Phonetics is a branch of linguistics that studies how humans produce and perceive sounds, or in the case of sign languages, the equivalent aspects of sign. Phoneticians—linguists who specialize in phonetics—study the physical properties of speech. The field of phonetics is traditionally divided into three sub-disciplines based on the research questions involved such as how humans plan and execute movements to produce speech, how various movements affect the properties of the resulting sound, or how humans convert sound waves to linguistic information. Traditionally, the minimal linguistic unit of phonetics is the phone—a speech sound in a language—which differs from the phonological unit of phoneme; the phoneme is an abstract categorization of phones.
The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, and use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition.
This is a glossary of medical terms related to communications disorders which are conditions that could have the potential to negatively impact the level at which an individual can hear, understand, and respond to others.
Speech disorders or speech impairments are a type of communication disorder where normal speech is disrupted. This can mean stuttering, lisps, etc. Someone who is unable to speak due to a speech disorder is considered mute. Speech disorders affect roughly 11.5% of the US population. Speech is a complex process that requires precise timing, nerve and muscle control. The ability to understand language and produce speech is coordinated by the brain. A person who suffers from a stroke, an accident or birth defect may have speech and language problems.
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phoneme. In other words, it is a condition in which problems effectively occur with the muscles that help produce speech, often making it very difficult to pronounce words. It is unrelated to problems with understanding language, although a person can have both. Any of the speech subsystems can be affected, leading to impairments in intelligibility, audibility, naturalness, and efficiency of vocal communication. Dysarthria that has progressed to a total loss of speech is referred to as anarthria. The term dysarthria is from New Latin, dys- "dysfunctional, impaired" and arthr- "joint, vocal articulation".
A hoarse voice, also known as dysphonia or hoarseness, is when the voice involuntarily sounds breathy, raspy, or strained, or is softer in volume or lower in pitch. A hoarse voice, can be associated with a feeling of unease or scratchiness in the throat. Hoarseness is often a symptom of problems in the vocal folds of the larynx. It may be caused by laryngitis, which in turn may be caused by an upper respiratory infection, a cold, or allergies. Cheering at sporting events, speaking loudly in noisy situations, talking for too long without resting one's voice, singing loudly, or speaking with a voice that's too high or too low can also cause temporary hoarseness. A number of other causes for losing one's voice exist, and treatment is generally by resting the voice and treating the underlying cause. If the cause is misuse or overuse of the voice, drinking plenty of water may alleviate the problems.
A nerve root is the initial segment of a nerve leaving the central nervous system. Nerve roots can be classified as:
Fazio–Londe disease (FLD), also called progressive bulbar palsy of childhood, is a very rare inherited motor neuron disease of children and young adults and is characterized by progressive paralysis of muscles innervated by cranial nerves.
Pharyngeal flap surgery is a procedure to correct the airflow during speech. The procedure is common among people with cleft palate and some types of dysarthria.
Velopharyngeal insufficiency is a disorder of structure that causes a failure of the velum to close against the posterior pharyngeal wall during speech in order to close off the nose during oral speech production. This is important because speech requires sound and airflow to be directed into the oral cavity (mouth) for the production of all speech sound with the exception of nasal sounds. If complete closure does not occur during speech, this can cause hypernasality and/or audible nasal emission during speech. In addition, there may be inadequate airflow to produce most consonants, making them sound weak or omitted.
Vocal cord paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerves (RLNs), which control all muscles of the larynx except for the cricothyroid muscle. The RLN is important for speaking, breathing and swallowing.
A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the lower motor neuron(s) in the anterior horn/anterior grey column of the spinal cord, or in the motor nuclei of the cranial nerves, to the relevant muscle(s).
Apraxia of speech is a speech sound disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia, AOS affects volitional movement patterns, however AOS usually also affects automatic speech.
Myelomalacia is a pathological term referring to the softening of the spinal cord. Possible causes of myelomalacia include cervical myelopathy, hemorrhagic infarction, or acute injury, such as that caused by intervertebral disc extrusion.
Voice therapy consists of techniques and procedures that target vocal parameters, such as vocal fold closure, pitch, volume, and quality. This therapy is provided by speech-language pathologists and is primarily used to aid in the management of voice disorders, or for altering the overall quality of voice, as in the case of transgender voice therapy. Vocal pedagogy is a related field to alter voice for the purpose of singing. Voice therapy may also serve to teach preventive measures such as vocal hygiene and other safe speaking or singing practices.
Speech and language impairment are basic categories that might be drawn in issues of communication involve hearing, speech, language, and fluency.
Motor speech disorders are a class of speech disorders that disturb the body's natural ability to speak due to neurologic impairments. These neurologic impairments make it difficult for individuals with motor speech disorders to plan, program, control, coordinate, and execute speech productions. Disturbances to the individual's natural ability to speak vary in their etiology based on the integrity and integration of cognitive, neuromuscular, and musculoskeletal activities. Speaking is an act dependent on thought and timed execution of airflow and oral motor / oral placement of the lips, tongue, and jaw that can be disrupted by weakness in oral musculature (dysarthria) or an inability to execute the motor movements needed for specific speech sound production. Such deficits can be related to pathology of the nervous system that affect the timing of respiration, phonation, prosody, and articulation in isolation or in conjunction.
Hypernasal speech is a disorder that causes abnormal resonance in a human's voice due to increased airflow through the nose during speech. It is caused by an open nasal cavity resulting from an incomplete closure of the soft palate and/or velopharyngeal sphincter. In normal speech, nasality is referred to as nasalization and is a linguistic category that can apply to vowels or consonants in a specific language. The primary underlying physical variable determining the degree of nasality in normal speech is the opening and closing of a velopharyngeal passageway between the oral vocal tract and the nasal vocal tract. In the normal vocal tract anatomy, this opening is controlled by lowering and raising the velum or soft palate, to open or close, respectively, the velopharyngeal passageway.
Alternating hemiplegia is a form of hemiplegia that has an ipsilateral cranial nerve palsies and contralateral hemiplegia or hemiparesis of extremities of the body. The disorder is characterized by recurrent episodes of paralysis on one side of the body. There are multiple forms of alternating hemiplegia, Weber's syndrome, middle alternating hemiplegia, and inferior alternating hemiplegia. This type of syndrome can result from a unilateral lesion in the brainstem affecting both upper motor neurons and lower motor neurons. The muscles that would receive signals from these damaged upper motor neurons result in spastic paralysis. With a lesion in the brainstem, this affects the majority of limb and trunk muscles on the contralateral side due to the upper motor neurons decussation after the brainstem. The cranial nerves and cranial nerve nuclei are also located in the brainstem making them susceptible to damage from a brainstem lesion. Cranial nerves III (Oculomotor), VI (Abducens), and XII (Hypoglossal) are most often associated with this syndrome given their close proximity with the pyramidal tract, the location which upper motor neurons are in on their way to the spinal cord. Damages to these structures produce the ipsilateral presentation of paralysis or palsy due to the lack of cranial nerve decussation before innervating their target muscles. The paralysis may be brief or it may last for several days, many times the episodes will resolve after sleep. Some common symptoms of alternating hemiplegia are mental impairment, gait and balance difficulties, excessive sweating and changes in body temperature.
Congenital bilateral perisylvian syndrome (CBPS) is a rare neurological disease characterized by paralysis of certain facial muscles and epileptic seizures.
