Articulatory aspect of sounds

The act of speech is the effect which results from the coordinated work of different organs: the lungs, the bronchi, the trachea, the larynx, the vocal cords, or vocal folds (in the trachea), the pharynx, the mouth; the speech organs in the oral cavity, or the mouth cavity, – the tongue (its main parts are the tip, the blade, the front, the back of the tongue); the lower and upper teeth, the alveolar ridge, the hard and the soft palate, the uvula: the lower and the upper lips, the lower jaw; the nasal cavity. The stream of air escapes from the lungs and passes along the vocal tract – the larynx, the pharynx, the oral or nasal cavity. The air pressure below the vocal cords make them vibrate. Vibrations are transmitted by the stream of air, reach the human ear, carried to the brain and perceived by a person as voice. The process of voice production is called phonation. Due to their coordinated movements and particular positions, the human speech organs can produce different sound effects. This process is called articulation. For each sound, the position of the speech organs is changed; consequently, the shape and the size of the pharynx and the oral cavity are changed; as a result, we pronounce different speech sounds.

5 Speech sound as a physical (acoustic) phenomenon

ACOUSTIC ASPECT OF SPEECH SOUNDS

Speech sounds have a number of physical properties, the first of them is frequency, i.e. the number of vibrations per second. The vocal cords vibrate along the whole of their length, producing fundamental frequency, and along the varying portions of their length, producing overtones, or harmonics. When the vibrations pro­duced by the vocal cords are regular they produce the acoustic impression of voice or musical tone. When they are irregular noise is produced. When there is a combination of tone and noise, either noise or tone prevails. When tone prevails over noise sonorants are produced. When noise prevails over tone voiced consonants are produced. The complex range of frequencies which make up the quality of a sound is known as the acoustic spectrum.

When the vibrations pro­duced by the vocal cords are regular they produce the acoustic impression of voice or musical tone. When they are irregular noise is produced. When there is a combination of tone and noise, either noise or tone prevails. When tone prevails over noise sonorants are produced. When noise prevails over tone voiced consonants are produced.

Perception of the pitch of a speech sound depends upon the fre­quency of vibration of the vocal cords. The higher the pitch of vibra­tions, the higher the pitch level. A male voice may have an average pitch level of about 150 cps.1 and a female voice—a level of about 240 cps. The total range of a speaking voice varies from 80 to 350 cps. but the human ear perceives frequencies from 15 cps. to about 20,000 cps. The frequency of sound depends on certain physical properties of the vibrator, such as mass, length and tension.','

The second physical property of sound is intensity. Changes in intensity are perceived as variation in the loudness of a sound. The greater the amplitude of vibration, the greater the intensity of a sound; the greater the pressure on the ear-drums, the louder the sound. Intensity is measured in decibels (dbs).

Any sound has duration, it is its length or quantity of time during which the same vibratory motion, the same pattern of vibration, are; maintained. The duration of speech sounds is usually measured im milliseconds (msecs).

The acoustics of speech is a physical process of transmission of sound through the air. Though the human brain identifies sounds of speech in terms of auditory qualities (physiology and psychology) rather than acoustic properties (physics). That is why the outline of speech acoustics in the following paragraph is provided with reference to the auditory aspect of speech. The acoustics of speech studies the physical properties of air waves produced through movements of the vocal organs, especially through vibrations of the vocal folds. These properties are frequency, amplitude, intensify, duration spectrum. Frequency is the number of movements of air particles per second measured in hertz. The basic frequency is called the fundamental frequency (Fo). On the auditory level, frequency of a pure tone is perceived as pitch; the higher the frequency of a sound, the higher pitch the human brain perceives. Complex tones are a combination of several tones which result from simultaneous vibrations of different organs. Amplitude is the distance between the rest point and the top or bottom point of a wave within which air particles move. Amplitude affects a sound’s intensity. The latter is the chief factor in creating the auditory effect of loudness; the other factors are frequency and duration. Spectrum is correlation between the frequency and amplitude of a sound. The peaks of amplitude in correlation with particular frequencies are the main points of energy in sound production; they are called formants.

7. PSYCHOLOGICAL MECHANISM OF THE SPEECH PROCESS
The psychological mechanism selects from the great amount of acoustic information only linguistically important and interprets it according to the given language system.
Do you know why Russian/Ukrainian students seldom distinguish the sounds [æ]
and [e] like in "bad - bed"? It happens because this linguistic information is not important for their mother tongue. That is why you can often hear students pronounce "bed news" or "bed weather".
The same happens when they devoice final consonants at the end of the words, e.g. He took his pen out of his back (instead of bag).
She was hungry and wanted to buy some foot (instead of food).

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