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Voice, Speech, and Language Research
Why the NIDCD Supports Voice, Speech, and Language Research
Communication allows us to participate in society and is a defining characteristic of what it is to be human. Other organisms clearly communicate; however, in no other species does it appear that communication—specifically the use of language in communication—is as highly developed as in humans, nor as central to an organism’s function and identity. Communication impairments that involve voice, speech, or language often limit a person’s ability to participate in society, whether the activity is educational, occupational, or social. In addition, because effective communication is needed to get aid in life-threatening situations, loss of communication can put people at risk for compromised physical safety and survival.
Human communication requires the brain to integrate complex sensory signals collected by the peripheral organs and to produce neural signals to co-ordinate the muscles involved in speaking and signing language. Human communication systems also rely on the sensory functions of the peripheral organs responsible for hearing, balance, taste, and smell, located in the middle and inner ear, nose, mouth, and throat. They also involve vision (used for sign language and visible speech) and the development of abstract linguistic representations and memory mechanisms, located centrally in the brain. Additionally, communication systems rely on the motor functions of the hands and arms (for sign language and co-speech gesture) and on the peripheral organs of speech production, which include the diaphragm, airway, vocal folds, tongue, lips, and other oral structures.
The interplay between central and peripheral signals, genetics, and environment makes language acquisition a vulnerable process. We don’t understand the causes of many voice, speech, and language disorders, and the path to treatment is often uncertain. Our ability to develop effective treatment is hindered by gaps in evidence for age-appropriate clinical goals, targets of intervention, and expected change trajectories. Researchers are only beginning to understand the developmental course of voice, speech and language markers during childhood that serve as a guide for clinical interventions suited to particular levels of development. In addition, we also need more research on communication problems associated with diseases and disorders most commonly occurring in adults.
While spoken language is the primary way people communicate, it is not the only way. The symbolic nature of language allows us to attribute meaning through not only the voice, speech, language and hearing, but also using visual-manual modes of communication, most notably the use of sign languages and augmentative communication systems. The NIDCD supports research to understand these communication systems, their acquisition and development, and their use when spoken language systems are damaged by trauma or degenerative diseases, or when speech is difficult to acquire due to early hearing loss or injury to the nervous system. This research is also applicable to other human functions because enhanced understanding of visual-manual language systems opens a window into general human cognition.
Developmental Communication Disorders
Nearly 8 percent of children aged 3 to 17 years have had a communication disorder during the past 12 months, according to data from the National Health Interview Survey, 2012.193 In children, delayed speech and language acquisition or impairment are very often significant predictors of future academic, social, vocational, and adaptive outcomes.194-196 These impairments also tend to run in families197, with converging evidence of genetic effects.198 Many communication disorders, such as specific language impairment (SLI) and stuttering, first become apparent when a child normally begins to acquire speech and language. Other developmental disorders may also include communication problems, such as autism spectrum disorder (ASD), Fragile X, or cerebral palsy. One of the hallmarks of ASD is the diminished ability to communicate effectively—particularly in the expression and reception of language. The NIDCD is committed to supporting research efforts to improve the identification speech and language disorders in children and to improve treatments for those disorders.
Language and Literacy
Hearing loss in infancy and childhood may give rise to difficulties in acquiring spoken and written language skills. Children who are deaf are at greater risk for delays in learning to read. Children with normal hearing who have specific language impairment often have reading difficulties upon entry into school. Low proficiency in reading and writing limits job opportunities and economic success. Reading, writing, and communication skills are improving as we add more research on effective ways to teach and address literacy issues in these populations.
Voice and Voice Disorders
About 7.5 million people in the U.S. have trouble using their voice. Vocal fold tissue, a complex biological structure needed for normal voice production, is susceptible to damage from daily insults from environmental pollutants or acid reflux. Such damage may compromise vocal fold integrity over time.199, 200 Laryngeal disorders can cause a significant societal burden due to work-related disability, lost productivity, and direct health care cost (estimated at $11 billion annually).201, 202 The NIDCD supports basic, clinical, and translational research on laryngeal muscle structure and function with respect to normal and disordered voice use, including new prevention and treatment strategies.
Teachers are occupational voice users who represent one of the country’s largest group of employees. Teachers are particularly vulnerable to voice disorders. Between about 11 and 38 percent of teachers have a voice problem on any given day203-205, and cumulative estimates indicate nearly 60 percent of teachers have been affected over their working lives.203 Considering the impact of voice disorders for teachers—the diagnosis, treatment, and substitute teacher costs—the burden to the American economy is substantial, estimated to approach $3 billion annually in 1998.206
Communication Disorders and Neurodegenerative Disorders
Stroke is a leading cause of adult disability in the United States.207 A significant proportion of stroke survivors have communication disorders, such as post-stroke difficulty in using language (aphasia) or difficulty in articulating words (dysarthria) from brain injury. Additionally, neurodegenerative disorders, such as Parkinson’s disease or amyotrophic lateral sclerosis, and injury can lead to impairments in planning and executing motor speech production such as in apraxia or dysarthria. These types of communication problems are a strong predictor of increased isolation and poor quality of life.208 The NIDCD supports research to understand the neurological bases of voice, speech, and language impairments; the correlation of brain imaging data with prognosis; and the development of novel intervention strategies to improve outcomes.
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