A branch of linguistics studying how humans make sounds
The field of
articulatory phonetics
is a subfield of
phonetics
that studies articulation and ways that humans produce speech. Articulatory phoneticians explain how humans produce speech
sounds
via the interaction of different
physiological
structures. Generally, articulatory phonetics is concerned with the transformation of
aerodynamic
energy
into
acoustic
energy. Aerodynamic energy refers to the airflow through the
vocal tract
. Its
potential
form is
air pressure
; its
kinetic
form is the actual
dynamic
airflow. Acoustic energy is variation in the air pressure that can be represented as
sound waves
, which are then perceived by the human
auditory system
as sound.
[a]
Respiratory sounds
can be produced by expelling air from the lungs. However, to vary the sound quality in a way useful for speaking, two speech organs normally move towards each other to contact each other to create an obstruction that shapes the air in a particular fashion. The point of maximum obstruction is called the
place of articulation
, and the way the obstruction forms and releases is the
manner of articulation
. For example, when making a
p
sound, the lips come together tightly, blocking the air momentarily and causing a buildup of
air pressure
. The lips then release suddenly, causing a burst of sound. The place of articulation of this sound is therefore called
bilabial
, and the manner is called
stop
(also known as a
plosive
).
Components
[
edit
]
The vocal tract can be viewed through an aerodynamic-
biomechanic
model that includes three main components:
- air cavities
- pistons
- air valves
Air
cavities
are containers of air
molecules
of specific
volumes
and
masses
. The main air cavities present in the articulatory system are the supraglottal cavity and the subglottal cavity. They are so-named because the
glottis
, the openable space between the
vocal folds
internal to the
larynx
, separates the two cavities. The supraglottal cavity or the orinasal cavity is divided into an
oral subcavity
(the cavity from the glottis to the
lips
excluding the nasal cavity) and a
nasal subcavity
(the cavity from the velopharyngeal port, which can be closed by raising the
velum
). The subglottal cavity consists of the
trachea
and the
lungs
. The
atmosphere
external to the articulatory stem may also be considered an air cavity whose potential connecting points with respect to the body are the nostrils and the lips.
Pistons
are initiators. The term
initiator
refers to the fact that they are used to initiate a change in the volumes of air cavities, and, by
Boyle's Law
, the corresponding air
pressure
of the cavity. The term
initiation
refers to the change. Since changes in air pressures between connected cavities lead to airflow between the cavities, initiation is also referred to as an
airstream mechanism
. The three pistons present in the articulatory system are the larynx, the
tongue
body, and the physiological structures used to manipulate lung volume (in particular, the floor and the walls of the
chest
). The lung pistons are used to initiate a
pulmonic
airstream (found in all human languages). The larynx is used to initiate the
glottalic
airstream mechanism by changing the volume of the supraglottal and subglottal cavities via vertical movement of the larynx (with a closed glottis).
Ejectives
and
implosives
are made with this airstream mechanism. The tongue body creates a velaric airstream by changing the pressure within the oral cavity: the tongue body changes the mouth subcavity.
Click consonants
use the velaric airstream mechanism. Pistons are controlled by various
muscles
.
Valves
regulate airflow between cavities. Airflow occurs when an air valve is open and there is a pressure difference between the connecting cavities. When an air valve is closed, there is no airflow. The air valves are the vocal folds (the glottis), which regulate between the supraglottal and subglottal cavities, the velopharyngeal port, which regulates between the oral and nasal cavities, the tongue, which regulates between the oral cavity and the atmosphere, and the lips, which also regulate between the oral cavity and the atmosphere. Like the pistons, the air valves are also controlled by various muscles.
Initiation
[
edit
]
To produce any kind of sound, there must be movement of air. To produce sounds that people can interpret as spoken words, the movement of air must pass through the vocal folds, up through the throat and, into the mouth or nose to then leave the body. Different sounds are formed by different positions of the mouth?or, as linguists call it, "the oral cavity" (to distinguish it from the nasal cavity).
Consonants
[
edit
]
Consonants are speech sounds that are articulated with a complete or partial closure of the
vocal tract
. They are generally produced by the modification of an
airstream
exhaled from the lungs. The respiratory organs used to create and modify airflow are divided into three regions: the vocal tract (supralaryngeal), the
larynx
, and the subglottal system. The airstream can be either
egressive
(out of the vocal tract) or
ingressive
(into the vocal tract). In pulmonic sounds, the airstream is produced by the lungs in the subglottal system and passes through the larynx and vocal tract.
Glottalic
sounds use an airstream created by movements of the larynx without airflow from the lungs.
Click
consonants are articulated through the
rarefaction
of air using the tongue, followed by releasing the forward closure of the tongue.
Place of articulation
[
edit
]
Consonants are pronounced in the vocal tract, usually in the mouth. In order to describe the place of articulation, the
active and passive articulator
need to be known. In most cases, the active articulators are the lips and tongue. The passive articulator is the surface on which the constriction is created. Constrictions made by the lips are called
labials
. Constrictions can be made in several parts of the vocal tract, broadly classified into coronal, dorsal and radical places of articulation.
Coronal
articulations are made with the front of the tongue,
dorsal
articulations are made with the back of the tongue, and
radical
articulations are made in the
pharynx
.
These divisions are not sufficient for distinguishing and describing all speech sounds.
For example, in English the sounds
[s]
and
[?]
are both coronal, but they are produced in different places of the mouth. To account for this, more detailed places of articulation are needed based upon the area of the mouth in which the constriction occurs.
Labial consonants
[
edit
]
Articulations involving the lips can be made in three different ways: with both lips (bilabial), with one lip and the teeth (labiodental), and with the tongue and the upper lip (linguolabial).
Depending on the definition used, some or all of these kinds of articulations may be categorized into the class of
labial articulations
. Ladefoged and Maddieson (1996) propose that linguolabial articulations be considered coronals rather than labials, but make clear this grouping, like all groupings of articulations, is equivocal and not cleanly divided.
Linguolabials are included in this section as labials given their use of the lips as a place of articulation.
Bilabial consonants
are made with both lips. In producing these sounds the lower lip moves farthest to meet the upper lip, which also moves down slightly,
though in some cases the force from air moving through the aperture (opening between the lips) may cause the lips to separate faster than they can come together.
Unlike most other articulations, both articulators are made from soft tissue, and so bilabial stops are more likely to be produced with incomplete closures than articulations involving hard surfaces like the teeth or palate. Bilabial stops are also unusual in that an articulator in the upper section of the vocal tract actively moves downwards, as the upper lip shows some active downward movement.
Labiodental consonants
are made by the lower lip rising to the upper teeth. Labiodental consonants are most often
fricatives
while labiodental nasals are also typologically common.
There is debate as to whether true labiodental
plosives
occur in any natural language,
though a number of languages are reported to have labiodental plosives including
Zulu
,
Tonga
,
and
Shubi
.
Labiodental
affricates
are reported in
Tsonga
which would require the stop portion of the affricate to be a labiodental stop, though Ladefoged and Maddieson (1996) raise the possibility that labiodental affricates involve a bilabial closure like "pf" in German. Unlike plosives and affricates, labiodental nasals are common across languages.
Linguolabial consonants
are made with the blade of the tongue approaching or contacting the upper lip. Like in bilabial articulations, the upper lip moves slightly towards the more active articulator. Articulations in this group do not have their own symbols in the International Phonetic Alphabet, rather, they are formed by combining an apical symbol with a diacritic implicitly placing them in the coronal category.
They exist in a number of languages indigenous to
Vanuatu
such as
Tangoa
, though early descriptions referred to them as apical-labial consonants. The name "linguolabial" was suggested by
Floyd Lounsbury
given that they are produced with the blade rather than the tip of the tongue.
Coronal consonants
[
edit
]
Coronal consonants are made with the tip or blade of the tongue and, because of the agility of the front of the tongue, represent a variety not only in place but in the posture of the tongue. The coronal places of articulation represent the areas of the mouth where the tongue contacts or makes a constriction, and include dental, alveolar, and post-alveolar locations. Tongue postures using the tip of the tongue can be
apical
if using the top of the tongue tip,
laminal
if made with the blade of the tongue, or
sub-apical
if the tongue tip is curled back and the bottom of the tongue is used. Coronals are unique as a group in that every
manner of articulation
is attested.
Australian languages
are well known for the large number of coronal contrasts exhibited within and across languages in the region.
Dental consonants
are made with the tip or blade of the tongue and the upper teeth. They are divided into two groups based upon the part of the tongue used to produce them: apical dental consonants are produced with the tongue tip touching the teeth; interdental consonants are produced with the blade of the tongue as the tip of the tongue sticks out in front of the teeth. No language is known to use both contrastively though they may exist
allophonically
.
Alveolar consonants
are made with the tip or blade of the tongue at the alveolar ridge just behind the teeth and can similarly be apical or laminal.
Crosslinguistically, dental consonants and alveolar consonants are frequently contrasted leading to a number of generalizations of crosslinguistic patterns. The different places of articulation tend to also be contrasted in the part of the tongue used to produce them: most languages with dental stops have laminal dentals, while languages with alveolar stops usually have apical stops. Languages rarely have two consonants in the same place with a contrast in laminality, though
Taa
(?Xoo) is a counterexample to this pattern.
If a language has only one of a dental stop or an alveolar stop, it will usually be laminal if it is a dental stop, and the stop will usually be apical if it is an alveolar stop, though for example
Temne
and
Bulgarian
do not follow this pattern.
If a language has both an apical and laminal stop, then the laminal stop is more likely to be affricated like in
Isoko
, though
Dahalo
show the opposite pattern with alveolar stops being more affricated.
Retroflex consonants
have several different definitions depending on whether the position of the tongue or the position on the roof of the mouth is given prominence. In general, they represent a group of articulations in which the tip of the tongue is curled upwards to some degree. In this way, retroflex articulations can occur in several different locations on the roof of the mouth including alveolar, post-alveolar, and palatal regions. If the underside of the tongue tip makes contact with the roof of the mouth, it is sub-apical though apical post-alveolar sounds are also described as retroflex.
Typical examples of sub-apical retroflex stops are commonly found in
Dravidian languages
, and in some
languages indigenous to the southwest United States
the contrastive difference between dental and alveolar stops is a slight retroflexion of the alveolar stop.
Acoustically, retroflexion tends to affect the higher formants.
Articulations taking place just behind the alveolar ridge, known as
post-alveolar consonants
, have been referred to using a number of different terms. Apical post-alveolar consonants are often called retroflex, while laminal articulations are sometimes called palato-alveolar;
in the Australianist literature, these laminal stops are often described as 'palatal' though they are produced further forward than the palate region typically described as palatal.
Because of individual anatomical variation, the precise articulation of palato-alveolar stops (and coronals in general) can vary widely within a speech community.
Dorsal consonants
[
edit
]
Dorsal consonants are those consonants made using the tongue body rather than the tip or blade.
Palatal consonants
are made using the tongue body against the hard palate on the roof of the mouth. They are frequently contrasted with velar or uvular consonants, though it is rare for a language to contrast all three simultaneously, with
Jaqaru
as a possible example of a three-way contrast.
Velar consonants
are made using the tongue body against the
velum
. They are incredibly common cross-linguistically; almost all languages have a velar stop. Because both velars and vowels are made using the tongue body, they are highly affected by
coarticulation
with vowels and can be produced as far forward as the hard palate or as far back as the uvula. These variations are typically divided into front, central, and back velars in parallel with the vowel space.
They can be hard to distinguish phonetically from palatal consonants, though are produced slightly behind the area of prototypical palatal consonants.
Uvular consonants
are made by the tongue body contacting or approaching the uvula. They are rare, occurring in an estimated 19 percent of languages, and large regions of the Americas and Africa have no languages with uvular consonants. In languages with uvular consonants, stops are most frequent followed by
continuants
(including nasals).
Radical consonants
[
edit
]
Radical consonants either use the root of the tongue or the
epiglottis
during production.
Pharyngeal consonants
are made by retracting the root of the tongue far enough to touch the wall of the
pharynx
. Due to production difficulties, only fricatives and approximants can be produced this way.
Epiglottal consonants
are made with the epiglottis and the back wall of the pharynx. Epiglottal stops have been recorded in
Dahalo
.
Voiced epiglottal consonants are not deemed possible due to the cavity between the
glottis
and epiglottis being too small to permit voicing.
Glottal consonants
[
edit
]
Glottal consonants are those produced using the vocal folds in the larynx. Because the vocal folds are the source of phonation and below the oro-nasal vocal tract, a number of glottal consonants are impossible such as a voiced glottal stop. Three glottal consonants are possible, a voiceless glottal stop and two glottal fricatives, and all are attested in natural languages.
Glottal stops
, produced by closing the
vocal folds
, are notably common in the world's languages.
While many languages use them to demarcate phrase boundaries, some languages like
Huatla Mazatec
have them as contrastive phonemes. Additionally, glottal stops can be realized as
laryngealization
of the following vowel in this language.
Glottal stops, especially between vowels, do usually not form a complete closure. True glottal stops normally occur only when they are
geminated
.
Manner of articulation
[
edit
]
Knowing the place of articulation is not enough to fully describe a consonant, the way in which the stricture happens is equally important. Manners of articulation describe how exactly the active articulator modifies, narrows or closes off the vocal tract.
Stops
(also referred to as plosives) are consonants where the airstream is completely obstructed. Pressure builds up in the mouth during the stricture, which is then released as a small burst of sound when the articulators move apart. The velum is raised so that air cannot flow through the nasal cavity. If the velum is lowered and allows for air to flow through the nose, the result in a nasal stop. However, phoneticians almost always refer to nasal stops as just "nasals".
Affricates
are a sequence of stops followed by a fricative in the same place.
Fricatives
are consonants where the airstream is made turbulent by partially, but not completely, obstructing part of the vocal tract.
Sibilants
are a special type of fricative where the turbulent airstream is directed towards the teeth,
creating a high-pitched hissing sound.
Nasals
(sometimes referred to as nasal stops) are consonants in which there's a closure in the oral cavity and the velum is lowered, allowing air to flow through the nose.
In an
approximant
, the articulators come close together, but not to such an extent that allows a turbulent airstream.
Laterals
are consonants in which the airstream is obstructed along the center of the vocal tract, allowing the airstream to flow freely on one or both sides.
Laterals have also been defined as consonants in which the tongue is contracted in such a way that the airstream is greater around the sides than over the center of the tongue.
The first definition does not allow for air to flow over the tongue.
Trills
are consonants in which the tongue or lips are set in motion by the airstream.
The stricture is formed in such a way that the airstream causes a repeating pattern of opening and closing of the soft articulator(s).
Apical trills typically consist of two or three periods of vibration.
Taps
and
flaps
are single, rapid, usually
apical
gestures where the tongue is thrown against the roof of the mouth, comparable to a very rapid stop.
These terms are sometimes used interchangeably, but some phoneticians make a distinction.
In a tap, the tongue contacts the roof in a single motion whereas in a flap the tongue moves tangentially to the roof of the mouth, striking it in passing.
During a
glottalic airstream mechanism
, the glottis is closed, trapping a body of air. This allows for the remaining air in the vocal tract to be moved separately. An upward movement of the closed glottis will move this air out, resulting in it an
ejective consonant
. Alternatively, the glottis can lower, sucking more air into the mouth, which results in an
implosive consonant
.
Clicks
are stops in which tongue movement causes air to be sucked in the mouth, this is referred to as a
velaric airstream
.
During the click, the air becomes
rarefied
between two articulatory closures, producing a loud 'click' sound when the anterior closure is released. The release of the anterior closure is referred to as the click influx. The release of the posterior closure, which can be velar or uvular, is the click efflux. Clicks are used in several African language families, such as the
Khoisan
and
Bantu
languages.
Vowels
[
edit
]
Vowels are produced by the passage of air through the
larynx
and the
vocal tract
. Most vowels are
voiced
(i.e. the vocal folds are vibrating). Except in some marginal cases, the vocal tract is open, so that the airstream is able to escape without generating fricative noise.
Variation in vowel quality is produced by means of the following articulatory structures:
Articulators
[
edit
]
Glottis
[
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]
The
glottis
is the opening between the vocal folds located in the
larynx
. Its position creates different vibration patterns to distinguish voiced and voiceless sounds.
[49]
In addition, the
pitch
of the vowel is changed by altering the frequency of vibration of the
vocal folds
. In some languages there are contrasts among vowels with different
phonation
types.
[50]
Pharynx
[
edit
]
The pharynx is the region of the vocal tract below the velum and above the larynx. Vowels may be made
pharyngealized
(also
epiglottalized
,
sphincteric
or
strident
) by means of a
retraction of the tongue root
.
[50]
: 306?310
Vowels may also be articulated with
advanced tongue root
.
[49]
: 298
There is discussion of whether this vowel feature (ATR) is different from the Tense/Lax distinction in vowels.
[50]
: 302?6
Velum
[
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]
The velum?or soft palate?controls airflow through the nasal cavity. Nasals and nasalized sounds are produced by lowering the velum and allowing air to escape through the nose. Vowels are normally produced with the
soft palate
raised so that no air escapes through the nose. However, vowels may be
nasalized
as a result of lowering the soft palate. Many languages use nasalization contrastively.
[50]
: 298?300
Tongue
[
edit
]
The tongue is a highly flexible organ that is capable of being moved in many different ways. For vowel articulation the principal variations are
vowel Height
and the dimension of
Backness
and
frontness
.
[50]
A less common variation in vowel quality can be produced by a change in the shape of the front of the tongue, resulting in a
rhotic
or rhotacized vowel.
[50]
Lips
[
edit
]
The lips play a major role in vowel articulation. It is generally believed that two major variables are in effect:
lip-rounding
(or labialization) and
lip protrusion
.
Airflow
[
edit
]
For all practical purposes,
temperature
can be treated as
constant
in the articulatory system. Thus,
Boyle's Law
can usefully be written
as the following two equations.
- [51]
- [52]
What the above equations express is that given an initial
pressure
P
1
and
volume
V
1
at time 1 the
product
of these two values will be equal to the product of the pressure
P
2
and volume
V
2
at a later time 2. This means that if there is an increase in the volume of cavity, there will be a corresponding decrease in pressure of that same cavity, and vice versa. In other words, volume and pressure are
inversely proportional
(or negatively correlated) to each other. As applied to a description of the subglottal cavity, when the lung pistons contract the lungs, the volume of the subglottal cavity decreases while the subglottal air pressure increases. Conversely, if the lungs are expanded, the pressure decreases.
A situation can be considered where (1) the vocal fold valve is closed separating the supraglottal cavity from the subglottal cavity, (2) the mouth is open and, therefore, supraglottal air pressure is equal to atmospheric pressure, and (3) the lungs are
contracted
resulting in a subglottal pressure that has increased to a pressure that is greater than atmospheric pressure. If the vocal fold valve is subsequently opened, the previously two separate cavities become one unified cavity although the cavities will still be aerodynamically isolated because the glottic valve between them is relatively small and constrictive.
Pascal's Law
states that the pressure within a system must be equal throughout the system. When the subglottal pressure is greater than supraglottal pressure, there is a pressure inequality in the unified cavity. Since pressure is a
force
applied to a
surface area
by definition and a force is the product of
mass
and
acceleration
according to
Newton's Second Law of Motion
, the pressure inequality will be resolved by having part of the mass in air
molecules
found in the subglottal cavity move to the supraglottal cavity. This movement of mass is airflow. The airflow will continue until a pressure equilibrium is reached. Similarly, in an
ejective consonant
with a
glottalic
airstream mechanism
, the lips or the tongue (i.e., the buccal or lingual valve) are initially closed and the closed glottis (the laryngeal piston) is raised decreasing the oral cavity volume behind the valve closure and increasing the pressure compared to the volume and pressure at a resting state. When the closed valve is opened, airflow will result from the cavity behind the initial closure outward until intraoral pressure is equal to
atmospheric pressure
. That is, air will flow from a cavity of higher pressure to a cavity of lower pressure until the equilibrium point; the pressure as
potential energy
is, thus, converted into airflow as
kinetic energy
.
Sound sources
[
edit
]
Sound sources refer to the conversion of aerodynamic energy into acoustic energy. There are two main types of sound sources in the articulatory system: periodic (or more precisely semi-periodic) and aperiodic. A periodic sound source is vocal fold vibration produced at the glottis found in vowels and voiced consonants. A less common periodic sound source is the vibration of an oral articulator like the tongue found in alveolar trills. Aperiodic sound sources are the turbulent noise of fricative consonants and the short-noise burst of plosive releases produced in the oral cavity.
Voicing
is a common period sound source in spoken language and is related to how closely the
vocal cords
are placed together. In English there are only two possibilities,
voiced
and
unvoiced
. Voicing is caused by the vocal cords held close by each other, so that air passing through them makes them vibrate. All normally spoken vowels are voiced, as are all other sonorants except
h
, as well as some of the remaining sounds (
b
,
d
,
g
,
v
,
z
,
zh
,
j
, and the
th
sound in
this
). All the rest are voiceless sounds, with the vocal cords held far enough apart that there is no vibration; however, there is still a certain amount of audible friction, as in the sound
h
. Voiceless sounds are not very prominent unless there is some turbulence, as in the stops, fricatives, and affricates; this is why sonorants in general only occur voiced. The exception is during
whispering
, when all sounds pronounced are voiceless.
Periodic sources
[
edit
]
- Non-vocal fold vibration: 20?40
hertz
(cycles per second)
- Vocal fold vibration
- Lower limit: 70?80 Hz modal (bass), 30?40 Hz creaky
- Upper limit: 1170 Hz (soprano)
Vocal fold vibration
[
edit
]
Experimental techniques
[
edit
]
Palatography
[
edit
]
In order to understand how sounds are made, experimental procedures are often adopted.
Palatography
is one of the oldest instrumental phonetic techniques used to record data regarding articulators.
[54]
In traditional, static palatography, a speaker's palate is coated with a dark powder. The speaker then produces a word, usually with a single consonant. The tongue wipes away some of the powder at the place of articulation. The experimenter can then use a mirror to photograph the entire upper surface of the speaker's mouth. This photograph, in which the place of articulation can be seen as the area where the powder has been removed, is called a palatogram.
[55]
Technology has since made possible
electropalatography
(or EPG). In order to collect EPG data, the speaker is fitted with a special prosthetic palate, which contains a number of electrodes. The way in which the electrodes are "contacted" by the tongue during speech provides phoneticians with important information, such as how much of the palate is contacted in different speech sounds, or which regions of the palate are contacted, or what the duration of the contact is.
See also
[
edit
]
Notes
[
edit
]
- ^
Although sound is just air pressure variations, the variations must be at a high enough rate to be perceived as sound. If the variation is too slow, it will be inaudible.
References
[
edit
]
- ^
a
b
"Laver, John
Principles of Phonetics
, 1994, Cambridge University Press
- ^
a
b
c
d
e
f
"Peter Ladefoged and Ian Maddieson
The Sounds of the World's Languages
, 1996, Blackwell;
ISBN
0-631-19815-6
- ^
Stated in a less abbreviatory fashion: pressure
1
× volume
1
= pressure
2
× volume
2
- ^
volume
1
divided by sum of volume
1
and change in volume = sum of pressure
1
and the change in pressure divided by pressure
1
- ^
Niebergall, A; Zhang, S; Kunay, E; Keydana, G; Job, M; et al. (2010).
"Real-time MRI of Speaking at a Resolution of 33 ms: Undersampled Radial FLASH with Nonlinear Inverse Reconstruction"
.
Magn. Reson. Med
.
69
(2): 477?485.
doi
:
10.1002/mrm.24276
.
PMID
22498911
.
S2CID
21057863
.
.
- ^
Ladefoged, Peter (1993).
A Course In Phonetics
(3rd ed.). Harcourt Brace College Publishers. p. 60.
- ^
Palatography
Citations
[
edit
]
- Baumbach, E. J. M (1987).
Analytical Tsonga Grammar
. Pretoria: University of South Africa.
- Doke, Clement M (1926).
The Phonetics of the Zulu Language
. Bantu Studies. Johannesburg: Wiwatersrand University Press.
- Fujimura, Osamu (1961). "Bilabial stop and nasal consonants: A motion picture study and its acoustical implications".
Journal of Speech and Hearing Research
.
4
(3): 233?47.
doi
:
10.1044/jshr.0403.233
.
PMID
13702471
.
- Guthrie, Malcolm (1948).
The classification of the Bantu languages
. London: Oxford University Press.
- International Phonetic Association (1999).
Handbook of the International Phonetic Association
. Cambridge University Press.
- International Phonetic Association (2015).
International Phonetic Alphabet
. International Phonetic Association.
- Keating, Patricia; Lahiri, Aditi (1993). "Fronted Velars, Palatalized Velars, and Palatals".
Phonetica
.
50
(2): 73?101.
doi
:
10.1159/000261928
.
PMID
8316582
.
S2CID
3272781
.
- Ladefoged, Peter (1960). "The Value of Phonetic Statements".
Language
.
36
(3): 387?96.
doi
:
10.2307/410966
.
JSTOR
410966
.
- Ladefoged, Peter (2001).
A Course in Phonetics
(4th ed.). Boston:
Thomson/Wadsworth
.
ISBN
978-1-413-00688-9
.
- Ladefoged, Peter (2005).
A Course in Phonetics
(5th ed.). Boston:
Thomson/Wadsworth
.
ISBN
978-1-413-00688-9
.
- Ladefoged, Peter
; Johnson, Keith (2011).
A Course in Phonetics
(6th ed.). Wadsworth.
ISBN
978-1-42823126-9
.
- Ladefoged, Peter; Maddieson, Ian (1996).
The Sounds of the World's Languages
. Oxford: Blackwell.
ISBN
978-0-631-19815-4
.
- Lodge, Ken (2009).
A Critical Introduction to Phonetics
. New York: Continuum International Publishing Group.
ISBN
978-0-8264-8873-2
.
- Maddieson, Ian (1993). "Investigating Ewe articulations with electromagnetic articulography".
Forschungberichte des Intituts fur Phonetik und Sprachliche Kommunikation der Universitat Munchen
.
31
: 181?214.
- Maddieson, Ian (2013).
"Uvular Consonants"
. In Dryer, Matthew S.; Haspelmath, Martin (eds.).
The World Atlas of Language Structures Online
. Leipzig: Max Planck Institute for Evolutionary Anthropology.
- Scatton, Ernest (1984).
A reference grammar of modern Bulgarian
. Slavica.
ISBN
978-0893571238
.
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