Incidence of voice disorders refers to the number of new cases identified in a specific time period.

Prevalence refers to the number of individuals who are living with voice disorders in a given time period.

Estimates of incidence and prevalence vary due to a number of factors, including etiology, age, gender, and occupation.

Age

In the pediatric population, the reported prevalence of a voice disorder has ranged from 1.4% to 6.0% (Black et al., 2015; Carding et al., 2006). Longer stays in the neonatal intensive care unit and prolonged intubation (more than 28 days) were associated with more severe dysphonia in premature infants (Hseu et al., 2018). An estimated range of 41%–73% of children were identified with vocal nodules, indicating vocal nodules as a predominant cause of pediatric dysphonia (Martins et al., 2015); however, there can be a variety of causes other than vocal fold nodules that result in dysphonia in the pediatric population. Rates indicated no statistically significant differences across race in preschool-aged children (Duff et al., 2004).

Approximately one out of 13 adults in the United States will experience a voice problem annually, but only a relative minority seek treatment (10%; Bhattacharyya, 2014). The rate of young adults (aged 24–34 years) with voice disorders was estimated to be 6%, with no significant difference across age groups, race/ethnicity, or education levels (Bainbridge et al., 2017). Prevalence was reported to be higher in adults aged 60 years and older, with estimates ranging from 4.8% to 29.1% in population-based studies (de Araújo Pernambuco et al., 2014).

Among adults (between 19 and 60 years of age) with a voice disorder, the most frequent diagnoses included functional dysphonia (20.5%), acid laryngitis (12.5%), and vocal polyps (12%; Martins et al., 2015).

Of individuals over the age of 60 years who had been evaluated for vocal problems, voice disorders were most commonly associated with presbyphonia (changes associated with aging voice), reflux/inflammation, functional dysphonia, vocal fold paralysis/paresis, and Reinke’s edema (Martins et al., 2015). Laryngeal cancer diagnoses were reported to have peaked in adults between 75 and 79 years of age and decreased thereafter (Roy et al., 2016).

Gender

Studies reported results based on gender; however, there were no indications whether the data collected were based on sex assigned at birth and/or gender identity. Voice disorders were reported to be significantly more prevalent in male children than in female children (Carding et al., 2006; Martins et al., 2015). In adulthood, however, prevalence was higher in female adults than in male adults, with a reported ratio of 1.5:1.0 (Martins et al., 2015; Roy et al., 2005).

Although female adults more frequently received diagnoses of dysphonia with no specific cause noted, male adults were more frequently diagnosed with chronic laryngitis (Cohen et al., 2012). Also, after the age of 40 years, male adults had higher prevalence rates of laryngeal cancer than female adults (Cohen et al., 2012).

Occupation

Teachers were estimated to be two to three times more likely than the general population to develop a voice disorder (Martins et al., 2014). Certain factors, such as number of classes per week, noise generated outside of the school setting, and volume of voice while lecturing, were indicated to increase the risk of teachers developing a voice disorder (Byeon, 2019).

The mean prevalence of voice disorders was estimated to be 46% among singers (Pestana et al., 2017). The most prevalent laryngeal pathologies and voice disorder symptoms reported in singers included, but were not limited to, Reinke’s edema, polyps, gastroesophageal reflux disease, laryngeal pain, and hoarseness; however, risk of developing laryngeal pathologies or vocal cord symptoms may vary based on differences in singing style and genre (Kwok & Eslick, 2019).

According to a claims-based study, almost 30% of dysphonia claims were individuals in the service industry. Those in the service industry were estimated to be 2.6 times more likely to develop benign laryngeal growth and individuals in the manufacturing industry were estimated to be 1.4 times more likely to develop malignant laryngeal growth compared to the general population (Benninger et al., 2017).

The term dysphonia encompasses the auditory-perceptual symptoms of voice disorders. Dysphonia is characterized by altered vocal quality, pitch, loudness, or vocal effort.

Perceptual signs and symptoms of dysphonia include

• rough vocal quality (raspy, audible aperiodicity in sound);
• breathy vocal quality (audible air escape in the sound signal or bursts of breathiness);
• strained vocal quality (increased effort; tense or harsh);
• strangled vocal quality (as if talking with breath held);
• abnormal pitch (too high, too low, pitch breaks, decreased pitch range);
• abnormal loudness/volume (too high, too low, decreased range, unsteady volume);
• abnormal resonance (hypernasal, hyponasal, cul-de-sac resonance);
• aphonia (loss of voice);
• phonation breaks;
• asthenia (weak voice);
• gurgly/wet-sounding voice;
• pulsed voice (fry register, audible creaks or pulses in sound);
• shrill voice (high, piercing sound, as if stifling a scream); and
• tremorous voice (shaky voice; rhythmic pitch and loudness undulations).

Other signs and symptoms include

• increased vocal effort associated with speaking,
• decreased vocal endurance or onset of fatigue with prolonged voice use,
• variable vocal quality throughout the day or during speaking,
• running out of breath quickly,
• frequent coughing or throat clearing (may worsen with increased voice use), and
• excessive throat or laryngeal tension/pain/tenderness.

Signs and symptoms can occur in isolation or in combination. As treatment progresses, some may dissipate, and others may emerge as compensatory strategies are eliminated.

Auditory-perceptual quality of voice in individuals with voice disorders can vary depending on the type and severity of the disorder, the size and site of the lesion (if present), and the individual’s compensatory responses. The severity of the voice disorder cannot always be determined by auditory-perceptual voice quality alone. Therefore, further instrumental assessment may be indicated to determine the severity and/or etiology of a voice disorder.

Normal voice production depends on power and airflow supplied by

• the respiratory system;
• laryngeal muscle activation;
• balance, coordination, and stamina of respiration, phonation, and resonation subsystems; and
• coordination among the above and the following supraglottic resonatory structures:
  • pharynx,
  • oral cavity, and
  • nasal cavity.

A disturbance in one of these subsystems or in the physiological balance among the systems may lead to or contribute to a voice disorder. Disruptions can be due to organic, functional, and/or psychogenic causes.

Organic causes include the following:

• structural
  • vocal fold abnormalities such as
    • vocal nodules, cysts, or polyps
    • edema
    • glottal stenosis
    • recurrent respiratory papilloma
    • sarcopenia (muscle atrophy associated with aging)
  • inflammation of the larynx due to issues such as
    • arthritis of the cricoarytenoid or cricothyroid,
    • laryngitis, or
    • laryngopharyngeal reflux
  • trauma to the larynx such as
    • intubation trauma
    • chemical exposure
    • external trauma
• neurologic
  • recurrent laryngeal nerve paralysis
  • adductor/abductor spasmodic dysphonia
  • Parkinson’s disease
  • multiple sclerosis
  • pseudobulbar palsy

Functional causes include the following:

• phonotrauma such as
• yelling
• screaming
• excessive throat clearing/coughing
• speaking in too high or too low pitch
• muscle tension dysphonia
• ventricular phonation
• vocal fatigue due to
• effort
• overuse

Psychogenic causes include the following:

• chronic stress disorders
• anxiety
• depression
• conversion reaction such as
• conversion aphonia
• conversion dysphonia

Making modifications to pitch without the guidance of a skilled service provider is not recommended and may result in vocal misuse. However, voice services may be provided to assist with appropriate pitch modifications.

Recognizing associations among these factors, along with patient history, may help in identifying the possible causes of the voice disorder. Even when an obvious cause is identified and treated, the voice problem may persist. For example, an upper respiratory infection could be the cause of the dysphonia, but poor or inefficient compensatory techniques may cause dysphonia to persist, even when the infection has been successfully treated.

SLPs play a central role in the assessment, diagnosis, and treatment of voice disorders. The professional roles and activities in speech-language pathology include the following:

• clinical services
  • diagnosis
  • assessment
  • planning
  • treatment
• prevention and advocacy
• education
• administration
• research

SLPs are trained to evaluate voice use and function to determine the cause of reported symptoms and select treatment methods for improving voice production.

Appropriate roles for SLPs include the following:

• Provide prevention information to individuals and groups known to be at risk for voice disorders, as well as to individuals working with those at risk.
• Conduct a comprehensive voice assessment, including clinical and instrumental evaluation.
• Identify normal and abnormal vocal function, describe perceptual qualities of voice, and assess vocal habits.
• Diagnose a voice disorder.
• Refer individuals to other professionals as needed to obtain a medical diagnosis (e.g., unilateral vocal fold immobility as the cause of dysphonia).
• Refer individuals to other health care professionals when medical/surgical or psychological evaluation and treatment are indicated and facilitate patient access to comprehensive services.
• Make decisions about management of voice disorders and develop culturally responsive treatment plans.
• Provide treatment, document progress, and determine appropriate dismissal criteria.
• Counsel patients and provide education aimed at preventing further complications from voice disorders.
• Serve as an integral member of a collaborative team (see ASHA’s resources on collaboration and teaming and interprofessional education/interprofessional practice [IPE/IPP]) that includes professionals such as
• otolaryngologists/laryngologists,
• pulmonologists,
• allergists,
• gastroenterologists,
• neurologists,
• endocrinologists,
• mental health professionals, and
• vocal coaches or voice teachers.
• Consult with other professionals, family members, and caregivers to facilitate program development and to provide
• supervision,
• evaluation, and/or
• expert testimony (as appropriate).
• Remain informed of research related to voice disorders and help advance the knowledge base related to the nature and treatment of voice disorders.
• Advocate for individuals with voice disorders at the local, state, and national levels.

As indicated in the ASHA Code of Ethics (ASHA, 2016a), SLPs who serve this population should be specifically educated and appropriately trained to do so.

Screening

Screening may be conducted if a voice disorder is suspected. It may be triggered by concerns from individuals, parents, teachers, or health care providers. When deviations from normal voice are detected during screening, further evaluation is warranted.

Screening includes evaluation of vocal characteristics related to

• respiration;
• phonation;
• resonance; and
• vocal range and flexibility, such as
  • pitch,
  • loudness,
  • pitch range, and
  • endurance.

Clinicians may use a formal screening tool (Lee et al., 2004) or obtain data using informal tasks. Standardized self-report questionnaires can be included for a more thorough screening (e.g., Deary et al., 2003; Hogikyan & Sethuraman, 1999; Jacobson et al., 1997).

Comprehensive Assessment

All patients/clients with voice disorders should be examined by a physician, preferably in a discipline appropriate to the presenting complaint. The physician’s examination may occur before or after the voice evaluation by the SLP. Consultation with an otolaryngologist can be important, particularly in the case that an SLP does not have access to instrumentation for evaluation. Assessment and treatment of voice disorders may require use of appropriate personal protective equipment.

A comprehensive assessment is conducted for individuals suspected of having a voice disorder, using both standardized and nonstandardized measures (see ASHA’s resource on assessment tools, techniques, and data sources). For a review of clinical voice assessments, see Roy et al. (2013).

Diagnostic therapy may be performed as part of the comprehensive assessment to help in making a diagnosis and to determine if the individual is stimulable to voice therapy efforts.

Comprehensive assessment is conducted to identify and describe

• impairments in body structure and function, including underlying strengths and weaknesses in speech sound production and verbal/nonverbal communication;
• comorbid deficits such as other health conditions and medications that can affect voice;
• limitations in activity and participation, including functional status in communication and interpersonal interactions;
• contextual (environmental and personal) factors that affect communication and life participation; and
• quality of life related to communication impairment and functional limitations.

See ASHA’s resource titled person-centered focus on function: voice [PDF] for an example of assessment data.

Comprehensive Assessment for Voice Disorders: Typical Components

Case History

• the individual’s description of the voice problem, including onset and variability of symptoms
• medical status and history, including surgeries, chronic disorders, and medications
• previous voice treatment
• daily habits related to vocal hygiene

Self-Assessment

• the individual’s self-perception of voice/vocal quality
• the individual’s assessment of how the voice problem affects
  • emotions and self-image and
  • the ability to communicate effectively in everyday activities as well as in social and work settings (e.g., Hogikyan & Sethuraman, 1999; Jacobson et al., 1997; Ma & Yiu, 2001)

Oral-Peripheral Examination

• assessment of structural or motor-based deficits that may affect communication and voice, including oral musculature, strength, speed, and range of motion
• assessment (during rest and purposeful speech tasks) of symmetry and movement of structures of the face, oral cavity, head, neck, and respiratory system
• testing of mechano-sensation of face and oral cavity
• testing of chemo-sensation (i.e., taste and smell)
• assessment of laryngeal sensations (dryness, tickling, burning, pain, etc.) and palpation of extrinsic laryngeal musculature, as indicated

Assessment of Respiration

• respiratory pattern (abdominal, thoracic, clavicular)
• coordination of respiration with phonation (breath-holding patterns, habitual use of residual air, length of breath groups)
• maximum phonation time (Dejonckere, 2010; Speyer et al., 2010)
• s/z ratio to assess for glottal insufficiency, which may be indicative of laryngeal pathology (Eckel & Boone, 1981; Stemple et al., 2010)

Auditory-Perceptual Assessment

This subjective assessment is based on the clinical impressions of the SLP during production of sustained vowels, sentences, and running speech.

Voice Quality

• roughness—irregularity in voicing source
• breathiness—audible air escape in voice
• strain—perception of excessive vocal effort
• pitch—perceptual correlate of fundamental frequency
• loudness—perceptual correlate of sound intensity
• overall severity—global, integrated impression of voice deviance
• additional perceptual features
• diplophonia
• aphonia
• pitch instability
• tremor
• vocal fry
• falsetto
• wet/gurgly quality

The perceptual features above are defined in ASHA’s Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V; ASHA, n.d., 2002; Kempster et al., 2009).

Resonance

See ASHA’s Practice Portal page on Resonance Disorders.

• Assess resonance quality, such as
• normal,
• hyponasal,
• hypernasal, or
• cul-de-sac.
• If abnormal, assess stimulability for normal resonance.
• If normal, evaluate the focus of resonance, such as
• oral,
• pharyngeal/laryngeal, or
• nasal.

Phonation

• voice onset/offset characteristics, such as
• delayed voice onset and
• quality of voice at onset
• ability to sustain voicing for appropriate phrasing during speech
• ability to demonstrate a strong and consistent rate of vocal fold valving during diadochokinesis

Rate of Speech

Rate of speech may be indirectly impacted by voice disorders. For instance, a patient with a voice disorder may deliberately slow rate of speech to compensate for a voice disorder and increase intelligibility. For reasons such as these, an SLP may consider assessment of rate of speech (e.g., via diadochokinetic rate assessment).

Instrumental Assessment

Laryngeal Imaging

Measures of structure and gross function (using videoendoscopy) and measures of vocal fold vibration during phonation (using videostroboscopy). Please see ASHA’s resource on Vocal Tract Visualization and Imaging for more information.

Acoustic Assessment

Objective measures of vocal function related to vocal loudness, pitch, and quality (Patel et al., 2018).

• Vocal amplitude
• habitual sound pressure level (SPL) in decibels (dB)—typical sound level of voice during connected speech
• minimum and maximum vocal SPL (dB)—softest and loudest sustainable phonation
• Vocal frequency
• mean vocal F0 in hertz (Hz)—average of the estimates of the F0 for acoustic signal recorded during connected speech
• vocal F0 standard deviation (Hz)—standard deviation of the estimates of the F0 for acoustic signal recorded during connected speech
• minimum and maximum vocal F0 (Hz)— F0 values for the lowest and highest pitched sustainable phonations
• Vocal signal quality
• vocal cepstral peak prominence (dB)—relative amplitude of the peak in the cepstrum that represents the dominant harmonic of the vocal acoustic signal (sustained vowels and connected speech samples)

Aerodynamic Assessment

Measures (using noninvasive procedures) of glottal aerodynamic parameters required for phonation.

• Glottal airflow
• average glottal airflow rate (L/sec or mL/sec)—estimated from oral airflow rate during vowel production
• Subglottal air pressure
• average subglottal air pressure (centimeters of water [cmH₂O] or kilopascals [kPa])—estimated for intraoral air pressure produced during repetition of stop consonants in syllable strings
• Mean vocal SPL and F0—extracted from simultaneously recorded acoustic signal; facilitates interpretation of airflow and air pressure measurements

SLPs should be aware of potential sources of error or impediments to recording quality during aerodynamic assessment. Sources of error may contribute to inaccurate data. These error sources include

• quality and calibration of instrumentation used, such as
  • a microphone,
  • a preamplifier,
  • analog-to-digital conversion (i.e., digital interface), and
  • software;
• consistent distance of sound source (voice) to microphone;
• acoustic qualities of room; and
• ambient noise (Patel et al., 2018; Švec & Granqvist, 2018).

Pediatric Voice Assessment Considerations

Although many of the same voice disorders may exist among children and adults, the following conditions tend to be unique to the pediatric population (Sapienza & Ruddy, 2009):

• Laryngomalacia—a congenital condition of the larynx of unknown etiology
  • This is the most common cause of infant inspiratory stridor.
  • The diagnosis of laryngomalacia is characterized by
    • inspiratory stridor,
    • immature laryngeal cartilage,
    • floppy epiglottis, and/or
    • foreshortened aryepiglottic folds.
• Laryngeal webbing—existence of membranous tissue that connects the two vocal folds
  • This occurs more frequently in the pediatric population during the 4th to 10th week of gestation.
  • This may cause airway blockage.
  • This may be acquired due to laryngeal trauma.
  • Dyspnea and inspiratory stridor are associated symptoms.
• Laryngeal cleft—a rare congenital condition that involves an opening between the larynx and the esophagus. Symptoms can include hoarseness, stridor, dysphagia, and coughing. Laryngeal clefts have four classification types based on the severity and extent of the cleft (Rahbar et al., 2006), as follows:
  • Type I—Interarytenoid deficit above the true vocal folds.
  • Type II—The cricoid lamina is involved; the cleft extends below the true vocal folds.
  • Type III—A total cricoid cleft that extends through the cricoid cartilage and may extend into the cervical trachea.
  • Type IV—A cleft that extends into the posterior thoracic trachea wall and may extend to the carina.
• Puberphonia—a functional voice disorder that may occur to male adolescents following a voice change during puberty that results in maintaining a high-pitched voice

Further information regarding laryngomalacia and laryngeal cleft may be found in ASHA’s Practice Portal page on Aerodigestive Disorders.

Intervention is conducted to achieve improved voice production and coordination of respiration and laryngeal valving. The ASHA Practice Portal page on Head and Neck Cancer addresses intervention aimed at acquisition of alaryngeal speech sufficient to allow for functional oral communication.

Intervention is designed to

• establish appropriate vocal hygiene routines/practices;
• capitalize on strengths and address weaknesses related to underlying structures and functions that affect voice production;
• improve self-awareness of voice quality and kinesthetic factors (e.g., tension);
• facilitate the individual’s activities and life participation by assisting the person in acquiring new communication skills and strategies;
• modify contextual factors to reduce barriers and enhance facilitators of successful communication and participation; and
• provide appropriate accommodations and other supports as well as training in how to use them.

Voice use within different settings should be considered when determining vocal needs and establishing goals. For example, vocal needs within the workplace may be different from those within the community (e.g., home and social settings).

Collaborating With Other Professionals

SLPs often team with otolaryngologists/laryngologists and other medical professionals (e.g., pulmonologists, gastroenterologists, neurologists, allergists, endocrinologists, and occupational medicine physicians) and, if appropriate, develop treatment plans to support the medical plan and to optimize outcomes. Collaboration with otolaryngologists/laryngologists is especially important to rule in or rule out underlying pathologies. SLPs can only diagnose functional abnormalities, and only otolaryngologists can diagnose organic pathologies (e.g., nodules, polyps, tumors).

Some individuals develop voice disorders in the absence of structural pathology (e.g., functional aphonia, muscle tension dysphonia, and mutational/functional falsetto) and may benefit from psychological counseling in addition to what can be provided by the SLP. Counseling, direct manipulation of the voice, and use of interview questions can be used to probe possible factors contributing to the voice problem. SLPs refer the individual to the appropriate health care professional(s) to address issues outside the SLP’s scope of practice (ASHA, 2016b).

See ASHA’s resources on collaboration and teaming and interprofessional education/interprofessional practice (IPE/IPP).

Treatment Approaches

Approaches can be direct or indirect, and SLPs often incorporate aspects of more than one therapeutic approach in developing a treatment plan.

Direct Approaches

Direct approaches focus on manipulating the voice-producing mechanisms (phonation, respiration, and musculoskeletal function) to modify vocal behaviors and establish healthy voice production (Colton & Casper, 2011; Stemple, 2000).

Indirect Approaches

Indirect approaches modify the cognitive, behavioral, psychological, and physical environments in which voicing occurs (Roy et al., 2001; Thomas & Stemple, 2007). Indirect approaches include the following two components:

• Patient education—discussing normal physiology of voice production and the impact of voice disorders on function; providing information about the impact of vocal misuse and strategies for maintaining vocal health (vocal hygiene).
• Counseling—identifying and implementing strategies such as stress management to modify psychosocial factors that negatively affect vocal health (Van Stan et al., 2015).

Therapeutic Plan

A therapeutic plan typically involves at least one direct approach and one or more indirect approaches based on the patient’s condition and goals. Some clinicians concentrate on directly modifying the specific symptoms of the inappropriate voice, whereas others take a more holistic approach, with the goal of balancing the physiologic subsystems of voice production—respiration, phonation, and resonance.

Clinicians may begin by

• identifying behaviors that are contributing to the voice problems, including unhealthy vocal hygiene practices such as
• shouting,
• talking loudly over noise,
• coughing,
• throat clearing, and
• poor hydration.
• implementing practices to reduce vocally traumatic behaviors (e.g., voice conservation) and healthy vocal hygiene practices such as
• drinking plenty of water and
• talking at a moderate volume.

Use of personal protective equipment (PPE) (i.e., face mask) can potentially cause increased strain on voice and perception of vocal effort (Ribeiro et al., 2020). Please see ASHA guidance to SLPs regarding aerosol generating procedures and the Resources section below for further information.

Pediatric Voice Treatment Considerations

There may be differences between treating voice disorders in adults and pediatrics due to differences in anatomy, etiology, and developmental level. According to Braden (2018), anatomical differences between pediatric and adult voice include the following:

• laryngeal size
• size of the vocal tract
• structure (pediatric vocal folds)
  • Pediatric vocal folds are shorter than adult vocal folds.
  • Pediatric vocal folds lack the five-layer structure until adolescence.
• structure (infant vocal folds)
  • Infant vocal folds are monolayer.
  • Infant vocal folds have hyaluronic acid distributed evenly (concentrated in adults).
  • Infant vocal folds have more fibroblasts than adults in the lamina propria.
• positioning of the larynx (McAllister & Sjölander, 2013)
  • The newborn larynx is located at approximately C4.
  • The adult larynx is located at approximately C6-C7.

As a child’s phonatory structures grow and develop, the respective speaking pitch decreases (decreased frequency of vocal tract formants and fundamental frequency). There is a rapid decrease in mean fundamental frequency in the first 3 years, with another significant change at puberty (McAllister & Sjölander, 2013). Abnormal voice changes may be monitored during adolescence as they may be indicative of a functional voice disorder such as puberphonia. Stridor should also be closely monitored in the pediatric population as it could potentially indicate a compromised airway (Theis, 2010).

Many treatment approaches used for adult populations may be considered for the pediatric population, although adaptations may be needed to meet each child’s developmental level (Braden, 2018). Comorbid developmental disorders such as expressive or receptive language deficits may further complicate treatment of voice in the pediatric population. Some children may not have an internal concept of normal versus abnormal voicing (Hooper, 2004) and, therefore, may have difficulty addressing dysfunction.

Another consideration is potential difficulties that may occur in obtaining treatment in the school-based setting. Challenges may include

• difficulty obtaining referrals to ENT/voice specialists,
• delays in scheduling pediatrician and/or ENT visits,
• difficulty accessing imaging and medical records,
• insurance coverage or payment for MD visits, and
• barriers in eligibility criteria and determining adverse effects on educational performance.

Please see Childes et al. (2017) for further consideration of barriers and challenges.

Treatment Options

The following subsections offer brief descriptions of general and specific treatments for individuals with voice disorders. They are organized under two categories: physiologic voice therapy (i.e., those treatments that directly modify the physiology of the vocal mechanism) and symptomatic voice therapy (i.e., those treatments aimed at modifying deviant vocal symptoms or perceptual voice components using a variety of facilitating techniques). The inclusion of any specific treatment approach does not imply endorsement by ASHA. For more information about treatment approaches and their use with various voice disorders, see Stemple et al. (2010).

Treatment selection depends on the type and severity of the disorder and the communication needs of the individual. Clinicians incorporate functional daily voice needs into goals that reflect inclusion and participation in home, work, and social communities. Linguistic features in some languages may influence the need for specific aspects of voice treatment, such as influences of tonal languages on resonance. In addition, consideration of individuals’ needs, such as gender and/or gender expression or use of regional accents, is an important aspect of goal development.

Physiologic Voice Therapy

Physiologic voice therapy programs strive to balance the three subsystems of voice production (respiration, phonation, and resonance) as opposed to working directly on isolated voice symptoms. Most physiologic approaches may be used with a variety of disorders that result in hyper- and hypofunctional vocal patterns. Below are some of the physiologic voice therapy programs, arranged in alphabetical order.

Accent Method

The accent method is designed to increase pulmonary output, improve glottic efficiency, reduce excessive muscular tension, and normalize the vibratory pattern during phonation. During therapy, the clinician may do one or more of the following tasks (Kotby et al., 1993; Malki et al., 2008):

• facilitate abdominal breathing by initially placing the patient in a recumbent position;
• use rhythmic vocal play with models of accented phonation patterns, which the patient then imitates; and/or
• transfer rhythms to articulated speech, initially being given a model and eventually progressing through reading, monologues, and conversational speech.

Conversation Training Therapy (CTT)

CTT focuses exclusively on voice awareness and production in patient-driven conversational narrative, without the use of a traditional therapeutic hierarchy. Grounded in the tenets of motor learning, CTT strives to guide patients in achieving balanced phonation through clinician reinforcement, imitation and modeling in conversational speech. CTT incorporates six interchangeable components (Gartner-Schmidt et al., 2016; Gillespie et al., 2019), as follows:

1. clear speech
2. auditory and kinesthetic awareness
3. negative practice/labeling
4. embedding basic training gestures into speech
5. prosody, projection, and pauses
6. rapport building

Expiratory Muscle Strength Training (EMST)

EMST improves respiratory strength during phonation. Increase in maximum expiratory pressure can be trained with specific calibrated exercises over time, thus improving the relationship between respiration, phonation, and resonance. EMST uses an external device to mechanically overload the expiratory muscles. The device has a one-way, spring-loaded valve that blocks the flow of air until the targeted expiratory pressure is produced. The device can be calibrated to increase or decrease physiologic load on the targeted muscles (Pitts et al., 2009).

Lee Silverman Voice Treatment (LSVT)

LSVT (Ramig et al., 1994) is an intensive treatment developed for patients with Parkinson’s disease. It is designed to maximize phonatory and respiratory function using a set of simple tasks. Individuals are instructed to produce a loud voice with maximum effort and to monitor the loudness of their voices while speaking. The effort that is involved generates improved respiratory support, laryngeal muscle activity, articulation, and even facial expression and animation. Using a sound-level meter, visual biofeedback may be provided to demonstrate the effort necessary to increase loudness. LSVT is provided by clinicians who are trained and certified in the administration of this technique.

Five basic principles are followed in LSVT, as follows:

• Individuals should “think loud.”
• Speech effort must be high.
• Treatment must be intensive.
• Patients must recalibrate their loudness level.
• Improvements are quantified over time.

Manual Circumlaryngeal Techniques

Manual circumlaryngeal techniques are intended to reduce musculoskeletal tension and hyperfunction by re-posturing the larynx during phonation. There are three main manual laryngeal re-posturing techniques, as follows:

• Push-back maneuver—place forefinger on the thyroid cartilage and push back to change the shape of the glottis.
• Pull-down maneuver—place thumb and forefinger in the thyrohyoid space and pull the larynx downward.
• Medial compression and downward traction—place thumb and forefinger in the thyrohyoid space and apply medial compression.

Applying these maneuvers during vocalization allows the individual to hear resulting changes in voice quality (Andrews, 2006; Roy et al., 1997). Care is taken when employing these techniques, as some patients report discomfort.

Phonation Resistance Training Exercises (PhoRTE)

PhoRTE (Ziegler & Hapner, 2013) was adapted from LSVT and consists of four exercises, as follows:

• producing /a/ with loud maximum sustained phonation
• producing /a/ with loud ascending and descending pitch glides over the entire pitch range
• producing functional phrases using a loud and high (pitched) voice
• producing the same functional phrases using a loud and low (pitched) voice

Individuals are reminded to maintain a “strong” voice throughout these treatment exercises. PhoRTE has a less intensive intervention schedule than LSVT. PhoRTE also differs in that it combines both loudness and pitch when producing phrases (i.e., loud and low pitch, loud and high pitch). Use of PhoRTE has been studied in adults with presbyphonia (aging voice) as a way to improve vocal outcomes (e.g., decrease phonatory effort) and increase voice-related quality of life (Ziegler et al., 2014).

Resonant Voice Therapy

Resonant voice therapy uses a continuum of oral sensations and easy phonation, building from basic speech gestures through conversational speech. Resonant voice is defined as voice production involving oral vibratory sensations, usually on the anterior alveolar ridge or lips or higher in the face in the context of easy phonation. The goal of resonant voice therapy is to achieve the strongest, “cleanest” possible voice with the least effort and impact between the vocal folds to minimize the likelihood of injury and maximize the likelihood of vocal health (Stemple et al., 2010). The program incorporates humming and both voiced and voiceless productions that are shaped into phrase and conversational productions (Verdolini, 1998, 2000).

Stretch and Flow Phonation

Stretch and flow phonation—also known as Casper-Stone Flow Phonation—is a physiological technique used to treat functional dysphonia or aphonia (Stone & Casteel, 1982). It focuses on airflow management and is used for individuals with breath-holding tendencies. Individuals are instructed to focus on a steady outflow of air during exhalation. Various biofeedback methods are used, including placing a piece of tissue in front of the mouth or holding one’s hand in front of the mouth to monitor airflow. Voicing is introduced once the individual masters continuous airflow during exhalation. As such, this technique produces a breathy voice quality and a slowed speaking rate. Eventually, this voice quality is carried into trials with spoken words and phrases, and the breathiness is gradually reduced.

Flow phonation (Gartner-Schmidt, 2008, 2010) is a hierarchical therapy program designed to facilitate increased airflow, ease of phonation, and forward oral resonance. It was modified from stretch and flow phonation by eliminating the “stretch” component, which reduced the rate of speech in the original therapy.

Vocal Function Exercises (VFEs)

VFEs are a series of systematic voice manipulations designed to facilitate return to healthy voice function. VFEs work to strengthen and coordinate laryngeal musculature and improve efficiency of the relationship among airflow, vocal fold vibration, and supraglottic treatment of phonation (Stemple, 1984). Sounds used in training are specific, and correct production is encouraged. VFEs consist of four exercises—warm-up, stretching, contracting, and power exercises. Exercises are completed twice a day (morning and evening) in sets of two. Maximum phonation time goals are set on the basis of individual lung capacity and an airflow rate of 80 mL/sec. Individuals are advised to use a soft, engaged tone and are trained to use a semi-occluded vocal tract (SOVT) without tension during voice productions.

Symptomatic Voice Therapy

Symptomatic voice therapy focuses on the modification of vocal symptoms or perceptual voice components. Symptomatic voice therapy assumes voice improvement through direct symptom modification using a variety of voice facilitating techniques (Boone et al., 2010) that are either direct or indirect. Symptoms to be addressed may include

• pitch that is too high or too low,
• voice that is too soft or too loud,
• breathy phonation,
• hard glottal attacks, or
• glottal fry.

Amplification

Amplification devices such as microphones can be used to increase voice loudness in any situation that requires increased volume (e.g., when speaking to large groups or during conversation when the individual’s voice is weak). As such, voice amplification can function as a supportive tool or as a means of augmentative communication. It can help prevent vocal hyperfunction that may be a result of talking at increased volume or for extended periods of time.

Auditory Masking

Auditory masking is used in cases of functional aphonia/dysphonia and often results in changed or normal phonation. Individuals are instructed to talk or read passages aloud while wearing headphones with masking noise input. Using a loud noise background, the individual often produces voice at increased volume (Lombard effect) that can be recorded and used later in treatment as a comparison (e.g., Adams & Lang, 1992; Brumm & Zollinger, 2011).

Biofeedback

Biofeedback is the concept that self-control of physiologic functions is possible given external monitoring of internal bodily state. Biofeedback may be kinesthetic, auditory, or visual and is intended to provide clear and reliable information in response to alterations in voice production. Thus, patients may make real-time adjustments regarding vocal pitch, loudness, quality, and effort. Ideally, biofeedback helps increase awareness of physical sensations with respect to respiration, body position, and vibratory sensation. This awareness may help individuals understand physiological processes when generating voice.

Chant Speech

Chant speech uses a rhythmic, prosodic pattern as a template for spoken utterances. It is used in therapy to help reduce phonatory effort that results in vocal fatigue and decreased phonatory capabilities. Chant speech requires pitch fluctuations and coordination of respiratory, phonatory, and resonance subsystems. Speakers habituate to these more efficient vocal patterns. The increased lung pressure required for these tasks may also decrease reliance on laryngeal resistance and reduce fatigue (e.g., McCabe & Titze, 2002).

Confidential Voice

Confidential voice is designed to reduce laryngeal tension/hyperfunction and increase airflow (Casper, 2000). The individual begins with an easy and breathy vocal quality and builds to normal voicing without decreasing airflow. This technique is intended to address excessive vocal tension and to facilitate relaxation in the muscles of the larynx.

Inhalation Phonation

Inhalation phonation is used to facilitate true vocal vibration in the presence of habitual ventricular fold phonation, functional aphonia, and/or muscle tension dysphonia. Individuals produce a high-pitched voice on inhalation. Upon inhalation voicing, the true vocal folds are in a stretched position, suddenly adducted, and in vibration. Upon exhalation, patients try to achieve a nearly matched voice. This approach eases the way to gaining true vocal fold vibration.

Posture

The patient is instructed in the technique of sitting with upright posture and with the shoulders in a low, relaxed position to facilitate voice production with less effort. Collaboration with a physical therapist or an occupational therapist may be necessary with some patients.

Relaxation

In cases of vocal hyperfunction, a variety of relaxation techniques may be useful as a tool to reduce both whole-body and laryngeal area tension. The goal of these techniques is to reduce effortful phonation. Frequently used techniques include progressive muscle relaxation (slowly tensing and then relaxing successive muscle groups), visualization (forming mental images of a peaceful, calming place or situation), and deep breathing exercises.

Semi-Occluded Vocal Tract (SOVT) Exercises

SOVT exercises involve narrowing at any supraglottic point along the vocal tract in order to maximize interaction between vocal fold vibration (sound production) and the vocal tract (the sound filter) and to produce resonant voice.

Cup bubble, also known as Lax Vox, is an aerodynamic building task aimed at improving the ability to sustain phonation while speaking. It is done by having a patient blow air initially into a cup of water without voice. Voicing can be added for subsequent trials, and in time, pitch can be altered across and within trials. Eventually, the cup is removed during voicing, and the phonation continues. These exercises are thought to widen the vocal tract during phonation and reduce tension in the vocal folds. Biofeedback increases the individual’s awareness of their healthy voice production (e.g., Denizoglu & Sihvo, 2010; Simberg & Laine, 2007).

Straw phonation is one of the most frequently used methods to create semi-occlusion in the vocal tract (Titze, 2006). Narrowing the vocal tract increases air pressure above the vocal folds, keeping them slightly separated during phonation and reducing the impact collision force. To accomplish this, the individual semi-occludes the vocal tract by phonating through a straw or tube. Resistance can be manipulated by varying the length and diameter of the straw or immersing the opposite end of the straw in water. Individuals practice sustaining vowels, performing pitch glides, humming songs, and transitioning to the intonation and stress patterns of speech. Eventually, use of the straw is reduced and eliminated.

Lip trills can be used to create semi-occlusion at the level of the lips. This technique involves a smooth movement of air through the oral cavity and over the lips, causing a vibration (lip buzz), similar to blowing bubbles underwater. Often, the trills are paired with phonation and pitch changes. The focus is to improve breath support and produce voicing without tension.

Twang Therapy

Twang therapy is used for individuals with hypophonic voice. It involves the narrowing of the aryepiglottic sphincter using a “twang” voice to create a high-intensity voice quality while maintaining low vocal effort (Lombard & Steinhauer, 2007). The desired outcome is decreasing phonatory effort and increasing vocal efficiency.

Yawn-Sigh

This facilitating technique uses the natural functions of yawning and sighing to overcome symptoms of vocal hyperfunction (e.g., elevated larynx and vocal constriction). The technique is intended to lower the position of the larynx and subsequently widen the supraglottal space in order to produce a more relaxed voice and encourage a more natural pitch.

Treatment Considerations: Telepractice and Telecommuting

SLPs should take appropriate measures whether services are being delivered in-person or through telepractice. Teletherapy may not provide as reliable sound quality as in-person. Therefore, additional equipment (e.g., microphones) can enhance vocal quality while reducing vocal strain. Additionally, SLPs should take into consideration whether or not the patient is telecommuting for their profession, as there is some emerging research regarding effects of telecommunications on voice (Tracy et al., 2020).

Please see ASHA’s Practice Portal page on Telepractice and ASHA’s Telepractice Evidence Map.

Treatment Considerations: Rehabilitation of Singing Voice

SLPs often work with singers to treat vocal function issues; however, providing this therapy requires additional training/education. Interdisciplinary treatment may involve

• an otolaryngologist,
• an SLP, and/or
• a singing teacher.

Please see The Role of the Speech-Language Pathologist, the Teacher of Singing, and the Speaking Voice Trainer in Voice Habilitation for further information.

Service Delivery

Refer to the Service Delivery section of the Voice Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.

In addition to determining the type of speech and language treatment that is optimal for individuals with voice disorders, SLPs consider other service delivery variables—including format, provider, dosage, and timing—that may affect treatment outcomes.

• Format—the structure of the treatment session (e.g., group vs. individual; direct and/or consultative).
• Provider—the person offering the treatment (e.g., SLP, trained volunteer, caregiver).
• Dosage—the frequency, intensity, and duration of service. Clinicians consider the unique needs of each patient and the nature of the voice disorder in determining appropriate dosage for therapy. Some voice therapy programs will have specific dosage parameters. See De Bodt et al. (2015) for a summary of international practices regarding temporal variables (dosage and frequency) in voice therapy.
• Timing—when intervention is conducted relative to the diagnosis.
• Setting—location of treatment (e.g., home, community-based, work).

ASHA Resources

• ASHA Guidance to SLPs Regarding Aerosol Generating Procedures
• ASHA CAPE-V Form
• ASHA Code of Ethics
• ASHA Scope of Practice in Speech-Language Pathology
• Consumer Resource Related to Voice Disorders
• Cultural Competence
• Definitions of Communication Disorders and Variations
• Gender-Affirming Voice and Communication Change for Transgender and Gender-Diverse People
• Graduate Curriculum on Voice and Voice Disorders [PDF] (Developed by ASHA Special Interest Group 3: Voice and Voice Disorders)
• Multicultural Issues in the Treatment of Voice Disorders
• Preferred Practice Patterns for the Profession of Speech-Language Pathology
• The Role of the Speech-Language Pathologist, the Teacher of Singing, and the Speaking Voice Trainer in Voice Habilitation
• States with Specific Instrumental Assessment Requirements
• Using Masks for In-Person Service Delivery During COVID-19 Pandemic: What to Consider
• Voice and Communication Services for Transgender and Gender Diverse Populations

Other Resources

This list of resources is not exhaustive, and the inclusion of any specific resource does not imply endorsement from ASHA.

• American Academy of Otolaryngology–Head and Neck Surgery: Clinical Practice Guidelines
• The National Center for Voice and Speech
• National Institute on Deafness and Other Communication Disorders
• National Spasmodic Dysphonia Association
• Speech-Language & Audiology Canada: Covid-19 changes the way many people use their voices
• The Voice Foundation
• World Voice Day

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Acknowledgements

Content for ASHA's Practice Portal is developed through a comprehensive process that includes multiple rounds of subject matter expert input and review. ASHA extends its gratitude to the following subject matter experts who were involved in the development of the Voice Disorders page:

• Julie M. Barkmeier-Kraemer, PhD, CCC-SLP
• Jennifer N. Craig, MS, CCC-SLP
• Archie B. Harmon, PhD, CCC-SLP
• Robert E. Hillman, PhD, CCC-SLP
• Barbara Jacobson, PhD, CCC-SLP
• Rita R. Patel, PhD, CCC-SLP
• Bari Hoffman Ruddy, PhD, CCC-SLP
• Joseph C. Stemple, PhD, CCC-SLP
• Yumi A. Sumida, MS, MFA, CCC-SLP
• Kristine Tanner, PhD, CCC-SLP
• Shannon M. Theis, PhD, CCC-SLP
• Miriam R. van Mersbergen, PhD, CCC-SLP
• Laura Purcell Verdun, MA, CCC-SLP

In addition, ASHA thanks the American Academy of Otolaryngology-HNS Speech, Voice and Swallowing Committee members and ASHA Special Interest Division 3, Voice and Voice Disorders Steering Committee members whose work was foundational to the development of this content.

The members of the AAO-HNS Speech, Voice and Swallowing Committee included Robert Sataloff, Jonathan Aviv, Mary Beaver, Alison Behrman (ASHA representative), Mark Courey, Glendon Gardner, Norman Hogikyan, Christy Ludlow (ASHA representative), Roger Nuss, Clark Rosen, Mark Shikowitz, Robert Stachler, Lee Akst, and Susan Sedory Holzer (staff liaison).

The members of the ASHA Special Interest Division 3, Voice and Voice Disorders Steering Committee included Leslie Glaze (coordinator), Bernice Klaben, Lori Lombard, Mary Sandage (associate coordinator), Susan Thibeault, and Michelle Ferketic (ex officio). Celia Hooper, vice president for professional practices (2003–2005), served as monitoring vice president for ASHA.

Citing Practice Portal Pages

The recommended citation for this Practice Portal page is:

American Speech-Language-Hearing Association. (n.d.). Voice Disorders. (Practice Portal). Retrieved month, day, year, from www.asha.org/Practice-Portal/Clinical-Topics/Voice-Disorders/.