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Speech-language pathology and audiology are the two clinical professions, and the associated research fields, that deal with human communication and its disorders. Together with the basic sciences behind them, they make up the discipline usually called communication sciences and disorders (CSD). Speech-language pathologists (SLPs) work with speech, language, voice, fluency, cognition-communication and swallowing; audiologists work with hearing and balance. This guide explains what the field covers, how its subfields and methods are organized, how people are trained, who funds and publishes the research, and what is distinctive about running research studies with participants who have communication disorders. It is an educational overview of a research discipline, not clinical advice.
What Is Speech-Language Pathology?
Speech-language pathology is the health profession concerned with the assessment, treatment and prevention of disorders of speech, language, voice, fluency, social communication and swallowing. In the United Kingdom, Ireland and several other countries the same profession is called speech and language therapy, and its practitioners are speech and language therapists. In everyday conversation the work is often called speech therapy, which is a narrower label than the field itself: much of what SLPs do concerns language comprehension and expression, cognition and communication, and feeding and swallowing rather than the articulation of speech sounds alone. When searching the research literature, it pays to try all of these terms, because a search using only one will miss part of the evidence.
As a research field, speech-language pathology asks questions such as: how typical speech and language develop in children and how they change with age; what distinguishes a developmental language disorder from normal variation; how stroke, brain injury and neurodegenerative disease alter language and speech; which interventions improve communication or safe swallowing, for whom, and at what dose; and how to measure communication in a way that matters to the person and their family and not only to a test score.
What Is Audiology?
Audiology is the health profession and science of hearing, balance and their disorders. Audiologists evaluate hearing and balance function, fit and manage hearing aids and other hearing technology, work with cochlear implant programs, and counsel patients and families. Audiology research spans basic auditory science (how the ear and auditory brain process sound), the epidemiology of hearing loss, diagnostic test development, hearing technology outcomes, and the study of tinnitus and balance disorders. This page is the discipline-level explainer; the audiology clinic supply checklist is a separate, operational resource.
Communication Sciences and Disorders: The Umbrella Field
CSD is the academic home for both professions plus the speech, language and hearing sciences. It draws on linguistics, psychology, neuroscience, acoustics, physiology, education and engineering. A typical CSD department teaches future clinicians and also houses laboratories studying acoustics of speech, brain imaging of language, auditory physiology or the epidemiology of communication problems. The clinical and basic research traditions are deliberately close: a clinician’s question (why does this treatment help some children with a language disorder and not others?) is often a basic science question in disguise.
How the Field Relates to Neighboring Disciplines
- Linguistics supplies the descriptive framework for sounds, words, grammar and meaning. Clinical linguistics applies it to disordered speech and language. Sociolinguistics adds the reminder that dialect and multilingualism are differences, not disorders, which is central to fair assessment of children and adults who speak more than one language or dialect.
- Neurology and neuroscience explain the brain conditions, such as stroke, traumatic brain injury and Parkinson disease, that commonly cause aphasia, dysarthria, apraxia of speech and dysphagia (swallowing disorders). SLPs often work alongside neurologists in rehabilitation teams.
- Physical therapy and rehabilitation science share trial design problems with SLP research: complex, multi-component interventions, difficulty blinding, and heterogeneous patients.
- Communication studies is a different field: it examines human communication in social, media and organizational settings, not communication disorders or hearing.
- Cognitive science and geriatrics overlap with the study of language processing, memory and communication changes in aging.
Major Subfields
Speech and Language Development and Disorders
This area covers speech sound disorders, developmental language disorder, stuttering and fluency, late talking, and communication in autism and other developmental conditions. Research here uses longitudinal cohorts, language sampling, standardized assessments and randomized trials of intervention. Shared corpora of child language, such as the one described in the TalkBank and CHILDES repository guide, are a major data-sharing infrastructure for the field.
Acquired Neurogenic Communication Disorders
Aphasia, motor speech disorders, and cognitive-communication disorders after stroke, brain injury or neurodegenerative disease form a large research area. Studies combine behavioral measures with neuroimaging and increasingly with telepractice delivery models.
Voice and Resonance
Voice science examines the production of voice, voice disorders, and the effects of surgery, aging and occupational voice use. It relies on acoustic and aerodynamic measurement and on endoscopic imaging.
Swallowing (Dysphagia)
Swallowing disorders can result from stroke, neurodegenerative disease, head and neck cancer treatment and aging. Research examines instrumental assessment, safety and aspiration risk, and rehabilitation exercises. Swallowing is a good example of why the field is broader than the term “speech therapy” suggests.
Hearing Science and Audiology
Hearing research covers auditory physiology, the epidemiology and consequences of hearing loss, hearing aids and cochlear implants, auditory processing, tinnitus, and vestibular (balance) function.
Augmentative and Alternative Communication and Technology
Augmentative and alternative communication (AAC) research studies tools and strategies, from picture boards to speech-generating devices, that support people who cannot rely on natural speech. Speech technology and signal processing research increasingly overlaps with this work.
Research Methods in Communication Sciences and Disorders
The field uses the full toolkit of behavioral and health research, and several designs are especially characteristic.
- Single-case experimental designs. Because communication disorders are heterogeneous and populations can be small, multiple-baseline and other single-case designs are widely used to show that a change follows an intervention in a given participant.
- Randomized and pragmatic trials. Group trials of treatment are common, with the usual challenges of rehabilitation research: the therapist cannot be blinded, treatment is complex and delivered by humans, and dosage must be reported carefully. See the research methods hub for background on trial design.
- Acoustic, physiological and instrumental measurement. Speech acoustics, aerodynamic measures, imaging of the swallow, and audiometry produce quantitative outcomes with their own reliability concerns.
- Language sampling and discourse analysis. Recording and transcribing speech, then coding it, is central; see transcription conventions in qualitative research and how to conduct a discourse analysis.
- Standardized and patient-reported measures. Choosing an outcome measure that is valid for the population is a core design decision; see choosing and validating a patient-reported outcome measure and minimal detectable change.
- Neuroimaging and electrophysiology. EEG, MRI and related methods are used to study language and auditory processing.
- Epidemiology and population surveys. Prevalence and risk-factor studies of hearing loss and communication disorders inform public health planning.
Research Ethics: Consent, Capacity and Communication Access
Research on communication disorders raises a specific ethics problem: the usual route to informed consent is itself a communication task. A participant with aphasia, a child with a language disorder, an adult with dementia, or a person who is deaf or hard of hearing may be fully able to decide yet unable to understand a standard consent form delivered in dense written or spoken language. Treating limited communication as limited decision-making capacity is an error in both directions: it can exclude capable people from research, or lead to consent that is not truly informed.
General principles that apply are summarized in these existing CASRAI resources:
- The Belmont Report principles of respect for persons, beneficence and justice underlie the whole framework.
- Vulnerable populations in research and the U.S. federal rules for children in research (45 CFR 46 Subpart D) matter for pediatric speech and language studies. The concept of assent is central when a child is old enough to take part in the decision.
- The Mental Capacity Act 2005 consultee model is one example of how a legal system handles participants who may lack capacity.
- The role of the institutional review board is to review whether consent processes are appropriate for the intended participants.
Common good practice in this field includes communication-accessible consent materials (plain language, large print, pictures, short sentences, extra time), supported conversation techniques, interpreters or sign-language support for deaf participants, assessing capacity for the specific decision rather than assuming it, and involving family or communication partners only in ways the participant would endorse. Protocol and IRB submissions should state how consent will be made accessible, not just that it will be obtained. Researchers should follow the requirements of their own institution and jurisdiction.
Training and Career Pathways
Clinical entry to speech-language pathology is at the graduate level in the United States, followed by a supervised, mentored professional experience and a national examination. Audiologists also train at the graduate level in clinical programs. ASHA offers the Certificate of Clinical Competence in Speech-Language Pathology (CCC-SLP) and the Certificate of Clinical Competence in Audiology (CCC-A), and also certifies audiology and speech-language pathology assistants. State licensure is separate and required for clinical practice in the United States; other countries have their own regulators and routes. Requirements change, so confirm current ones with the relevant body before relying on them.
Research careers typically run through a doctoral degree (PhD, or a clinical doctorate plus research training) in CSD or a related field such as linguistics, psychology or neuroscience, followed by postdoctoral training. Many faculty are clinician-scientists who maintain a clinical credential while directing a laboratory.
Professional Societies
The American Speech-Language-Hearing Association (ASHA) is the national professional, scientific and credentialing association for audiologists, speech-language pathologists, and speech, language and hearing scientists in the United States. ASHA describes itself as representing 247,000 members, certificate holders and affiliates, and marked its 100th anniversary in 2025. Other bodies include the American Academy of Audiology, the Royal College of Speech and Language Therapists in the United Kingdom, and Speech Pathology Australia, along with many national and specialty societies for voice, fluency, aphasia, AAC and hearing science. Check each body’s own site for current membership figures and standards.
Who Funds Communication Sciences and Disorders Research?
In the United States the principal public funder is the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health. NIDCD was established in 1988 and supports research on hearing, balance, taste, smell, voice, speech and language. Other NIH institutes also fund relevant work, for instance on child development, neurological disease, aging and rehabilitation, and other federal agencies, private foundations and disease-focused organizations add further funding, while industry funds hearing-technology work. In other countries, national research councils and health agencies play the equivalent role.
For practical help with applications, see NIH specific aims page examples and NIH paylines. Always check the current funding announcements and the institute’s own pages for priorities, as these change with each strategic plan.
Journals and Publishing
ASHA publishes several peer-reviewed journals, including the Journal of Speech, Language, and Hearing Research, the American Journal of Audiology, the American Journal of Speech-Language Pathology and Language, Speech, and Hearing Services in Schools. The field also publishes in many journals in linguistics, neurology, otolaryngology, psychology and acoustics. Reporting guidelines for trials and single-case studies, and open data practices for shared speech corpora, apply as in other health fields.
The Research Administration Link
For research administrators, communication disorders research has a few recurring features. Studies often involve children or adults with cognitive-communication impairments, so IRB review and consent accessibility need early attention. Audio and video recordings of speech are identifiable data, and recorded voices can be difficult to de-identify, which affects data management plans and sharing decisions. Clinical sites such as school systems, hospital rehabilitation units and community clinics need agreements and a clear division of responsibilities. Many projects are small, single-lab efforts funded through NIH R-series mechanisms and local grants, while large cohorts and clinical trials need multisite coordination. Equipment such as sound-treated booths, audiometers and instrumental swallow assessment tools is specialized and shapes budgets and space planning.
Frequently Asked Questions
What is the difference between speech-language pathology and audiology?
Speech-language pathology concerns speech, language, voice, fluency, cognition-communication and swallowing. Audiology concerns hearing and balance. They are separate professions with separate training and credentials, grouped together in CSD because hearing and communication are closely linked.
Is speech therapy the same as speech-language pathology?
Speech therapy is the common name for part of what SLPs do. The profession is broader and includes language, cognition, voice and swallowing. In the UK, the profession is named speech and language therapy.
What are communication disorders?
Communication disorders are conditions that affect the ability to receive, send, process or understand verbal, nonverbal or graphic communication. They include speech, language, hearing and voice disorders. They can be developmental or acquired.
What does NIDCD fund?
NIDCD funds research on hearing, balance, taste, smell, voice, speech and language. See the funders section above.
Does limited speech mean a person cannot consent to research?
No. Communication ability and decision-making capacity are different things. Researchers should provide accessible consent processes and assess capacity for the specific decision. See the research ethics section above.
Where can I find child language data for research?
Shared repositories such as TalkBank and CHILDES are widely used; see our guide to that repository.
