ASSIGNMENT FOR 1BDS STUDENTS - BASED ON LECTURE 24 JAN 2013
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About Speech
Speech is a basic physiologic function involving lungs, pharynx, oral and nasal cavities. It is a mode of communication of humans. It is produced by a stream of acoustic vibrations created by the flow of air through the vocal tract.
Since generation of speech sounds mainly occur at oro-pharyngeal region tissue abnormalities in this area can affect speech. These structural and functional tissue abnormalities may be arising from a disorder or as a result of treatment procedures.
Main stages of human speech:
Phonation, Articulation, Resonance are subjected to neurological control.
Phonation is the production of basic vowel tone in larynx. Laryngeal function determines the process of phonation.
During articulation new sounds are created and modified with the help of articulators. These are categorised in to active and passive groups. Active articulators are lips, tongue, soft palate and pharynx. These structures move to obtain contacts with passive articulators such as teeth, alveolar ridge, hard palate and uvula.
Resonance, which occurs within the oral-pharyngeal-nasal cavities and paranasal sinuses, gives characteristic quality to the sound. Neurological control determines the arrangement of sounds to form a pattern of communication.
Video Fluoroscopy: Normal Velum movements during Speech
The velopharynx directs the passage of air column into nasopharynx during speech. Velopharyngeal port closure is achieved by normal apposition of the soft palate (velum) with the posterior and lateral pharyngeal walls2. Velopharyngeal dysfunction due to structural, neurogenic, physiological or mechanical causes results in improper closure.
Speech sounds are classified into vowels and consonants. Vowels ( a,e,i,o,u) are produced with minimum interruption to airflow. The shape of the mouth, pharynx and the tongue position determine each vowel. Parameters that describe vowels are the height of the tongue, backness of the tongue and whether lip rounding is taking place.
Consonants involve some obstruction to the airflow along the vocal tract. Parameters that describe consonants are whether vocal cord vibration is taking place, the place of the articulation (obstruction to the airflow) and the manner of articulation (degree of obstruction).
Altered structure and function of articulators and the oral environment bring about changes in articulation and resonance thereby affecting the speech outcome. Cleft lip & Palate abnormality is a congenital condition that affects speech due to the structural and functional changes in lips, alveolus, and hard palate affecting articulation of speech sounds. Furthermore velopharyngeal dysfunction due to soft palate defect brings about hypernasality, which is defined as perception of excessive amount of nasal resonance accompanying normal non-nasalized sounds. Various investigation modalities are being applied for the evaluation of hypernasal speech in children undergoing cleft surgery. These investigations are necessary to evaluate the success of treatment
Speech problems of patients with cleft palate
Children born with Cleft Lip and Palate abnormality have a normal larynx therefore PHONATION is normal
They may have abnormalities in palate and velum, pharynx, lips but a normal tongue
• Therefore ARTICULATION and RESONANCE is not normal
Speech Problems of patients with cleft palate
1. Hypernasality in voice
2. Weak consonants
3. Nasal emmission
4. Nasal grimace
5. Faulty articulation
6. Pharyngeal fricatives
7. Glottal stops
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