Speech and Speech Disorders

I

Introduction

Speech and Speech Disorders. Speech is a learned system of communication requiring the coordinated use of voice, articulation, and language skills. Although many animals are physiologically able to use the voice for communicating a wide range of simple messages to others of their species, only humans are able to produce true speech (as opposed to the skills in speech mimicry of such birds as parrots and mynae). In a broad sense, speech is synonymous with language.

II

Voice

Voice, or phonation, is the sound produced by the expiration of air through vibrating vocal cords (see Larynx). Voice is defined in terms of pitch, quality, and intensity, or loudness. Optimum pitch, which means the most appropriate pitch for speaking, varies with each individual. Both optimum pitch and range of pitch are fundamentally determined by the length and mass of the vocal cords; within these limits, pitch may be varied by changing the combination of air pressure and tension of the vocal cords. This combination determines the frequency at which the vocal cords vibrate; the greater the frequency of vibration, the higher the pitch.

Another aspect of voice is resonance. After voice is produced, it is resonated in the chest, throat, and cavities of the mouth. The quality of the voice is determined by resonance and the manner in which the vocal cords vibrate; intensity is controlled by resonance and by the strength of the vibrations of the vocal cords.

III

Articulation

Articulation refers to the speech sounds that are produced to form the words of language. The articulating mechanism comprises the lips, tongue, teeth, jaw, and palate. Speech is articulated by interrupting or shaping both the vocalized and unvocalized airstream through movement of the tongue, lips, lower jaw, and soft palate. The teeth are used to produce some specific speech sounds.

---

---

IV

Language Skills and Other Factors

Language is an arbitrary system of abstract symbols agreed upon by any group of people to communicate their thoughts and feelings. Symbols may be verbal or nonverbal, that is, either spoken or written; additionally, nonverbal symbols may be gestures and body movements (See also Sign Language). In spoken language the skills of articulation are used; in written language, spelling is substituted for articulation. Both auditory and visual skills are essential to the comprehension and expression of language.

Rate and rhythm also should be considered in the evaluation of speech. Connected speech should not be so rapid or so slow that it interferes with comprehension. Rhythm is judged mostly in terms of fluency. Good or so-called normal speech cannot be exactly measured or described, however; it can be judged essentially only as it seems to be suitable to the sex, size, age, personality, and needs of the speaker.

	More from Encarta
	•  Presidential Myths Quiz •  Coffee break: Recharge your brain