Chapter
1
1.1. What Does Phonetics Mean?
Phonetics,
the study of the sounds of human speech, is one area of specialization within
the field of linguistics. Unlike semantics, which deals with
the meaning of words, phonetics is focused exclusively on the properties of
speech sounds and their production.
Within phonetics,
there are three main areas of analysis:
Although phonetics might seem like a relatively
obscure area of study, it has a surprisingly long history. Approximately 2,500
years ago, ancient Indian grammarian, Panini, documented the
articulation of consonants in his treatise on the Sanskrit language.
A
working knowledge of phonetics is useful even if you're not planning a career
as a linguist. Speech therapists use phonetics to help
people suffering from communication disorders learn to improve their spoken
language skills. Foreign language teachers often incorporate phonetics as a
tool to show their students how speech sounds are similar across different
languages. Singers and actors use phonetics when they must replicate the speech
styles of various characters in their daily work.
Before launching into our discussion of articulatory phonetics, it would be
useful to discuss the IPA and its use for transcribing English.
Writing uses graphic symbols to represent speech sounds. All systems of
writing in use today represent the sounds of language. This connection can be
viewed in two ways.
a.)
From sound to writing. Every written language has a system of rules for how to spell the
spoken word. These rules are called the orthography, the writing rules
of the language.
b.)
From writing to sound. Every written language has a system of rules for pronouncing correctly what is
written. These rules are called orthoepy, or pronouncing rules.
Some writing systems come close to achieving a one-to-one correspondence
between sound and written symbol. In Spanish, for instance, the rules of
orthography and orthoepy are extremely simple. Once you have learned the
Spanish alphabet, spelling and reading Spanish words is relatively
unproblematical. Nearly every letter has one basic pronunciation, and most
basic sounds can be written with one and only one letter (exceptions being the
sound [s], which may be written s, c, z). The Georgian writing system comes
even closer to perfect economy. There are 33 different sounds in Georgian
and only 33 different letters in the Georgian alphabet. Whenever you hear
a new Georgian word, you know exactly how to write it. And whenever you meet a
new word in reading a Georgian text, you know exactly how it should be
pronounced; and whenever you hear a new Georgian word pronounced, you know
exactly how to write it.
Other languages, such as English, show far less economy of correspondence
between sound and written symbol. The English alphabet has only 26
letters. However, English spells one and the same sound with several
different letters depending upon the word. Consequently, one letter or
group of letters can be read in any one of several possible ways, such as the gh
in rough, ghost, night. The correspondence between sound and letter in
English frequently involves meaning as well as sound. Often, one must
know the meaning of an English word to pronounce or write it correctly: meet/meat;
through/threw.
Chapter II
2.1 Acoustic
phonetics
“When
we speak to each other, the sounds that we make have to travel from the mouth
of the speaker to the ear of the listener. This is true whether we are speaking
face to face, or by telephone over thousands of miles. What is important for us
in our study of speech is that this acoustic signal is completely observable:
we can capture everything the listener hears in the form of a recording, and
then measure whichever aspect of the signal that we want to know about.”
(Roach, P., 2001, p. 39)
The
study of acoustic phonetics was greatly enhanced in the late 19th century by
the invention of the Edison phonograph. The phonograph allowed the speech
signal to be recorded and then later processed and analyzed. By replaying the
same speech signal from the phonograph several times, filtering it each time
with a different band-pass filter,
a spectrogram of the speech utterance could be built
up. A series of papers by Ludimar Hermann
published in Pflügers Archiv
in the last two decades of the 19th century investigated the spectral
properties of vowels and consonants using the Edison phonograph, and it was in
these papers that the term formant
was first introduced. Hermann also played back vowel recordings made with the
Edison phonograph at different speeds to distinguish between Willis' and Wheatstone's
theories of vowel production.
On
a theoretical level, speech acoustics can be modeled in a way analogous to electrical circuits.
Lord
Rayleigh was among the first to recognize that the new electric
theory could be used in acoustics, but it was not until 1941 that the circuit
model was effectively used, in a book by Chiba and Kajiyama called "The
Vowel: Its Nature and Structure". (Interestingly, this book by Japanese
authors working in Japan was published in English at the height of World War
II.) In 1952, Roman Jakobson,
Gunnar Fant, and Morris Halle wrote "Preliminaries to Speech
Analysis", a seminal work tying acoustic phonetics and phonological theory
together. This little book was followed in 1960 by Fant "Acoustic Theory
of Speech Production", which has remained the major theoretical foundation
for speech acoustic research in both the academy and industry. (Fant was
himself very involved in the telephone industry.) Other important framers of
the field include Kenneth N. Stevens,
Osamu Fujimura, and Peter Ladefoged.
2.2 Articultory
phonetics
All speech sounds are made in this area. None are made outside of it
(such as by stomping, hand clapping, snapping of fingers, farting, etc.) Theoretically,
any sound could be used as a speech sound provided the human vocal tract is
capable of producing it and the human ear capable of hearing it. Actually
only a few hundred different sounds or types of sounds occur in languages known
to exist today, considerably fewer than the vocal tract is capable of
producing. Thus, all speech sounds result from air being somehow
obstructed or modified within the vocal tract.
This involves 3
processes working together:
a)
the airstream process--the source of air used in making the sound.
b)
the phonation process--the behavior of the vocal cords in the glottis during the production
of the sound.
c)
the oro-nasal process--the modification of that flow of air in the vocal track (from the
glottis to the lips and nose).
The airstream process
The first major way to categorize sounds according to phonetic features is by
the source of air. Where does the air come from that is modified by the
vocal organs? Languages can use any of three airstream mechanisms to
produce sounds.
One airstream mechanism is by far the most important for producing sounds in
the world's languages. Most sounds in the world's languages are produced
by manipulating air coming into the vocal tract as it is being exhaled by the
lungs, a method referred to as the pulmonic egressive airstream
mechanism. Sounds made by manipulating air as it is exhaled from the
lungs are called pulmonic egressive sounds. Virtually all sounds
in English and other European languages are produced by manipulating exhaled
air. And most sounds in other languages are also pulmonic
egressive.
There is another variety of this pulmonic airstream mechanism. Inhaled air can
also be modified to produce speech sounds. This actually occurs in a few
rare and special cases, such as in Tsou, an aboriginal language of Taiwan,
which has inhaled [f] and [h] ([h5/˝ps˝] ashes; [f5/tsuju], egg). Such
sounds are called pulmonic ingressive sounds, and the airstream
mechanism for making such sounds is called the ingressive rather than the
egressive version of the pulmonic airstream mechanism. Perhaps
because it is physiologically harder to slow down an inhalation than an
exhalation, pulmonic ingressive sounds are extremely rare.
The majority of the sounds in all languages of the world are pulmonic egressive
sounds. However, in addition to using air being actively exhaled (or
inhaled), two other airstream mechanisms are used to produce some of the sounds
in some of the world's languages.
1) To understand the second airstream mechanism, the glottalic airstream
mechanism, let's first look at a special pulmonic egressive sound, the
glottal stop. Air being exhaled from the lungs may be stopped in the throat by
a closure of the glottis. This trapping of air by the glottis is called a
glottal stop. English actually has a glottal stop in certain
exclamations: [u?ow], u?u], [a?a], and in certain dialectical
pronunciations: [bottle]. The IPA renders the glottal stop as a question
mark without the period.
The glottal stop itself is an example of a pulmonic egressive sound, since air
from the lungs is being stopped. However, the glottis can be closed
immediately before the production of certain other sounds, trapping a pocket of
air in the vocal tract. If this reservoir of stationary air is then
manipulated in the production of a sound it yields another type of airstream
mechanism, the glottalic airstream mechanism. Here's how it works.
First, the vocal cords completely close so that for a brief moment no air
escapes from the lungs and air is compressed in the throat
(pharynx).
If the closed glottis is raised to push the air up and
outward, an ejective consonant is produced. The air is forced into
the vocal tract and there manipulated by the organs of speech. Compare
glottalized vs. non-glottalized [k] in Georgian. Ejectives are found
in the languages of the Caucasus mountains, among many Native American
languages, and among the Afroasiatic languages of north Africa (Hausa,
Amharic).
If the closed glottis is lowered to create a small
vacuum in the mouth, an implosive consonant is produced. The
lowering glottis acts like the downward movement of a piston to create a brief
rarification of the air in the vocal tract. When the stricture in the
mouth is released air moves into the mouth. Swahili has three
implosives: [b], [d], [g]. Implosives occur mostly in languages of
east Africa, in several Amerindian languages and in some IE languages of
northern India. (Compare the difference between implosives, using the
glottalic airstream mechanism, and ingressives, which use inhaled
air.)
The third and final airstream mechanism used by human language is confined to
certain languages of southwest Africa. It is called the velaric airstream
mechanism. There is regular oral articulation, while the back of
tongue seals off air from the lungs and creates a relative vacuum. Air in
the mouth is rarified by backward and downward movement of the
tongue. When the stricture is released the air rushes in, creating
a click. Although we think of such sounds as exotic, English uses a few
of them for quasi-linguistic sound gestures: 'grandmother's kiss'
(bilabial click), encouraging a horse (lateral click), tisk-tisk (actually a
dental or alveolar click). Some Khoisan languages have over a dozen
clicks. (release of click can be supplemented by additional features:
aspirated, nasal/ non-nasal). One Khoisan language !Xung has 48
different click sounds. A few of the Bantu languages of South Africa, such as
Zulu, have clicks; presumably, these sounds were borrowed from the San
(Bushmen) and Khoikhoi (Hottentot) peoples who originally lived throughout all
southern Africa. Zulu and the other Bantu languages that use clicks
spell them with the letters c, x, q. (cf. the name of the tribe Xhosa).
Notice that clicks stop up the air only in the oral cavity; pulmonic air
continues through the nose (one can produce a nasal hum while producing
clicks).
For the sake of completeness, it should be said that at least one other
airstream mechanism could possibly be used for producing sounds in human
language. A puff of air could be trapped in either cheek, then released
to be manipulated by the speech organs. This is the airstream mechanism
employed by the Walt Disney character Donand Duck and could be called the buccal
airstream mechanism. So far as we know, Donald Duck is unique in
using it. And no language uses a gastric airstream mechanism, which
would be modifying air burped up from the stomach.
The phonation process
The vocal cords can be in one of several positions during the production of a
sound. The muscles of the vocal cords in the glottis can behave in
various ways that affect the sound. The effect of this series of vocal
cord states is called the phonation process.
Voicing. Vocal cords can be narrowed along their
entire length so that they vibrate as the air passes through them. All
English vowels are voiced. Voiceless vowels also occur but are far rarer
than voiceless consonants are much more common than voiceless vowels.
Voiceless vowels usually occur between voiceless consonants, as in Japanese. No
language has only voiceless vowels; a language has either only voiced vowels or
voiced and a few voiceless vowels.
There are also several other vocal cord states that are used to modify sound in
the world's languages. None is used as a regular feature of English.
Laryngealization. The posterior (artenoid) portion of the vocal
cords can be closed to produce a laryngealized or creaky sound. This
doesn't play a meaningful role in English phonology, althoght we might use a
creaky voice to imitate an old witch when reading fairy tales. Some
languages of Southeast Asia and Africa have creaky vowels and consonants, as in
Margi, a Nigerian language: ja to give birth/ laryngealized ja
thigh; or in Lango a Nilotic language: man this/
laryngealized man testicles.
Murmur. The anterior (ligamental) portion of the vocal cords can
be closed, with the vocal cords vibrating. This produces murmured or
breathy sounds. Murmured or breathy vowels occur in some languages of
Southeast Asia. We make murmured sounds to imitate the Darth Vader
voice. In many Indo-European languages of India the stop consonants have
a murmured release; in other words the anterior portion of the vocal
cords remain closed after the stop has been produced during part of the time
the vowel is pronounced: bh, dh, gh, Buddha.
Whisper. A similar vocal cord state is used to produce the whisper.
The vocal chords are narrowed but not vibrated, narrowing is more complete at
the anterior end, less so at the posterior end. Whispered sounds do not
contrast with non-whispered sounds to produce differences of meaning in any
known language, but the whispered voice is common as a speech variant across
languages. There is no IPA symbol for a whispered sound.
The oro-nasal
process
Regardless of which airstream mechanism is used, speech sounds are produced
when the moving air is somehow obstructed within the vocal tract. The
vocal tract consists of three joined cavities: the oral cavity,
the nasal cavity, and the pharyngeal cavity. The surfaces and
boundaries of these cavities are known as the organs of speech.
What happens to the air within these cavities is known as the oro-nasal
process.
Let's talk first about the oro-nasal process in the articulation, or
production, of consonants.
There are two major ways to classify the activity of the speech organs in the
production of consonants: place of articulation and manner of
articulation.
Consonantal
place of articulation
The place of articulation is defined in terms of two articulators These
may be: lips, teeth, alveolar ridge, tongue tip (apex), tongue blade (laminus),
or back of the tongue (dorsum), hard palate, soft palate (velum), uvula,
glottis, pharynx, glottis (the "voice box," or cartilaginous
structure where the vocal cords are housed).
bilabial [b, p, m, w]
labiodental, [f, v]
interdental, [T, D]
(apico)-dental the tip (or apex) of the tongue and the back teeth: Spanish [t,
d, s, z].
alveolar (apico-or lamino-) tongue and alveolar ridge (compare 'ten' vs.
'tenth'). Examples: English [t, d, s, z]
postalveolar or
palatoalveolar (apico- or lamino-) (English [S]/[Z]),
retroflex (apico-palatal) bottom of the tongue tip and palate, or
alveolar ridge: Midwest English word-initial [«] and [t, d, n] in many
Dravidian languages and many languages of Australia.
palatal (apico- or lamino-) (English [j]), [S]/[Z] in many
languages
velar or
dorso-velar Eng. [k, g, N] German [x]
Greek [V]
uvular French [R], also found in many German dialects.
pharyngeal (constriction of the sides of the throat),
glottal (glottal stop, the vocal chords are the two articulators. cf. A-ha, bottle,
Cockney English 'ave). [h] is a glottalic fricative sound.
Manner of
articulation
Now let's look at the ways that moving air can be
blocked and modified by various speech organs. There are several methods
of modifying air when producing a consonant, and these methods are called manners
of articulation. We have already examined where the air is blocked.
Now let's look at how the air can be blocked.
1)
Sounds that completely stop
the stream of exhaled air are called plosives: [d], [t], [b], [p],
and [g], [k], glottal stop. Another word for plosive is stop (nasals are
also stops, however, since the air is stopped in the oral cavity during their
production).
2)
Sound produced by a near
complete stoppage of air are called fricatives: [s], [z], [f], [v], [T],
[D], [x], [V], [h], pharyngeals.
3)
Sometimes a plosive and a
fricative will occur together as a single, composite sound called an affricate:
[tS], [ts], [dz], [dZ], [pf].
4)
All other types of continuant
are produced by relatively slight constriction of the oral cavity and are
called approximants. Approximants are those sounds that do not
show the same high degree of constriction as fricatives but are more
constricted than are vowels. During the production of an approximant, the air
flow is smooth rather than turbulent.
There
are four types of approximants.
a)
The glottis is slightly
constricted to produce [h], a glottalic approximant.
b)
If slight stricture occurs
between the roof of the mouth and the tongue a palatal glide is produced
[j]. If the constriction is between the two lips, a labiovelar
glide is produced. The glides [j] and [w] are also called semivowels,
since they are close to vowels in degree of blockage.
c)
If the stricture is in the
middle of the mouth, and the air flows out around the sides of the tongue, a lateral
is produced. Laterals, or lateral approximants, are the various
l-sounds that occur in language. In terms of phonetic features, l-sounds
are + lateral, while all other sounds are + central.
d)
The third type of approximant
includes any of the various R-sounds that are not characterized by a
flapping or trilling: alveolar and retroflex approximants. This includes
the American English r (symbolized in the IPA by an upside down [®], but we
will use the symbol [r]).
It the air flow is obstructed only for a brief moment by the touch of the
tongue tip against the teeth or alveolar ridge, a tap, or tapped [|] is
produced: cf. Am Engl ladder; British Engl. very.
If the tongue tip is actually set in motion by the flow of air so that is
vibrates once, a flap or flapped r is produced: this is the sound
of the Spanish single r. Flaps can even be labio-dental, as in one
African language, Margi, spoken in Northern Nigeria.
If the air flow is set into turbulence several times
in quick succession, a trill is produced. Trills may be alveolar,
produced by the apex of the tongue: the Spanish double rr perro; the
French uvular [R]: de rien; Bilabial trills [B] have been found to occur
in two languages of New Guinea: mBulei = rat in
Titan.
Degree of blockage
In discussing manner of articulation, it is also relevant to classify
consonants according to the total degree of blockage. Remember that all sounds
that involve significant stoppage of air in the vocal tract are known as consonants
(this distinguishes them from vowel, which are produced by very little blockage
of the airstream). Consonants differ in the manner as well as the degree
to which the airstream is blocked. While we are discussing the manner in which
air is blocked, we can also classify sounds as to the degree of blockage.
Plosives, fricatives, and affricates are all sounds made by nearly complete or
complete blockage of the airstream. For this reason they are known
collectively as obstruents.
Consonants produced by less blockage of the airstream are called sonorants.
With little blockage the airstream flows out smoothly, with relatively little
turbulence. There are several types of sonorants, depending upon where
the airstream is blocked in the vocal tract and how air flows around the
impediment.
Sonorants are produced using the following manners of articulation:
1) Sounds produced by stoppage at the vocal tract and release through the nose
are called nasals. The nasals [m], [n], and [ng] have the same
point of articulation as the plosives [d], [b], and [g], except that the
velum rises and air passes freely through the nose during their production; the
oral stoppage is not released. Plosives are also known as oral stops,
to distinguish them from the nasal stops. All known languages have
at least one nasal except for several Salishan languages spoken around the
Puget Sound (including Snohomish)
The division of consonants into obstruents and sonorants is not absolute.
In some languages, such as Russian, the glide [j] is produced by much more
blockage and could almost as easily be called a fricative.
Also,
some l- and r- sounds are definitely fricatives rather than approximants.
Some types of l- and r-sounds are characterized by a highly turbulent flow of
air over the tongue, even more than for the trilled [r]. In Czech, besides the
regular flapped r, there is a strident trilled and tensed [r] which is much
more like an obstruent than a sonorant. Navaho has a fricative [tl] which is
definitely more fricative than approximant.
Because all l- and r- sounds (whether approximant and non-approximant) are
produced in the same way--with the the air flowing around or over the tongue
like water moving around a solid object--there is a collective term for these
sounds: liquids. Liquids and nasals are sometimes able to carry a
syllable. Syllabic r and l occur in Czech and Slovak: StrC prst
skrz krk. The IPA uses a dot beneath them to signify syllabicity.
Review of some
articulatory terminology
ü
Stops
(air completely blocked in the oral cavity)-nasal and oral (plosives).
ü
Obstruents (high degree of blockage) include: plosives, fricatives, and
affricates.
ü
Sonorants (low degree of blockage)include: nasals and approximants.
ü
Approximants (the lowest degree of blockage) include: the glottal approximant [h],
the glides [j] and [w], and most l- and r-sounds.
ü
Liquid:
all l- and r- sounds, whether fricative or approximant.
Go over the
handout on the English sound system (up to the vowel questions)
Secondary
articulation features in consonants
Lack of release. Plosives may not be released fully when pronounced at the end of
words. This occurs with English [p} b}, t}, d}, k}, g}]
Length. Consonants may be relatively long or short. Long
consonants and vowels are common throughout the world, cf. Finnish, Russian:
zhech/szhech to burn; Italian: pizza, spaghetti.
Long or double consonants are also known as geminate consonants and are
indicated in the IPA by the symbol […]. Geminate plosives and affricates
are also known as delayed release consonants.
Nasal
release. In certain African languages: [dn].
Ø
Palatalization. Concomitant raising of the blade of the tongue toward the
palate: cannon/canyon, do/dew; common among the sounds of
Russian and other East-European languages: mat/mat' luk/lyuk.
There are thousands of such doublets in Russian.
Ø
Labialization. Concomitant lip rounding cf. sh in shoe vs. she (IPA
uses a superscript w to transcribe labialization) In some languages of Africa
the constrast between labialized and non-labialized sounds signal differences
in meaning, as in Twi: ofa´ he finds/ ofwa´ snail.
Ø
Velarization. The dorsum of the tongue is raised slightly.
Compare the l in wall, all (velarized or dark l) vs. like, land
(continental or light l). The glide [w] is also slightly velarized. In
Russian all non-palatalized consonants are velarized.
Ø
Pharyngealization. Concomitant constriction of throat. Afroasiatic languages of
north Africa, such as Berber: zurn they are fat/ zghurn they
made a pilgrimage.
Ø
Tensing. The muscles of the articulators can be or lax when pronouncing
a sound. Cf. Korean stops: Lax unvoiced p, lax voiced b, tense
unvoiced pp. Tensing also occurs in the vocal cords during the production
of tensed stops, so tenseness could also have been listed under phonation
processes.
The oro-nasal
process in vowels
Go over part D
on the handout now; go over part E during the lecture on vowels.
Sounds produced by no blockage other than a slight raising of the tongue or a
narrowing of the lips are called vowels. Vowels differ in several
phonetic features. Three are most important.
1)
which part of the tongue is raised:
front/central/back (mention the difference between the [a] of father in English
dialects.)
2)
how high the tongue is
raised: high, middle, low
3)
whether or not the lips are
rounded. Several other features distinguish vowels on a more limited basis
across the world's languages.
4)
whether or not the tongue is tense
(bunched up; in English, diphthongalized) or lax (relaxed and slightly shorter,
closer to the center of the oral cavity). In English, stressed lax
vowels only occur in closed syllables, tense vowels occur in either open or
closed syllables:
Tense=
by, too, way, so, ma
Lax=
bit, but, full, get, oil/or, and,
(also, hard, in New England pronunciation), as well as schwa: sofa
5)
nasal vs. non-nasal (describe the
velum and oro-nasal process)
6)
long vs. short. Many
languages have a distinction between short and long vowels: Hawaiian,
Navajo, etc. Estonian has three vowel lengths; in English vowels
are slightly longer before voiced consonants and slightly shorter before
voiceless.
7)
Different phonation processes
involving the vocal cords produce several featural contrasts in vowels as in
consonants: voiced/voiceless (whispered) laryngealized (creaky),
murmured (breathy).
There
are three diphthongs in General American English
[aU] house
[aI]
like, [OI] oil, boy, toy
Diphthongs
in other American dialects.
2.4 Auditory phonetics
It is
concerned with speech perception, principally how the brain forms perceptual
representations of the input it receives. Basicly, it focus on listener´s
ear and listener´s brain.
THE
EAR:
The ear
is divided into three different parts:
1.- THE OUTER
EAR.
2.- THE
MIDDLE EAR.
3.- THE
INNER EAR.
1.
THE OUTER EAR:
The
only visible part of the ear is the pinna (the auricle) which
- with its special helical shape - is the first part of the ear that reacts
with sound. The pinna acts as a kind of funnel which assists in directing the
sound further into the ear. Without this funnel the sound waves would take a
more direct route into the auditory canal. This would be both difficult and
wasteful as much of the sound would be lost making it harder to hear and
understand the sounds.
The
pinna is essential due to the difference in pressure inside and outside the
ear. The resistance of the air is higher inside the ear than outside because
the air inside the ear is compressed and thus under greater pressure.
In
order for the sound waves to enter the ear in the best possible way the
resistance must not be too high. This is where the pinna helps by overcoming
the difference in pressure inside and outside the ear. The pinna functions as a
kind of intermediate link which makes the transition smoother and less brutal
allowing more sound to pass into the auditory canal (meatus). Once the sound waves have passed the pinna,
they move two to three centimetres into the auditory canal before hitting the
eardrum, also known as the tympanic membrane.
The eardrum
(tympanic membrane), which marks the beginning of the middle ear, is extremely
sensitive. In order to protect the eardrum, the auditory canal is slightly
curved making it more difficult for insects, for example, to reach the eardrum.
At the same time, earwax (cerumen) in the auditory canal also helps to keep
unwanted materials like dirt, dust and insects out of the ear.
In
addition to protecting the eardrum, the auditory canal also functions as a
natural hearing aid which automatically amplifies low and less penetrating
sounds of the human voice. In this way the ear compensates for some of the
weaknesses of the human voice, and makes it easier to hear and understand
ordinary conversation.
2.- the
middle ear:
Three
bones
The
eardrum is very thin, measures approximately 8-10 mm in diameter and is
stretched by means of small muscles.
The
pressure from sound waves makes the eardrum vibrate. The vibrations are
transmitted further into the ear via three bones: the hammer (malleus), the
anvil (incus) and the stirrup (stapes). These three bones form a kind of
bridge, and the stirrup, which is the last bone that sounds reach, is connected
to the oval window. The oval window is a
membrane covering the entrance to the cochlea in the inner ear. When the
eardrum vibrates, the sound waves travel via the hammer and anvil to the
stirrup and then on to the oval window.
When
the sound waves are transmitted from the eardrum to the oval window, the middle
ear is functioning as an acoustic transformer amplifying the sound waves before
they move on into the inner ear. The pressure of the sound waves on the oval
window is some 20 times higher than on the eardrum. The pressure is increased
due to the difference in size between the relatively large surface of the
eardrum and the smaller surface of the oval window. The same principle applies
when a person wearing a shoe with a sharp stiletto heel steps on your foot: The
small surface of the heel causes much more pain than a flat shoe with a larger
surface would.
The
Eustachian tube
The
Eustachian tube is also found in the middle ear, and connects the ear with the
rearmost part of the palate. The Eustachian tube equalises the air pressure on
both sides of the eardrum, ensuring that pressure does not build up in the ear.
The tube opens when you swallow, thus equalising the air pressure inside and
outside the ear.
In most cases the pressure is equalised automatically,
but if this does not occur, it can be brought about by making an energetic swallowing
action. The swallowing action will force the tube connecting the palate with
the ear to open, thus equalising the pressure.
Built-up
pressure in the ear may occur in situations where the pressure on the inside of
the eardrum is different from that on the outside of the eardrum. If the
pressure is not equalised, a pressure will build up on the eardrum, preventing
it from vibrating properly. The limited vibration results in a slight reduction
in hearing ability. A large difference in pressure will cause discomfort and
even slight pain. Built-up pressure in the ear will often occur in situations
where the pressure keeps changing, for example when flying or driving in
mountainous areas.
3.- The inner
ear:
Once
the vibrations of the eardrum have been transmitted to the oval window, the
sound waves continue their journey into the inner ear. The inner
ear is a maze of tubes and passages, referred to as the labyrinth. In the
labyrinth can be found the vestibular and the cochlea.
The
cochlea
In
the cochlea, sound waves are transformed into electrical impulses which are
sent on to the brain. The brain then translates the impulses into sounds that
we know and understand.
The cochlea resembles a snail shell or a wound-up
hose. The cochlea is filled with a fluid called perilymph and contains two
closely positioned membranes. These membranes form a type of partition wall in
the cochlea. However, in order for the fluid to move freely in the cochlea from
one side of the partition wall to the other, the wall has a little hole in it
(the helicotrema). This hole is necessary, in ensuring that the vibrations from
the oval window are transmitted to all the fluid in the cochlea.
When
the fluid moves inside the cochlea, thousands of microscopic hair fibres inside
the partition wall are put into motion. There are approximately 24,000 of these
hair fibres, arranged in four long rows.
The
hair fibres are all connected to the auditory nerve and, depending on the
nature of the movements in the cochlear fluid, different hair fibres are put
into motion.
When
the hair fibres move they send electrical signals to the auditory nerve which
is connected to the auditory centre of the brain. In the brain the electrical
impulses are translated into sounds which we recognise and understand. As a
consequence, these hair fibres are essential to our hearing ability. Should
these hair fibres become damaged, then our hearing ability will deteriorate.
Another
important part of the inner ear is the organ of equilibrium, the vestibular.
The vestibular
The
vestibular registers the body's movements, thus ensuring that we can keep our
balance. The
vestibular consists of three ring-shaped passages, oriented in three different
planes. All three passages are filled with fluid that moves in accordance with
the body's movements. In addition to the fluid, these passages also contain
thousands of hair fibres which react to the movement of the fluid sending
little impulses to the brain. The brain then decodes these impulses which are
used to help the body keep its balance
THE BRAIN:
How the brain filters noise:
Our left side of the brain
is more active when we discriminate relevant sounds from background noise,
according to the findings of a study by an international team of scientists.
A night out is often a frustrating experience for
hearing impaired people. They find the words of their conversation partners
drowned out by the conversations of others, music or street noise. They lack
the so-called cocktail party ability of people with normal hearing to separate
relevant sounds from background noise.
Left side of brain sorts
out the sounds
Brain researchers have investigated what happens in
the brain when discriminating between the sounds we listen for and other noise.
The study was headed by Hideko Okamoto of the University of Münster, Germany.
He and his team exposed a number of individuals to test sounds and background
noise in one or both ears while monitoring their brain activity. The recorded
brain activity indicated greater activity in the left half of the brain when
discriminating sounds from noise. In other words, the cocktail party effect
occurs in the left side of the brain.
As of yet, the researchers are unable to determine why
hearing impaired people’s ability to discriminate sounds from noise is
diminished. This is a matter for future research. Knowledge about the brain functions will eventually benefit hearing
impaired people in terms of the development of new treatment methods and
assistive devices.
Source: BMC Biology
2.3 The organ of speech
It
is necessary that the student of phonetics should have a fairly clear idea of
the structure of the functions of the organs of speech. Those who have not
already done so should make a thorough examination of the inside of the mouth by
means of a hand looking-glass. The best
way of doing this is to stand with the
back to the light and to hold the looking- glass in such a position thatv it
reflects the light into the mouth and at the same time enables the observer to see in the glass in the
interior thus illuminated. It is not difficult to find the right position for
the glass.
Models
of the organs of speech will be found useful. Suitable models of section of the
head, mouth, nose, larynx, etc. may be obtained from dealers in medical instruments.
Figs. 1.and 2 show all that is essential for the present book. A detail description of the various parts is
not necessary the following points should, hoever, be noted.
The
roof of the mounth is devided, for the purpose of phonetics, into three parts
called the teeth-ridge, and the soft palate. The teeth-ridge in defined as part
of the roof mouth just behind the teeth which is covex to the tongue, the
devision between the teeth-ridge and the palate being defined as the tongue and
begins to be concave. The remainder of
the roof of the mouth comprises the other two parts, the front part
constituting the hard palate, and the back part the soft palate. These two
parts should be examined carefully in the looking-glass they may be felt with
the tongue or with the finger. The soft palate can be moved upwards from the
position shown in fig. 1, and when raised to its fullest extent it touches the
back wall of the pharynx as show in fig.10, etc.
The
pharynx is the cavity situated in the throat immediately behind the mouth.
Below it is the larynx which forms the upper part of the windpipe (the passage)
leading of the lungs). The epiglottis is a sort of tongue situated just above
the larynx. It is probably contracted in such a way as to protect the larynx during
the action of swallowing, but it does not appear to the enter into the
formation of any speech-sound .
For the purposes of the
phonetics it is convenient to imagine the surface of the tangue divided into
three parts. The parts which normally lies opposite the soft palate is called
the front and the part which normally lies opposite the teeth-ridge is called
blade. The extremity of the tongue is called the tip or point, and is included
in the blade. The definition of ‘back’ and ‘front’.
The
tongue is extremely mobile. Thus the tip can be made to touch any parts of the
roof of the mouth from the teeth to the
beginning of the soft palate. The other parts of the tongue may likewise be
made to articulate against different parts of the roof the month. Moreover it is possible to spread out the
fore of the tongue laterally ( after the
manner shown in fig.) the presence or absence f the such lateral contraction is
probably immaterial for most sounds, but there are a few in which lateral
contraction appears to play an essential
part.
The vocal card are
situated in the larynx the resemble two
lips . the run in a horizontal direction from the back to front.
The space between them is called the glottis. The cords may be kept
apart or the may be brought near together so as to touch and thus close the air
passage completely. When they are
brought near together and air is forced between them, they are brought near
together and air is forced between them, they vibrate, producing a musical
sound.
In
the larynx just above the vocal cords is situated another pair lips somewhat
resembling the vocal cords and running parallel to them. These are known as the
false vocal cards.
Chapter III
3.1 Coclution
Phonetics is
one important of learning. Cause phonetics explain how the sound production, to transfer, and
accept the sound. We actually make much finer
discriminations among sounds, but English only requires 40. The other
discriminations are what lets us detect the differences in accents and dialects,
identify individuals, and differentiate tiny nuances of speech that indicate
things beyond the obvious meanings of the words. Within british English and American English there are also a variety of
accent some of them have received more attention than others from phoneticians
and phonologists. These are received pronountation (RP) and general american.
Daftar pustaka
4. an outline of
English Phonetics,Jones,Daniel.5th edition,1983
