Speech Disorders: Acquired or developmental conditions marked by an impaired ability to comprehend or generate spoken forms of language.Speech: Communication through a system of conventional vocal symbols.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.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 Perception: The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes).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 Intelligibility: Ability to make speech sounds that are recognizable.Apraxias: A group of cognitive disorders characterized by the inability to perform previously learned skills that cannot be attributed to deficits of motor or sensory function. The two major subtypes of this condition are ideomotor (see APRAXIA, IDEOMOTOR) and ideational apraxia, which refers to loss of the ability to mentally formulate the processes involved with performing an action. For example, dressing apraxia may result from an inability to mentally formulate the act of placing clothes on the body. Apraxias are generally associated with lesions of the dominant PARIETAL LOBE and supramarginal gyrus. (From Adams et al., Principles of Neurology, 6th ed, pp56-7)Stuttering: A disturbance in the normal fluency and time patterning of speech that is inappropriate for the individual's age. This disturbance is characterized by frequent repetitions or prolongations of sounds or syllables. Various other types of speech dysfluencies may also be involved including interjections, broken words, audible or silent blocking, circumlocutions, words produced with an excess of physical tension, and monosyllabic whole word repetitions. Stuttering may occur as a developmental condition in childhood or as an acquired disorder which may be associated with BRAIN INFARCTIONS and other BRAIN DISEASES. (From DSM-IV, 1994)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.Phonetics: The science or study of speech sounds and their production, transmission, and reception, and their analysis, classification, and transcription. (Random House Unabridged Dictionary, 2d ed)Enzyme Therapy: The use of enzymes to correct metabolic and physiological processes.Velopharyngeal Insufficiency: Failure of the SOFT PALATE to reach the posterior pharyngeal wall to close the opening between the oral and nasal cavities. Incomplete velopharyngeal closure is primarily related to surgeries (ADENOIDECTOMY; CLEFT PALATE) or an incompetent PALATOPHARYNGEAL SPHINCTER. It is characterized by hypernasal speech.Articulation Disorders: Disorders of the quality of speech characterized by the substitution, omission, distortion, and addition of phonemes.Speech Acoustics: The acoustic aspects of speech in terms of frequency, intensity, and time.Speech Discrimination Tests: Tests of the ability to hear and understand speech as determined by scoring the number of words in a word list repeated correctly.Language Development Disorders: Conditions characterized by language abilities (comprehension and expression of speech and writing) that are below the expected level for a given age, generally in the absence of an intellectual impairment. These conditions may be associated with DEAFNESS; BRAIN DISEASES; MENTAL DISORDERS; or environmental factors.Galactosemias: A group of inherited enzyme deficiencies which feature elevations of GALACTOSE in the blood. This condition may be associated with deficiencies of GALACTOKINASE; UDPGLUCOSE-HEXOSE-1-PHOSPHATE URIDYLYLTRANSFERASE; or UDPGLUCOSE 4-EPIMERASE. The classic form is caused by UDPglucose-Hexose-1-Phosphate Uridylyltransferase deficiency, and presents in infancy with FAILURE TO THRIVE; VOMITING; and INTRACRANIAL HYPERTENSION. Affected individuals also may develop MENTAL RETARDATION; JAUNDICE; hepatosplenomegaly; ovarian failure (PRIMARY OVARIAN INSUFFICIENCY); and cataracts. (From Menkes, Textbook of Child Neurology, 5th ed, pp61-3)Voice Disorders: Pathological processes that affect voice production, usually involving VOCAL CORDS and the LARYNGEAL MUCOSA. Voice disorders can be caused by organic (anatomical), or functional (emotional or psychological) factors leading to DYSPHONIA; APHONIA; and defects in VOICE QUALITY, loudness, and pitch.Audiometry, Speech: Measurement of the ability to hear speech under various conditions of intensity and noise interference using sound-field as well as earphones and bone oscillators.Speech Recognition Software: Software capable of recognizing dictation and transcribing the spoken words into written text.Speech Reception Threshold Test: A test to determine the lowest sound intensity level at which fifty percent or more of the spondaic test words (words of two syllables having equal stress) are repeated correctly.Bipolar Disorder: A major affective disorder marked by severe mood swings (manic or major depressive episodes) and a tendency to remission and recurrence.Sound Spectrography: The graphic registration of the frequency and intensity of sounds, such as speech, infant crying, and animal vocalizations.Acoustic Stimulation: Use of sound to elicit a response in the nervous system.Cochlear Implants: Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.Noise: Any sound which is unwanted or interferes with HEARING other sounds.Mental Disorders: Psychiatric illness or diseases manifested by breakdowns in the adaptational process expressed primarily as abnormalities of thought, feeling, and behavior producing either distress or impairment of function.Speech, Esophageal: A method of speech used after laryngectomy, with sound produced by vibration of the column of air in the esophagus against the contracting cricopharyngeal sphincter. (Dorland, 27th ed)Anxiety Disorders: Persistent and disabling ANXIETY.Mood Disorders: Those disorders that have a disturbance in mood as their predominant feature.Voice: The sounds produced by humans by the passage of air through the LARYNX and over the VOCAL CORDS, and then modified by the resonance organs, the NASOPHARYNX, and the MOUTH.Speech, Alaryngeal: Methods of enabling a patient without a larynx or with a non-functional larynx to produce voice or speech. The methods may be pneumatic or electronic.Language: A verbal or nonverbal means of communicating ideas or feelings.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.Perceptual Masking: The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.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.Auditory Perception: The process whereby auditory stimuli are selected, organized, and interpreted by the organism.Cochlear Implantation: Surgical insertion of an electronic hearing device (COCHLEAR IMPLANTS) with electrodes to the COCHLEAR NERVE in the inner ear to create sound sensation in patients with residual nerve fibers.Linguistics: The science of language, including phonetics, phonology, morphology, syntax, semantics, pragmatics, and historical linguistics. (Random House Unabridged Dictionary, 2d ed)Diagnostic and Statistical Manual of Mental Disorders: Categorical classification of MENTAL DISORDERS based on criteria sets with defining features. It is produced by the American Psychiatric Association. (DSM-IV, page xxii)Auditory Threshold: The audibility limit of discriminating sound intensity and pitch.Lipreading: The process by which an observer comprehends speech by watching the movements of the speaker's lips without hearing the speaker's voice.