Dysarthria: Disorders of speech articulation caused by imperfect coordination of pharynx, larynx, tongue, or face muscles. This may result from CRANIAL NERVE DISEASES; NEUROMUSCULAR DISEASES; CEREBELLAR DISEASES; BASAL GANGLIA DISEASES; BRAIN STEM diseases; or diseases of the corticobulbar tracts (see PYRAMIDAL TRACTS). The cortical language centers are intact in this condition. (From Adams et al., Principles of Neurology, 6th ed, p489)Speech Intelligibility: Ability to make speech sounds that are recognizable.Speech Disorders: Acquired or developmental conditions marked by an impaired ability to comprehend or generate spoken forms of language.Speech Production Measurement: Measurement of parameters of the speech product such as vocal tone, loudness, pitch, voice quality, articulation, resonance, phonation, phonetic structure and prosody.Ataxia: Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or PERIPHERAL NERVE DISEASES. Motor ataxia may be associated with CEREBELLAR DISEASES; CEREBRAL CORTEX diseases; THALAMIC DISEASES; BASAL GANGLIA DISEASES; injury to the RED NUCLEUS; and other conditions.Articulation Disorders: Disorders of the quality of speech characterized by the substitution, omission, distortion, and addition of phonemes.Speech Articulation Tests: Tests of accuracy in pronouncing speech sounds, e.g., Iowa Pressure Articulation Test, Deep Test of Articulation, Templin-Darley Tests of Articulation, Goldman-Fristoe Test of Articulation, Screening Speech Articulation Test, Arizona Articulation Proficiency Scale.Mutism: The inability to generate oral-verbal expression, despite normal comprehension of speech. This may be associated with BRAIN DISEASES or MENTAL DISORDERS. Organic mutism may be associated with damage to the FRONTAL LOBE; BRAIN STEM; THALAMUS; and CEREBELLUM. Selective mutism is a psychological condition that usually affects children characterized by continuous refusal to speak in social situations by a child who is able and willing to speak to selected persons. Kussmal aphasia refers to mutism in psychosis. (From Fortschr Neurol Psychiatr 1994; 62(9):337-44)Speech Therapy: Treatment for individuals with speech defects and disorders that involves counseling and use of various exercises and aids to help the development of new speech habits.Speech Acoustics: The acoustic aspects of speech in terms of frequency, intensity, and time.Cerebellar Ataxia: Incoordination of voluntary movements that occur as a manifestation of CEREBELLAR DISEASES. Characteristic features include a tendency for limb movements to overshoot or undershoot a target (dysmetria), a tremor that occurs during attempted movements (intention TREMOR), impaired force and rhythm of diadochokinesis (rapidly alternating movements), and GAIT ATAXIA. (From Adams et al., Principles of Neurology, 6th ed, p90)Hypoglossal Nerve Diseases: Diseases of the twelfth cranial (hypoglossal) nerve or nuclei. The nuclei and fascicles of the nerve are located in the medulla, and the nerve exits the skull via the hypoglossal foramen and innervates the muscles of the tongue. Lower brain stem diseases, including ischemia and MOTOR NEURON DISEASES may affect the nuclei or nerve fascicles. The nerve may also be injured by diseases of the posterior fossa or skull base. Clinical manifestations include unilateral weakness of tongue musculature and lingual dysarthria, with deviation of the tongue towards the side of weakness upon attempted protrusion.Voice Quality: That component of SPEECH which gives the primary distinction to a given speaker's VOICE when pitch and loudness are excluded. It involves both phonatory and resonatory characteristics. Some of the descriptions of voice quality are harshness, breathiness and nasality.Metal Metabolism, Inborn ErrorsBrain Diseases, Metabolic, Inborn: Brain disorders resulting from inborn metabolic errors, primarily from enzymatic defects which lead to substrate accumulation, product reduction, or increase in toxic metabolites through alternate pathways. The majority of these conditions are familial, however spontaneous mutation may also occur in utero.Subthalamus: A transition zone in the anterior part of the diencephalon interposed between the thalamus, hypothalamus, and tegmentum of the mesencephalon. Components of the subthalamus include the SUBTHALAMIC NUCLEUS, zona incerta, nucleus of field H, and the nucleus of ansa lenticularis. The latter contains the ENTOPEDUNCULAR NUCLEUS.Communication Aids for Disabled: Equipment that provides mentally or physically disabled persons with a means of communication. The aids include display boards, typewriters, cathode ray tubes, computers, and speech synthesizers. The output of such aids includes written words, artificial speech, language signs, Morse code, and pictures.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Cranial Nerve Diseases: Disorders of one or more of the twelve cranial nerves. With the exception of the optic and olfactory nerves, this includes disorders of the brain stem nuclei from which the cranial nerves originate or terminate.Cerebral Infarction: The formation of an area of NECROSIS in the CEREBRUM caused by an insufficiency of arterial or venous blood flow. Infarcts of the cerebrum are generally classified by hemisphere (i.e., left vs. right), lobe (e.g., frontal lobe infarction), arterial distribution (e.g., INFARCTION, ANTERIOR CEREBRAL ARTERY), and etiology (e.g., embolic infarction).Speech: Communication through a system of conventional vocal symbols.Neurologic Examination: Assessment of sensory and motor responses and reflexes that is used to determine impairment of the nervous system.