Distinctive Features of Sounds
The Speech, the voice is a continuous sound, whose shaping and articulation is the result of precise and unwell-known operations.
The majority of the sounds of the language are the fact of the passage of a column of air coming from the lungs, which passes through one or more resonators of the phonatory apparatus.
The main resonators are:
The Pharynx:
Or pharyngeal cavity is a musculo-membranous conduct located between the mouth and the esophagus on the one hand
and between the nasal fossae and the larynx on the other hand.
The wall of the pharynx is constituted by constrictor muscles, the action of which causes a modification of the diameter of the pharynx.
The root of the tongue can also act as a constrictor, by retreating or advancing,
it acts on the volume of this supraglottic cavity.
The Nasal Cavities:
The nasal cavities are two calvities separated by a median vertical partition covered with mucosa.
They contribute to the amplification of the sound by the resonance effect of the cavities.
The mouth:
Or oral cavity is separated from the nasal cavities by a partition called the Palate.
In this cavity are articulators, some fixes (called passive) like the hard palate
or the incisor papillae,
others moving(called active), such as the uvula
or the soft palate
The Labial Cavity:
The Cavity created when the lips are projectedforward:
it's the labial protrusion.
Production of sound by the phonatory apparatus
.... and characteristics of the sound emitted.
Speech is a succession of sonorous events that alternately produce a so-called voiced sounds
characterized by the vibration of vocal cords
and unvoiced sounds that do not involve the vocal cords.
The voiced signal is a pseudo-periodic signal having more or less important frequency zones.
These maximum envelope frequential zones are called formants.
The spectrum of the sound emitted by the vocal cords is modulated by the resonant properties of the resonator body
and by the position of the lips.
The various possible modifications in the resonator body for the sound treatment create the possibility to obtain an extremely important panel of sounds!
Sound Production Mechanisms
The mechanisms of production:
# Step 1
Formation of the airflow, through the subglottal organs, and in particular the lungs, pushed by the diaphragm.
The latter contracts, which expels the air from the lungs and it is this air whose variations in pressure at the level of the pharynx will create the sound.
# Step 2
Creation of the sound at the vocal chords or Phonation level.
The air expelled from the lungs reaches the level of the vocal cords at rest.
The strings are closed(apnea phase).
The air accumulates there until the pressure exerted by the column of air is too high.
The air pressure exerted on the vocal cordsis high enough to keep them apart.
The air begins to escape through the opening.
The velocity of this fluid then increases, resulting by a "drop" in the subglottic pressure
The lower part of the vocal cords then begin to close.
The vocal cords are closed in an evolutionary manner.
Their structure is indeed quite complex.
The lower part closes almost immediately!
This closure causes a sudden drop in pressure to the upper level, which closes in a snap.
The air will again accumulate under the vocal cords, and the process begins again!
Characteristics of the sound produced by the vocal cords
The air circulates in a jerky way in the vocal tract, which generates an acoustic vibration similar to the clapping of hands, when we applaudes!
This sound is a rather complex sound, consisting of a fundamental frequency(which corresponds to the average fréquence of the movement of the vocal cords), and its harmonics.
It is by contraction of different muscles of the larynx (thyro-arytenoid, lateralcrico- arytenoid, posterior crico-arytenoid and crico-thyroid)
that the contraction of the vocal cords and thus the sound emitted will change.
In fact, the phonatory apparatus contains two sound sources:
# A quasi-periodic source:
The vocal cords in vibration.
#A noise source:
Turbulent flows produced by an obstruction of the passage of air in the vocal tract.
The height of the sound emitted depends on the frequency of the vibrations.
Its intensity depends in principle on the amplitude of the vibrations, determined by the size of the air flow through the glottis,
but also by the degree of closure of the glottis for each vibration.
If the closing remains incomplete and a part of the air flow passes without being transformed into vibrations, the soundbecomes weaker.
Height and intensity are also dependent on the tension of the vocal cords.
The female voices are sharper than the male voices because of the length of the vocal cords.
It is generally accepted that the long vocal cords correspond rather to deep or "grave" voices, and the short vocal cords to the shrill voices.
The men have vocal chords of 17 mm (tenor voice) to 24 mm (bass voice) and women of 14 mm (soprano voice) to 18mm (voice of contralto).
Formatting the Sound
Physical Reminder on the phenomenon
Of Resonance:
Let us recall that the phenomenon of resonance consists
in a modification of the timbre of the sound resulting from the enrichment of some of its harmonics and the impoverishment of others.
Each cavity, by its shape, has a characteristic frequency or its own frequency.
This eigenmode may be excited by a fundamental sound or one of its harmonics, and the cavity then resonates under the influence of this sound and reinforces it.
The characteristic frequences varies according to the shape and volume of the cavities, the larger ones generally having a cleaner sound than the smaller ones.
So each cavity has its own resonance, each anatomical structure is unique!
Each Being has its own frequencies its own sound boxes, an exclusive, unique sound.
Changes in shape and volume therefore allow agreement with sounds of very different frequencies:
The articulators form cavities in the vocal tract, the resonant frequencies of which determine the shape of the spectrum emitted.
Moreover, two resonant cavities open to each other modify their reciprocal properties
in particular by modifying their characteristic frequency, the sharper becomes even more acute.
We are talking about a coupling phenomenon.
This stage corresponds to the amplification and to the frequency filtering of the source wave produced by the glottis.
These functions are taken up in a complex way by the supra glottic organs.
These members can be grouped into four resonators which reinforce or atenuates certain frequencies.
These resonators are cavities of varying shape and size, which makes it possible to adjust the timbre of the sound, via the phenomenon of resonance.
Resonances in the phonatory apparatus
The pharynx does not change easily, but its length may change slightly by raising or lowering the larynx on one side, or the veilof the palate on the other side.
The latter also acts as a valve which makes it possible to isolate or connect the nasal cavity to the pharynx.
The epiglottis also acts as a valve, whose function is to prevent all food from reaching the larynx.
It is open during normal breathing but closes at the time of swallowing.
The nasal cavity also has dimensions and a fixed shape.
The oral or buccal cavity is the most important part of the vocal tract because its shape and size can vary by adjusting the relative positions of the palate, tongue, lips, and teeth.
Notions of Phonetics
In linguistics, a phoneme is the smallest distinctive unit(that is to distinguish words from each other) that can be isolated in the spoken chain.
Traditional phonetics classifies phonemes into vowels, consonants and semi- vowels(or semi-consonants).
If the passage of air is made freely from the glottis, we have to deal with a vowel.
If the passage of air from the glottis is obstructed, completely or partially, in one or more places, we are dealing with
a consonant.
The semi-vowels present the same articulation as the vowels, but behaves in the syllable like the consonants,
as this one can not constitute by themselves a syllable, when the vowels, yes!
The vowels
The major characteristic of vowels is the free passage of air from supraglottic cavities.
The only treatment that air can undergo is resonance, ie the reinforcement of certain bands of frequencies.
The timbre of a vowel will depend on the variation of the following elements:
#The number of resonators resonated (buccal, labial and nasal);
#The shape of the buccal resonator;
#The volume of the buccal resonator.
The number of resonators is always at least one, since the buccal resonator is always present!
If the veil of the palate is raised, the air does not pass through the nasal resonator, but spreads exclusively in the buccal resonator;
If the veil of the palate is lowered, the air passes simultaneously through the buccal and nasal resonators, bringing the number of resonators to at least two.
If the lips are projected forward and rounded, a third resonator is formed at the buccal outlet, the labial resonator;
If, on the contrary, the lips are applied against the teeth, the labial resonator is not formed.
Thus, one opposes:
# Nasal vowels(presence of the nasal resonator) to oral vowels.
# Rounded vowels(presence of labial resonator) to non-rounded vowels.
Classification of Vowels
Within the category of vowels, the classification is made according to:
#Nasality (oral or nasal vowels);
#The aperture or opening of the vocal tract, which depends on the elevation of the tongue in relation to the arch of the palate(closed or open vowels);
The articulation zone, determined by the position of the dome of the tongue in the buccal cavity(anterior or posterior vowels);
#The shape of the lips(vowel rounded or not rounded)
The systematic use of these criteria makes it possible to define the cardinal (oral) vowels whose vocalic triangle provides a schematic representation.
Consonants and semi-vowels
The consonants differ from the vowels by the presence of an obstacle which prevents the free flow of air.
The quality of this obstacle, or mode of articulation, is the main criterion that makes it possible to distinguish between them.
The second criterion of classification is the position of this obstacle, or point of articulation.
Articulation Mode
In articulatory phonetics, the mode of articulation of a consonant designates a set of properties of its articulation that modify the nature of the exhaled air current.
There are two major modes of consonantal articulation:
#The passage of the air is closed (momentary occlusion of the expiratory channel)and the sound results from its sudden opening;
We have then an occlusive consonants.
Occlusive consonants are "noisy" sounds of short duration, characterized by a silence coming from the complete closing of the vocal tract at a precise point.
#The passage shrinks but is not interrupted; In this case we speak of continuous or constrictive consonants, of which the fricatives are the most representative;
The fricative consonants are noisy sounds produced by the turbulent flow of air,
When this flow encounters a narrowing, a place of constriction, a friction noise is produced.
Characteristics of the obstacle
The two main modes of articulation(occlusion and constriction)are often specified by an additional adjective, characterizing the obstacle.
Depending on the type of flow, the central consonants and the lateral consonants are distinguished:
A central consonant is a consonant whose mode of articulation requires for its realization the flow of the air through the center of the mouth above the tongue.
This is the case with almost all consonant in english!
#A lateral consonant is a consonant that requires the air to flow through a lateralcanal (sometimes bilaterally) formed by the collapse of the front of the tongue and the contact of its back with the palate, aircontinuing to escape to the sides of the tongue.
There is only one lateral consonant, the "l" in English.
@ If the obstacle is made intermittent by the beating of the tip of the tongue, we speak of consonants as expected, like the Spanish "r" of "perro".
It is also possible to characterize the mechanism at the origin of the flow:
Pulmonary or non-pulmonary consonants; Injective, ejectives or clicks.
Oral consonants are distinguished from nasal consonants, depending on the resonance cavity used.
English has the following nasal consonants:
# Bilabial: "m" of "mastering";
# Dental: "n" of "november";
#Palatale: endangered,"gn" as in the word "gnangnan" in french!
#Velaire: sounding "ing" as in the word "parking" in english!
@ Finally, all these consonants can be sounded(or voiced) or deaf(or unvoiced) depending on whether the vocal cords areinvolved in their production.
Thus, the consonants whose articulation involves the vibration of the vocal cordsunder the pressure of the air expelled from the lungs are called "consonant sounded" or voiced;
And a consonant whose articulation does not involve the vibration of the vocal cords under the pressure of the air expelled from the lungs is called a "deaf consonant" or an unvoiced consonant.
In English, here are some couples in which the voiced consonants are opposed to their deaf counterparts:
/D/ /t/ for "done" and "trust"
/G/ /k/ for "great" and "color"
/B/ /p/ for "baby" and "profesional"
/V/ /f/ for "victory" and "franck"
/Z/ /s/ for "base" and "bass"
/J/ /ch/ for "just" and "shower".