Linguistic Development Research Paper (Page 15 of 37) in pdf

4 WHAT IS IT THAT DEVELOPS?

The tongue is the organ of articulation most involved in the production of speech sounds. It is

involved with the production of all of the vowel sounds, and the majority of the consonants. The

great mobility of the tongue is due to the arrangement of muscles in all three planes, to allow great

control, of size, shape, movement and position. Seven basic types of tongue movement are possible

allowing the tip, edges and center a fair degree of independent movement.

The soft palate (or velum or velo-pharyngeal sphincter ) is the extension of the hard palate, at the

back of the mouth. Muscles allow it to be raised and lowered during speech. It determines whether

air is allowed to pass through the nasal cavity and is thus involved in the production of many sounds

such as /n/ and /m/.

4.1.4

Auditory Reception

The ﬁrst step in the reception and decoding of signals is in the ear. The ear is nominally divided

into three sections: the inner, middle and outer ear.

The outer, visible part of the ear known as the “auricle” or “pinna”, and the narrow passage that

leads to the ear drum known as the “external auditory canal” is non-mobile and consists mostly of

cartilage. It plays a minor part in the language process, mainly being involved in the focusing of

sound waves into the ear, and assisting in the localization of sound waves. It is about 2.5 cm long

and ends at the eardrum. It contains hairs and glands that secrete wax. It also acts as an ampliﬁer

for frequencies between 3000 and 4000 Hz.

The outer ear is separated from the middle ear by the eardrum (or timpanic membrane) It lies at

an angle of 55 degrees across the canal, and is thus roughly circular in shape. It is made of a tough,

ﬁbrous, elastic tissue that is able to resonate in response to sound waves reaching it. The shape of

the membrane forces the vibrations to be focused on a prominence near its middle. The prominence

passes the vibrations on to the ﬁrst of the small bones in the middle ear, attached to the other side

of the membrane.

The cavity behind the eardrum, known as the timpanic cavity is ﬁlled with air. It has a direct

passage to the nose and throat via the Eustachian tube. The middle ear turns sound vibrations into

mechanical movement of the three bones of the middle ear known as “ossicles”. The purpose of

having such bones in the middle ear is that the leverage system employed by the bones ampliﬁes the

vibrations by 35 times. Such ampliﬁcation is necessary because the inner ear is ﬁlled with a viscous

ﬂuid that would be insensitive to lesser vibrations.

The inner ear is a small series of interconnected cavities – the “Aural Labyrinth”. It has two parts -

the semicircular canals (“Vestibular Canals”) that are organized so that the loops are set at angles

to each other. These are used to control the sense of balance. They are ﬁlled with ﬂuid and hairs

to detect the movement of the ﬂuid in response to the motion of the head.

The other part of the inner ear known as the “Cochlea” is a coiled cavity resembling a shell. It

is 35mm in length and coiled 2

times. Its primary function is to turn mechanical vibrations in

the middle ear into nerve impulses capable of being transmitted to the brain. The Cochlea tapers

during is spiral, thus allowing responsiveness to diﬀerent frequencies, over the course of the taper.

Within the cochlea lies a highly sensitive organ of hearing based upon similar principles to that of

the vestibular canals. It contains an arrangement of cells with very ﬁne hairs distributed in rows and

layers along a membrane. These hair cells are able to pick up the pressure movements of the ﬂuid

in the inner ear. The cells connect to nerve cells which carry impulses along the cranial (auditory)

nerve. the messages thus are carried to the brain.

Linguistic Development Research Paper Page 15

Related Articles

Related forms

Related Categories