguistics
Theory
of Science,
University
Gothenburg
Mpiemo,and
a Bantu
language
(Nagano-Madsen
andofThornell,
2012)
an
The
in
ce.
of
in
ond
ere
Figure 3 (a). Speaker A.
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Airstream mechanisms
Voicing may continue for longer in the production of implosives given the
increased oral cavity volume (and its lower pressure).
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Airstream mechanisms
Velaric ingressives
It is also possible to seal the oral cavity at the velum with dorso-velic
closure for the formation of a velaric ingressive, or click.
Closure at the lips, teeth, alveolar ridge, or alveopalatal region is made and
the tongue body and jaw are lowered.
This produces a decrease in pressure and increase in volume within the
cavity, so that upon release, airflow rushes inward (ingressive).
Following release of the front constriction, dorso-velar constriction is
released to produce either a concomitant velar nasal or velar stop.
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Airstream mechanisms
Steps in click formation
(Ladefoged and Johnson, 2011:144)
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Airstream mechanisms
Click types
Clicks are transcribed using different characters in the IPA, [ò, |, !, }, {].
The velum may be either raised or lowered during click production and the
> >
>
simultaneous velar stops may be voiced, [N|, g|], voiceless unaspirated [k|],
>h
or aspirated [k| ].
Clicks are rare in the world’s languages, though they may be used as
non-contrastive speech sounds in many languages.
They are found primarily in Khoisan languages, spoken in Southern Africa,
in addition to languages that have had contact with Khoisan, such as Zulu
(Bantu). Only 1.8% of the world’s languages have clicks and they are
geographically bound.
See Xhosa examples on UCLA lab archive.
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Airstream mechanisms
Click aerodynamics
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Noise is generated in the production of a click from the sudden change in
pressure across the constriction. Given that the post-velar portion of the
oral cavity is small, expansion of this cavity by any means drastically
decreases air pressure causing substantial airflow.
'
'
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DiCanio (UB)
'
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J*;0+.'=!N'O0/&(6D7*&&.$'%A+3,*A'-/.0$(-%,%&.'@*&1'%&&%A1.$'&04*);?'0/.$'&('6.%/0+.'&1.'
*)&+%(+%,'-+.//0+.'*)'A,*AF/G'
'
'
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Airstream mechanisms
Clicks in Zulu
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$
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Airstream mechanisms
Very high ingressive airflow occurs at release, but this is over a very short
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interval in time.
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Phonation type and VOT
VOT
VOT refers to voice onset time, which reflects the lag between the
release of a stop consonant and the onset of voicing.
Truly voiced stops have a negative VOT because voicing begins prior
to the stop closure release.
Voiceless unaspirated stops have a VOT near 0, since voicing begins
immediately after the stop closure release.
Voiceless aspirated stops have a VOT greater than 0, since voicing
begins after aspiration.
See examples in Praat.
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Phonation type and VOT
Determining VOT
We can determine VOT by measuring the time between the stop burst
release, which appears as a short duration transient (aperiodic noise), and
the onset of regular, periodic vocal fold vibration.
Exactly what we categorize as phonetically voiced, voiceless unaspirated,
and voiceless aspirated can vary substantially by language.
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Phonation type and VOT
Voiceless unaspirated stops
¹. Cho & P. ¸adefoged
220
Figure 5. VOTs (ms) for the unaspirated coronal stops. (The Dahalo alveolar
stops, which have anomalous VOTs, have been omitted).
(Cho and Ladefoged, 1999)
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Phonation type and VOT
Voiceless aspirated stops
Figure 5. VOTs (ms) for the unaspirated coronal stops. (The Dahalo alveolar
stops, which have anomalous VOTs, have been omitted).
Figure 6. VOTs (ms) for the aspirated coronal stops.
a more extended contact area) might have been expected to have a slower release, and
(Cho andhence
Ladefoged,
a signi"cantly1999)
longer VOT. But it seems that the length of the contact is not an
important source of di!erences in VOT for the coronal stops in these languages.
The di!erences between bilabial stops and coronal stops are also not signi"cant. Many
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voicing that each language
has.
Banawa
H , for example, has only a single velar stop, with
Phonation
type
and VOT
no contrast in voicing; the mean VOT for this stop is 44 ms, placing it in the second
group. But both Western and Eastern Aleut also have only one velar stop; their mean
values are 78 and 95 ms, making them fully aspirated stops. Similarly, it does not matter
whether a language contrasts voiceless unapirated stops with aspirated stops. Both
Velar stops
Figure 9. Mean VOTs (ms) for velar stops across languages. The rectangles
enclose four regions, representing what might be called unaspirated stops, slightly
aspirated stops, aspirated stops and highly aspirated stops.
(Cho and Ladefoged, 1999)
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Summary
Key Concepts
Ingressive/Egressive airflow
Pulmonic airstream mechanisms
Glottalic airstream mechanisms (ejectives, implosives)
Velaric airstream mechanisms (clicks)
Constraints on combining other gestures with various airstream
mechanisms.
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Summary
Cho, T. and Ladefoged, P. (1999). Variation and universals in VOT: evidence from 18
languages. Journal of Phonetics, 27:207–229.
Ladefoged, P. and Johnson, K. (2011). A Course in Phonetics. Wadsworth: Cengage Learning,
6th edition.
Maddieson, I. (2013). Glottalized consonants. In Haspelmath, M., Dryer, M., Matthew, S., Gil,
D., and Comrie, B., editors, The World Atlas of Language Structures Online, chapter 7.
Munich: Max Planck Digital Library, Accessed on 2/10/2014.
Nagano-Madsen, Y. and Thornell, C. (2012). Acoustic properties of implosives in Bantu
Mpiemo. FONETIK, pages 1–4.
Thomas-Vilakati, K. D. (2010). Coproduction and Coarticulation in IsiZulu Clicks, volume 144
of University of California Publications in Linguistics. University of California Press.
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