From the Desk of Ann Kummer
Evidence-based practice (EBP) is a conscientious, problem-solving approach to clinical practice that incorporates the integration of clinical expertise, evidence (gathered from both scientific literature and clinical observations), and the values and preferences of the client and their caregivers. Speech pathologists who consider these three components of evidence-based practice when making clinical decisions will be most effective in treating individuals with communication disorders.
Because most speech pathologists do not specialize in voice disorders, it is particularly important to consider the evidence for specific therapeutic strategies when working with an individual with a voice disorder. Therefore, I’m particularly excited to introduce this 20Q article to you, written by Ryan Branski and Shirley Gherson, who are experts in considering research and voice science when treating voice disorders.
Ryan C. Branski, PhD is the Howard A. Rusk Associate Professor of Rehabilitation Research and the Vice-Chair for Research in Rehabilitation Medicine at the NYU Grossman School of Medicine. He also holds appointments in Otolaryngology-Head and Neck Surgery in the school of medicine and Communicative Sciences and Disorders in the Steinhardt School of Culture, Education, and Human Development at New York University. His laboratory program is funded by the National Institutes of Health and he is one of only a few investigators to be named Fellow of the American Speech-Language Hearing Association, the American Laryngological Association, and the American Academy of Otolaryngology-Head and Neck Surgery.
Shirley Gherson, MS, CCC-SLP is a speech pathologist and voice specialist at the NYU Voice Center. She is on faculty at the Communication Sciences and Disorders Program at NYU Steinhardt where she has developed curriculum for and teaches voice disorders. She also holds an appointment as a clinical assistant professor in Otolaryngology-Head and Neck Surgery at NYU Grossman School of Medicine. Ms. Gherson has over 20 years of experience working exclusively with voice and airway disorders, and has authored and co-authored numerous textbook chapters and research articles on the subject.
This article addresses real-life scenarios speech pathologists often come across when providing therapy to a patient with a voice disorder. Evidence-based treatment strategies and principles are discussed with particular focus on application of research.
Now…read on, learn, and enjoy!
Ann W. Kummer, PhD, CCC-SLP, FASHA, 2017 ASHA Honors
Browse the complete collection of 20Q with Ann Kummer CEU articles at www.speechpathology.com/20Q
20Q: Putting Research into Practice:
Application of Voice Science In the Therapy Room
After this course, readers will be able to:
- Understand best practices for referral requirements, as well as occupational risk factors, and broad organization of therapy activities.
- Describe the scientific underpinnings behind vocal hygiene recommendations (e.g., hydration, voice rest, and reflux counseling), SOVT exercises, and carryover principles.
- Describe the impact of sensory processing and integration challenges on communication skills
1. What do I need to know and do before I start voice treatment?
In addition to knowledge of vocal anatomy and physiology as well as voice therapy exercises, aspects of a referral guide the direction in which you take your patient in therapy. First and foremost, it is essential that your patient undergoes laryngeal examination in which the vocal folds are visualized by a trained ENT specialist. Although our ears can provide plenty of information as to the quality of the sound, we cannot decipher the root pathologic cause. At minimum, a lack of laryngeal imaging can set us up for frustration if the vocal lesion is not treatable by therapy alone. In the worst-case scenario, our treatment may delay the diagnosis of a more serious disease process or even cancer. Be sure your patient has had an exam before initiating treating.
Other information that can help guide your therapy plan is the timing of voice change; is being treated for an acute injury (sudden onset like a vocal hemorrhage) or a chronic injury (which develops over time). In acute injuries, you typically want to spend more time counseling to reduce voice use and avoid vocally aggressive activities. With chronic injuries, the focus is typically geared toward behavioral change of speaking habits. In addition to behavioral therapy, it is also helpful to know if surgery is being considered. If so, it can be helpful to set up expectations during pre-operative therapy and also discuss plans for post-operative voice rest and recovery. Lastly, medical treatments (e.g., steroids, anti-reflux treatment, anti-histamines) can also change your counseling strategies.
To capture outcome data, document the patient’s self-assessment of their voice disorder with a quality of life measure. These surveys are quick to administer and provide important context for the voice disorder in each patient. Some examples of quality of life measures that are available include: Voice Handicap Index (VHI; VHI-10), Voice Related Quality of Life (VRQOL), Evaluation of the Ability to Sing Easily (EASE), and Vocal Fatigue Index (VFI). There are additional measures designed and validated for children as well.
Finally, have several therapeutic maneuvers ready to try out with the patient during the evaluation. These tasks may improve the patient’s sense of reduced vocal effort or increase awareness of resonance. A brief period of trial therapy can be a powerful prognostic indicator of how your patient will fare in therapy and can also give you a sense of where to begin with treatment (Litts et al, 2015).
2. OK, so the patient is in front of me. How do I start?
Once you have a clear sense of the patient’s diagnosis and baseline measures, start with a conversation to establish specific goals the patient would like to achieve in therapy. This process ensures that your therapy activities align with what is meaningful and relevant to the patient. For example, therapy will look very different for someone who wants to be able to read bedtime stories to their grandchildren compared to a patient who must project their voice to teach 5 hours of group fitness classes. If the patient struggles with generating goals, you may choose to use motivational interviewing strategies such as reflecting or summarizing your patient’s thoughts throughout the conversation and using open-ended questions. These strategies have the added benefit of allowing you to develop rapport and establish a trusting and mutually respectful relationship.
Once goals have been established, you want to think about two broad categories of therapy activities; indirect and direct intervention. Indirect treatment encompasses education and counseling and direct treatment includes any exercise directly applied to the patient (Van Stan et al, 2015). The table below provides examples of activities in each category:
Counseling on vocal hygiene
Stretching and massage to release muscle tension
Education provided on the patient’s diagnosis
Patient training for increased airflow or resonance in vocal production
Use of motivational interviewing to enhance patient motivation for setting up a consistent home exercise program
Exercises that train the patient to carryover concepts of airflow and resonance into conversation.
3. Are there particular professions that are inherently more susceptible to voice disorders?
Yes, some occupations are more at risk for developing a voice disorder than others. This risk may depend on the amount of talking required (vocal load), the intensity of voice use, and/or the work environment (Phyland & Miles, 2019). High-risk professions include, but are not limited to teachers, performers, clergy, lecturers, receptionists, and group fitness instructors. Teachers in particular are highly susceptible to voice problems given the sheer amount of prolonged and projected voice use in the classroom (Roy et al, 2004). If you are unsure of your patient’s vocal demands, map out their daily activities. It can be an eye-opening experience, and also provide guidance as to how much of the acquired voice problem may be associated with your patient’s vocational voice use and requirements.
4. So if I have a patient who has a job that requires a significant amount of talking, should I just have them rest their voices as much as possible at home? How do I work around the issue of a patient getting paid to use their voice constantly at work?
Professions requiring high levels of voice use are growing, so this is a very relevant and important question for speech pathologists to consider. Asking a patient to rest their voice for long periods of time may not be possible. In addition, the patient may already feel increasingly limited by their voice disorder both at work and in social settings. Rather, the patient should be encouraged to alter their style of speaking and develop more efficient use of voice with less stress on the mechanism. This alteration should enhance vocal stamina and quality, while reducing stress on the vocal injury. A multitude of voice therapy strategies train the patient to enhance airflow and resonance in the context of speech. In addition, training supportive strategies such as modifying the environment (e.g., lowering background noise, slowing down, and/or using a personal amplification device) can also be helpful in facilitating recovery in spite of a vocally taxing job.
5. Some of my voice patients have described themselves as “very talkative.” Is an extroverted personality more likely to cause a voice disorder?
Outside of vocational voice use, social voice use can also contribute to an ongoing voice problem. Research by Nelson Roy and Diane Bless (2000) suggests that the degree to which a person acts out his/her/their own personality traits can influence the degree and type of voice disorder that develops. For example, a highly extroverted patient with vocal nodules may be more inclined to over-express their feelings in social settings compared to a patient who is more inhibited. These findings not mean that all talkative people with vocal nodules are extroverts, or that all extroverts will have voice problems. Understanding the tendencies of your patient’s personality may allow you to tailor the approach to behavioral change to the patient’s natural inclinations. For example, training your patient to use a soft, gentle voice and listen more, may be a futile and frustrating endeavor for a naturally exuberant and extroverted patient (van Mersbergen, 2011).
6. Should I be covering vocal hygiene with all of my patients?
The topic of vocal hygiene is a familiar one to most speech pathologists. Drink plenty of water, avoid throat clearing and coughing, and reduce caffeine intake are commonly recommended. Although studies support the efficacy of vocal hygiene training as a preventative measure (Pasa et al., 2007), most research points towards the need for additional direct intervention (e.g., training voice exercises) in patients with voice disorders (Behrman et al, 2008).
With this in mind, choose to address only the most relevant areas of vocal hygiene to your patient. Allocating time to cover all areas of vocal hygiene may not only be irrelevant to the patient’s needs, but also take up valuable time that could otherwise be spent on direct rehabilitation.
7. How about voice rest? My patient is a school teacher with vocal nodules. I've been trying to get my patient to rest their voice as much as possible.
Voice rest is one of the most widely used treatment strategies to address voice disorders, but is not universally beneficial depending on the circumstances. Two types of voice rest have been described; complete (no voice whatsoever) and relative (only speaking when absolutely necessary and avoiding phonotraumatic activities). Complete voice rest is most helpful following an acute injury or directly after surgery (Sulica & Behrman, 2003). Beyond these two situations, data does not support voice rest for more chronic injuries (like vocal nodules, polyps, or cysts), which develop over time with maladaptive muscle patterns. In these cases, current literature points towards increased benefit from establishing improved coordination of the voice with brief periods of voice rest following heavy voice use (Ishikawa & Thibeault, 2010). In addition, exciting data also suggest the potential for low impact, high amplitude vocal fold vibration (e.g., resonant voice) to actually reduce vocal fold inflammation, similar to exercises performed by physical therapists for orthopedic injuries (Abbott et al, 2012).
8. I always make sure to talk about the importance of drinking water. I have my patients track how much water they are drinking since I know it's important to heal their voice. Right?
Anecdotally, we know that being well hydrated can reduce symptoms of effort and dryness, however to date there is no specific evidence that clearly demonstrates the therapeutic effect of increased hydration on the voice. Systemic and surface hydration improve objective voice measures, however the underlying mechanism of improved vocal function is still unknown (Hartley & Thibeault, 2014). Certainly, patients should be encouraged to hydrate, but hydration alone is not sufficient to treat an injured voice. Voice disorders are most often related to vocal misuse and compensatory muscle tension. Although improved vocal fold hydration can help to enhance the health of the vocal fold tissue, drinking water won’t address the functional aspects underlying the voice disorder.
9. OK, then what about reflux? I know that reflux causes hoarseness and many of my patients come in with that diagnosis. Should I be going through dietary modifications?
Reflux, more specifically laryngo-pharyngeal reflux, has been increasingly implicated as the cause of dysphonia to the extent that empiric treatment of hoarseness with reflux medication has become a popular trend. However, caution should be taken when the patient has not responded to medical treatment, or more disturbingly, if the patient has not had a thorough medical examination to visualize the vocal folds. A study by Rafii et al (2014), found voice pathology in nearly all patients examined with the incoming diagnosis of laryngopharyngeal reflux. Schneider et al (2016) found that the evidence linking reflux and subsequent voice problems to be insufficient.
If your patient has reflux diagnosed by the appropriate medical professionals, and require dietary modifications, counseling towards dietary and behavioral modifications can be helpful. Given the overwhelming number of dietary restrictions, collaborate with your patient to identify and address 3-4 of their most egregious symptom-inducing foods or behaviors.
10. My patients often ask me whether vocal exercises will strengthen their voice. Is that actually what’s happening?
The voice is the product of three subsystems; respiration, phonation, and resonance that all work together in a coordinated fashion. Our work as speech pathologists is to ensure these subsystems are well balanced and result in efficient voice production (improved sound quality with less effort). Given the difficulty in studying intrinsic laryngeal muscles, the specific effects of training on these muscles are unknown. However, it is likely that the process by which the patient’s voice gets “stronger” is through improved coordination of the subsystems and not muscle hypertrophy (Johnson & Sandage, 2019).
11. I’ve heard a lot about SOVT exercises. What are they and how do they work?
SOVT is the acronym for Semi-Occluded Vocal Tract. This approach implies that the patient is partially obstructing airflow while voicing. This obstruction may be achieved by narrowing the vocal tract or vocalizing through an articulation (e.g., humming or protruding the lips on /u/). Many therapists also use external instruments to change the shape of the vocal tract and enhance the effect of SOVT (e.g., straw, kazoo, cup, or straw in water). A number of physiologic benefits to this strategy have been reported. However, simply stated, SOVT increases the level of back-pressure in the vocal tract, which helps to “unpress” the vocal folds and reduce collision forces between the vocal folds. SOVT also enhances the sensation of resonance (via vibrotactile sensations) and allows for the experience of vocalizing with reduced effort (Rosenberg, 2014). This feedback makes SOVT exercises ideal for training and rehabilitation of a patient with a voice disorder.
12. Does it matter which SOVT exercise I use?
SOVT exercises can differ by method of production, as mentioned above, but they are largely differentiated by the amount of backpressure presented to the vocal tract. For example, vocalizing through a small straw will produce increased intra-oral pressure compared to a larger straw or lip trills. In an article explaining SOVT postures, Rosenberg (2014) provides a hierarchy of SOVT exercises, rank-ordering them from high to low back pressure. It is important to note that the choice of whether to use an SOVT with a higher vs lower level of back pressure depends on the response of the patient. Ideally, the patient should feel reduced vocal effort and increased vibrotactile sensations (Maxfield et al, 2015).
More recent studies have looked at the application of semi-occluded face masks to allow for the SOVT effect during connected speech (Mills et al, 2017; Awan et al, 2019).
SOVT postures are primarily used to ease stress on the voice and encourage the patient to rely more on the “source-filter” interaction to boost acoustic power. The theoretical underpinnings are that the semi-occlusions increase the interaction between the source (vocal fold vibration) and vocal tract by increased intra-glottal and supraglottal pressure (Rosenberg, 2014). Observational studies found that SOVT exercises produced a lower laryngeal position, wider pharynx at rest, and the sensation of reduced effort as well as improved voice quality (Guzman et al, 2013).
13. SOVT exercises sound quite powerful! Is that all I need to have my patients do for rehabilitation?
Despite the rapid increase in popularity of SOVT exercises, they do not directly influence the rehabilitation of the voice in the context of speech and/or singing. Lip trills and humming will not necessarily result in improved voice during speech or singing. The principle of specificity, or contextual relevance in motor learning theory accounts for this limitation. The theory posits that, in order for a new skill to be learned, one must practice that skill in a setting that most resembles the target activity (Gartner-Schmidt et al, 2015). For example, if your goal is to increase resonance during conversation, you must provide opportunities for the patient to apply this skill during conversation.
The development of Conversation Training Therapy (Gartner-Schmidt et al, 2015; Gillespie et al, 2019) directly addresses this issue by implementing conversation-based techniques as the sole focus of therapy. This novel approach trains the patient to adjust and improve their voice in the context of conversation, and in place of traditional prescriptive voice exercises. Recent efficacy data (Gillespie et al, 2019) comparing CTT to traditional models of voice therapy found that CTT resulted in greater improvement in perceived voice handicap over a shorter period of time with a significantly reduced number of sessions until discharge.
Although SOVT exercises are remarkably helpful, they must not be used in place of carryover exercises, where a patient practices application of a target skill.
14. Is voice therapy different when I’m working with a vocal performer?
Yes, performers, such as singers, actors, and voice-over artists use their voices with much greater variability of pitch, loudness control, and agility. Given the level of vocal training, skill, and stamina required of a performer, this cohort of patients have been compared to athletes (Sloggy et al, 2019). Even the most subtle change to the voice can result in significant limitations in performance (Petty, 2019). However, these symptoms may not be perceived in speech or more structured vocal tasks. Common complaints may include vocal fatigue, vocal instability (especially in register transitions or while singing softly), and loss of pitch range, to name a few (Pestana et al, 2017). A case history must account for singing training, style of music, and environmental factors in performance. In addition, non-performance vocal activities should be documented. With unpredictable schedules, performers are more apt to take jobs that allow for greater flexibility such as food service/bartending or fitness instruction. Both can be extremely taxing on the voice. Finally, from the standpoint of treatment skills and competence, it is important to have specialized training in working with performers before you attempt to treat performance-related vocal injuries.
15. Is voice therapy different when I’m working with a child?
A growing body of literature supports the efficacy of voice therapy for children. However, children with voice disorders should not be treated like adults with voice disorders. Both anatomy and physiology differ as well as cognitive skills based on stages of development. Children have smaller larynges that sit higher in the throat, and have undeveloped or immature biological structure of the vocal folds. Treatment of the very young (ages 2-5yrs) is consistent with models in early-intervention that use play-based strategies of modelling, mirroring, and training increased awareness of vocal quality, volume, and pitch (Braden & Verdolini, 2018). Young children are capable of learning SOVT exercises and general concepts of “easy” vs “pushy” voice, however this learning is best accomplished in the context of guided play. Older children may be able to engage in more formal therapy in a clinic, however as with young children, collaboration with parents and/or caregivers is critical to establish a home treatment program to ensure long-term success (Braden et al, 2018). School-aged children are avid learners and imitators, however the language and context in which they learn concepts and techniques of voice therapy must be adjusted to correspond with their cognitive level (Braden & Verdolini, 2018). Visual supports, stories, and tactile cues are particularly helpful. The use of role playing to reinforce strategies in conversation can also be both fun and motivational.
16. How about with the geriatric population? Are there particular considerations with patients 65 yrs or older?
The geriatric population is unique in several ways that may alter the course of voice therapy. Age related changes to the voice, known as presbyphonia, are typically characterized by loss of viscoelasticity of the vocal fold tissue as well as atrophy of the thyroarytenoid muscles leading to glottic insufficiency. Patients typically present with hoarseness, weakness, and/or unsteady voicing (Lenell et al, 2019). Although other co-existing diagnoses may emerge, voice therapy for this particular diagnosis is considered to be the most effective first line of treatment. Treatment programs that are most effective for vocal atrophy with target increased glottic closure. Several voice interventions have demonstrated improved outcomes specifically for presbyphonia, including Vocal Function Exercises, Phonation Resistance Training Exercises (PhorTe), and Lee Silverman Voice Treatment (Bradley et al, 2014; Ziegler et al, 2014). These approaches use the principle of overload in exercise physiology to require the phonatory system work harder than when compared to typical speech. Overload is reflected in maximal vocal function tasks and systematically training increased volume.
17. Now that I know what to do in therapy, how frequently should the patient see me for treatment?
Traditionally, voice therapy is performed once a week for an average of about 6-12 sessions. The number of sessions can vary based on diagnosis, patient adherence, and the skill set of the therapist, among other factors. More recently, the concept of high intensity voice therapy has been suggested as a service delivery model to improve voice outcomes given the low levels of patient adherence and high rate of attrition (Meerschman et al, 2019). The concept proposes increased session frequency over a shorter period of time (“massed practice”) to support motor learning and generalization of techniques. The Lee Silverman Voice Treatment model of 4 sessions per week for 4 weeks is an example of high intensity training with excellent short term and long-term outcomes (Thompson, 2001). More recent publications looking at massed practice models vs traditional models for patients with functional voice disorders and organic vocal lesions found no significant differences in functional outcome measures between groups (Wenke et al, 2014). Given the benefits of a shorter time commitment with improved patient adherence, it may make sense to consider this service delivery model in your practice.
18. What if my schedule doesn’t allow for high-intensity training for my patients? How can I best support my patient in their home practice program between therapy sessions?
If your schedule does not allow for increasing the frequency of therapy, you will need to ensure that the patient is confident and motivated to pursue a home exercise program independently. Patients find home-practice difficult as they are required to remember instructions, independently judge the accuracy of the exercise, and know how and when to apply voice techniques to conversation (van Leer & Connor, 2010). However, there are several approaches that can In a study by van Leer and Connor (2015), patients were twice as likely to practice with higher levels of confidence and greater levels of generalization when they were provided with videos of their exercises compared to a written descriptions. Consider having the patient record you doing the exercises, or record themselves. Recording the patient in therapy has the added benefit of reinforcing self-efficacy in that they are watching themselves successfully complete the exercise (van Leer & Connor, 2015).
You can also increase patient adherence to practicing outside of the therapy room by outlining when, where, and for how long the patient will carry out the exercises. Planning should be collaborative with chosen exercises that are relevant to the patient’s unique needs and goals. Obstacles to consider when planning home practice include; finding a place and a time to practice, remembering to practice, knowing how to practice, and motivation. It can also help to ensure that the patient feels the exercises are relevant to their problem, and that they are confident in the process.
Finally, always ensure that you build in opportunities for the patient to practice application of their techniques (Zeigler et al, 2014). More specifically, choosing the activity (e.g., first conversation of the day at work, reading to a child), specifying the timing of carryover (e.g., 3-5 minutes of focused attention to the technique in the context of a conversation), and being deliberate about what technique or strategy they will use (e.g., slowed pacing, increased resonance, increased airflow, etc).
19. My patient completed voice therapy and was doing great, but when they went back to the ENT for a follow-up their vocal nodules were still there! What happened?
A lack of resolution of voice pathology can be frustrating, leading some patients to believe therapy was ineffective. However, a number of factors may account for this lack of resolution. A recent study examined the effects of steroid treatment in patients with chronic phonotraumatic lesions and found no differences between the steroid and placebo groups (Amin et al, 2019). Collectively, in a group of 27 patients receiving a full course of voice therapy, only a small percentage of patients presented with improved laryngeal appearance, despite the fact that all patients reported improved self-perceived voice handicap as well as improved acoustic and aerodynamic measures (White & Carding, 2020). This disconnect may speak to the fact that functional coordination of the voice with therapy can improve despite a lack of resolution of the vocal fold lesion. As speech therapists addressing dysfunction with behavioral treatment programs, we should not define the success of intervention by the presence or absence of a vocal lesion, particularly when the patient has demonstrated improved quality of life and overall vocal function.
20. Where can I go to further augment my training in the area of voice disorders?
Ongoing additional training in the science, diagnostics, and treatment of voice disorders can be accessed through conferences, journals, and workshops that are rich in resources and support for the clinicians. You may also want to seek out a voice specialist in your area for additional opportunities to observe.
The following are links to explore:
Abbott, K. V., Li, N. Y., Branski, R. C., Rosen, C. A., Grillo, E., Steinhauer, K., & Hebda, P. A. (2012). Vocal exercise may attenuate acute vocal fold inflammation. Journal of Voice, 26(6), 814-e1.
Amin, M. R., Achlatis, S., Gherson, S., Fang, Y., Wang, B., Born, H., ... & Johnson, A. M. (2019). The role of oral steroids in the treatment of phonotraumatic vocal fold lesions in women. Otolaryngology–Head and Neck Surgery, 160(3), 512-518.
Awan, S. N., Gartner-Schmidt, J. L., Timmons, L. K., & Gillespie, A. I. (2019). Effects of a variably occluded face mask on the aerodynamic and acoustic characteristics of connected speech in patients with and without voice disorders. Journal of Voice, 33(5), 809-e1.
Behrman, A., Rutledge, J., Hembree, A., & Sheridan, S. (2008). Vocal hygiene education, voice production therapy, and the role of patient adherence: a treatment effectiveness study in women with phonotrauma. Journal of Speech, Language, and Hearing Research.
Behrman, A. (2006). Facilitating behavioral change in voice therapy: the relevance of motivational interviewing. American Journal of Speech-Language Pathology.
Behrman, A., & Sulica, L. (2003). Voice rest after microlaryngoscopy: current opinion and practice. The Laryngoscope, 113(12), 2182-2186.
Braden, M., & Verdolini Abbott, K. (2018). Advances in pediatric voice therapy. Perspectives of the ASHA Special Interest Groups, 3(3), 68-76.
Braden, M. N., van Leer, E., McConville, K., & Blakeslee, S. D. (2018). Patient, parent, and speech-language pathologists' perceptions of pediatric voice therapy through interviews. American journal of speech-language pathology, 27(4), 1385-1404.
Bradley, J. P., Hapner, E., & Johns III, M. M. (2014). What is the optimal treatment for presbyphonia?. The Laryngoscope, 124(11), 2439-2440.
Gartner-Schmidt, J., Gherson, S., Hapner, E. R., Muckala, J., Roth, D., Schneider, S., & Gillespie, A. I. (2016). The development of conversation training therapy: A concept paper. Journal of Voice, 30(5), 563-573.
Gillespie, A. I., Yabes, J., Rosen, C. A., & Gartner-Schmidt, J. L. (2019). Efficacy of Conversation Training Therapy for Patients With Benign Vocal Fold Lesions and Muscle Tension Dysphonia Compared to Historical Matched Control Patients. Journal of Speech, Language, and Hearing Research, 62(11), 4062-4079.
Guzman, M., Laukkanen, A. M., Krupa, P., Horáček, J., Švec, J. G., & Geneid, A. (2013). Vocal tract and glottal function during and after vocal exercising with resonance tube and straw. Journal of Voice, 27(4), 523-e19.
Hartley, N. A., & Thibeault, S. L. (2014). Systemic hydration: relating science to clinical practice in vocal health. Journal of Voice, 28(5), 652-e1.
Ishikawa, K., & Thibeault, S. (2010). Voice rest versus exercise: a review of the literature. Journal of Voice, 24(4), 379-387.
Johnson, A. M., & Sandage, M. J. (2019). Exercise Science and the Vocalist. Journal of Voice.
Lenell, C., Sandage, M. J., & Johnson, A. M. (2019). A tutorial of the effects of sex hormones on laryngeal senescence and neuromuscular response to exercise. Journal of Speech, Language, and Hearing Research, 62(3), 602-610.
Litts, J. K., Gartner‐Schmidt, J. L., Clary, M. S., & Gillespie, A. I. (2015). Impact of laryngologist and speech pathologist coassessment on outcomes and billing revenue. The Laryngoscope, 125(9), 2139-2142.
Maxfield, L., Titze, I., Hunter, E., & Kapsner-Smith, M. (2015). Intraoral pressures produced by thirteen semi-occluded vocal tract gestures. Logopedics Phoniatrics Vocology, 40(2), 86-92.
Meerschman, I., Claeys, S., Bettens, K., Bruneel, L., D'haeseleer, E., & Van Lierde, K. (2019). Massed versus spaced practice in vocology: Effect of a short-term intensive voice therapy versus a long-term traditional voice therapy. Journal of Speech, Language, and Hearing Research, 62(3), 611-630.
Mills, R., Hays, C., Al-Ramahi, J., & Jiang, J. J. (2017). Validation and evaluation of the effects of semi-occluded face mask straw phonation therapy methods on aerodynamic parameters in comparison to traditional methods. Journal of Voice, 31(3), 323-328.
Pasa, G., Oates, J., & Dacakis, G. (2007). The relative effectiveness of vocal hygiene training and vocal function exercises in preventing voice disorders in primary school teachers. Logopedics Phoniatrics Vocology, 32(3), 128-140.
Pestana, P. M., Vaz-Freitas, S., & Manso, M. C. (2017). Prevalence of voice disorders in singers: systematic review and meta-analysis. Journal of voice, 31(6), 722-727.
Petty, B. E. (2019). Special Considerations for Diagnosing and Treating the Classical Singer. Perspectives of the ASHA Special Interest Groups, 4(3), 483-487.
Phyland, D., & Miles, A. (2019). Occupational voice is a work in progress: active risk management, habilitation and rehabilitation. Current opinion in otolaryngology & head and neck surgery, 27(6), 439-447.
Rafii, B., Taliercio, S., Achlatis, S., Ruiz, R., Amin, M. R., & Branski, R. C. (2014). Incidence of underlying laryngeal pathology in patients initially diagnosed with laryngopharyngeal reflux. The Laryngoscope, 124(6), 1420-1424.
Rosenberg, M. D. (2014). Using semi-occluded vocal tract exercises in voice therapy: the clinician's primer. Perspectives on Voice and Voice Disorders, 24(2), 71-79.
Roy, N., & Bless, D. M. (2000). Personality traits and psychological factors in voice pathology: A foundation for future research. Journal of Speech, Language, and Hearing Research, 43(3), 737-748.
Roy, N., Merrill, R. M., Thibeault, S., Gray, S. D., & Smith, E. M. (2004). Voice disorders in teachers and the general population. Journal of Speech, Language, and Hearing Research.
Schneider, G. T., Vaezi, M. F., & Francis, D. O. (2016). Reflux and voice disorders: have we established causality?. Current otorhinolaryngology reports, 4(3), 157-167.
Sloggy, J., Stemple, J., Rowles, G., & Andreatta, R. (2019). In Support of the Exceptional Voice. Perspectives of the ASHA Special Interest Groups, 4(6), 1306-1310.
Thompson, L. L. (2001). Intensive voice treatment (LSVT) for patients with Parkinsons disease: a 2 year follow up. Journal of Neurological Neurosurgery and Psychiatry, 71, 493-498.
van Leer, E., & Connor, N. P. (2010). Patient perceptions of voice therapy adherence. Journal of Voice, 24(4), 458-469.
van Leer, E., & Connor, N. P. (2015). Predicting and influencing voice therapy adherence using social–cognitive factors and mobile video. American journal of speech-language pathology, 24(2), 164-176.
van Mersbergen, M. (2011). Voice disorders and personality: Understanding their interactions. Perspectives on Voice and Voice Disorders, 21(1), 31-38.
Van Stan, J. H., Roy, N., Awan, S., Stemple, J., & Hillman, R. E. (2015). A taxonomy of voice therapy. American Journal of Speech-Language Pathology, 24(2), 101-125.
Wenke, R. J., Stabler, P., Walton, C., Coman, L., Lawrie, M., O'Neill, J., ... & Cardell, E. (2014). Is more intensive better? Client and service provider outcomes for intensive versus standard therapy schedules for functional voice disorders. Journal of Voice, 28(5), 652-e31.
White, A. C., & Carding, P. (2020). Pre-and Postoperative Voice Therapy for Benign Vocal Fold Lesions: Factors Influencing a Complex Intervention. Journal of Voice.
Ziegler, A., Dastolfo, C., Hersan, R., Rosen, C. A., & Gartner-Schmidt, J. (2014). Perceptions of voice therapy from patients diagnosed with primary muscle tension dysphonia and benign mid-membranous vocal fold lesions. Journal of Voice, 28(6), 742-752.
Ziegler, Aaron, Katherine Verdolini Abbott, Michael Johns, Adam Klein, and Edie R. Hapner. "Preliminary data on two voice therapy interventions in the treatment of presbyphonia." The Laryngoscope 124, no. 8 (2014): 1869-1876.