Abstract
Objective:
To map the outcome assessment instruments and procedures used to determine the effect of voice therapy in adults with behavioral voice disorders.
Methods:
This scoping review was registered in the Open Science Framework (doi: 10.17605/OSF.IO/YDGA8). The guiding research question was: “What outcomes are used to assess the effects of voice therapy in adults with behavioral voice disorders?” Searches were conducted across bibliographic databases, gray literature sources, and through backward and forward citation tracking. Studies involving adults with behavioral voice disorders undergoing voice therapy were included when outcomes were assessed within the context of speech-language pathology. Data were extracted on publication characteristics, sample features, and assessment outcomes. A descriptive analysis was performed, and results were presented in figures and tables.
Results:
A total of 438 studies were included, most published in the last decade, with a marked increase in the last five years. Publications were predominantly concentrated in specialized voice journals, particularly the Journal of Voice. Samples most frequently included mixed-gender groups and both professional and non-professional voice users, with teachers representing the most common professional category. Outcome assessment was predominantly multidimensional. Laryngeal imaging, self-assessment instruments, acoustic analysis, auditory-perceptual judgment, and clinical interviews were the most frequently reported assessment components. Structural laryngeal evaluation and vocal handicap measures were the most common subcategories. The findings reflect outcomes explicitly reported in the intervention literature, and some assessment procedures may be underrepresented due to limited reporting detail in primary studies.
Conclusion:
Outcome assessment in voice therapy for behavioral voice disorders is predominantly grounded in traditional multidimensional models, with strong emphasis on laryngeal imaging and patient-reported measures. These findings underscore the central role of structural and self-perceived outcomes in clinical and research practice and highlight opportunities to expand the use of physiologically sensitive and therapy-responsive measures.
Keywords: Assessment, Evaluation, Dysphonia, Voice, Voice disorders, Voice therapy, Scoping review
INTRODUCTION
Voice disorders can be classified as entirely behavioral when related to vocal misuse or abuse, with or without the presence of laryngeal lesions, and as organic when their etiology is not related to vocal use, such as changes in vocal mechanism related to congenital anomalies, endocrine, psychiatric, neurological problems, and head and neck cancer¹. Voice disorders may affect up to 12% of the population3, and are more frequently observed in adults2–3. The prevalence varies according to the study methodology, the outcomes used, the country in which the studies were conducted, and the characteristics of the population, particularly whether the participants were voice professionals. Behavioral voice disorders can have negative consequences for quality of life and productivity4.
The primary treatment for behavioral voice disorders is voice therapy provided by speech-language pathologists (SLPs). Voice therapy commonly involves both indirect and direct approaches5. Indirect approaches include guidance and counseling on vocal use, vocal behavior, and vocal hygiene. Direct approaches aim to modify vocal behavior using techniques or voice exercises, associated or not with the use of volitional or non-volitional devices6,7.
Multidimensional voice assessments are conducted at the beginning of treatment and are critical for defining the objectives of voice therapy and developing the therapeutic plan. Due to the importance of voice assessment, multiple large organizations developed expert consensus recommendations outlining minimal and standard assessment requirements8–10. However, there is heterogeneity in these procedures. In general, these assessments frequently agree with the use of auditory-perceptual judgment, patient self-report measures, acoustic analyses, aerodynamic procedures, and laryngeal endoscopic imaging8–10. However, some procedures differ, such as patient history10 or baseline information of patients9, clinical instruments associated with voice comorbidities10, laryngeal electromyography9, swallowing function assessment9, and assessment of laryngopharyngeal reflux9, which are indicated only in specific recommendations. Except for laryngeal examinations, the assessment procedures are commonly performed by the SLPs.
There are currently several assessment procedures, including the above and additional procedures, as well as many instruments and measures that can be used in each form of assessment. There is variability in consensus in the literature on which procedures and measures are most relevant for each type of voice disorder8–10. However, in the clinical or research environment, each type of voice disorder has procedures and measures with varying weights in therapeutic decision-making. For example, soft phonation index (SPI) can detect abnormalities in vocal fold approximation in individuals with vocal nodules11; the noise-to-harmonic ratio (NHR) can distinguish laryngospasm12; the standard deviation of fundamental frequency (f₀SD) is effective in differentiating subgroups of neurological voice disorders13; relative fundamental frequency (RFF) is recognized as a marker of vocal hyperfunction14; cepstral peak prominence (CPP) and difference between the amplitude of the first and second harmonics (H1–H2) are used to distinguish nonphonotraumatic vocal hyperfunction and vocally healthy individuals15; and, H1-H2 and sound pressure level are considered markers of phonotraumatic vocal hyperfunction16.
Categorizing and systematizing the most frequently used outcomes can help clarify which procedures are most valued among clinicians and researchers. After mapping the outcomes, clinicians and researchers can describe how each outcome supports therapeutic planning for all adults with different types of voice disorders or with specific disorders. In this way, these data can help identify the mechanisms of action, targets, and aims of voice therapy17. Identifying the degree to which outcomes directly or indirectly relate to therapy will help optimize and tailor treatment to improve results, shorten treatment time, and enhance the durability of those results, among other benefits.
Thus, this scoping review aims to map the outcome assessment instruments and procedures used to determine the effect of voice therapy in adults with behavioral voice disorders.
METHOD
This scoping review followed the methodological recommendations of the Joanna Briggs Institute (JBI)18. The article was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR)19. The review protocol was registered in the Open Science Framework (doi: 10.17605/OSF.IO/YDGA8).
A preliminary search revealed no ongoing reviews with similar objectives and identified primary studies relevant to this scoping review. The acronym PCC (Population, Concept, and Context) was used to define the research question. This review considered adults with behavioral voice disorders as the population, outcomes used to evaluate voice therapy as the concept, and outpatient speech-language pathology as the context. The research question that supported the development of this scoping review was: “What outcomes are used to assess the effect of voice therapy in adults with behavioral voice disorders?” Eligibility criteria were developed for the selected studies. The eligibility criteria were:
Participants
Studies involving only individuals over 65 years of age (to exclude presbyphonia), individuals under 18 years of age (to avoid changes related to maturation and puberty), individuals without vocal complaints or a diagnosis of a voice disorder, or those with complaints solely induced by vocal fatigue or overload during the study were excluded.
Concept
The studies included those that performed voice assessment before and/or after the intervention and used voice therapy. Excluded studies were those that did not perform any voice assessment, those that used voice therapy but evaluated non-voice outcomes, and those that did not undergo voice therapy. This rationale ensures that only studies with a clear focus on assessing voice outcomes related to voice therapy are included, in alignment with the review’s objective.
Context
Included studies were those in which speech-language pathologists (SLPs) delivered voice therapy. Excluded studies were those in which non-SLPs delivered voice therapy. This criterion ensures that the intervention under analysis reflects the scope of practice and clinical competencies specific to SLPs.
Types of Sources
Quasi-experimental studies and experimental studies were included because the research question focuses on assessing the effects of specific interventions. Observational studies (such as cross-sectional, case-control, or cohort studies) were excluded because they do not involve active manipulation of variables and, therefore, are not appropriate for evaluating the effectiveness of interventions. Additionally, studies that did not report primary patient data, such as literature reviews, conference proceedings, books, book chapters, reports, editorials, and letters to the editor, were excluded. There was no publication year or language filter.
Search strategies were developed to locate published and unpublished studies. The indexed terms (Medical Subject Headings – MeSH and Entree Terms) and the free terms were associated with the previously described PCC categories. An initial MEDLINE/PubMed search was performed to identify additional free terms in the titles, keywords, or index terms used to refine the search strategy. A final search strategy was established for MEDLINE/PubMed. This strategy was adapted to the other sources of evidence (Appendix 1).
Searches were conducted across bibliographic databases and other methods, including gray literature sources and citation tracking. Electronic searches were conducted in MEDLINE/PubMed, Latin American and Caribbean Literature on Health Sciences (LILACS), Scopus (Elsevier), Web of Science, EMBASE (Elsevier), and the Cochrane Library. Gray literature searches were conducted through ProQuest Dissertations and Theses, MedRxiv, and Google Scholar (top 100 results)20,21. Additional records were identified through backward and forward citation tracking of included studies.
After completion of the searches, all records were imported into Rayyan. The selection of articles was carried out in three stages: (a) removal of duplicates; (b) screening of titles and abstracts against the inclusion criteria; and (c) full-text assessment applying the exclusion criteria. Reasons for exclusion at the full-text stage were recorded and are reported. The search and selection process is presented in a flow diagram in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR)22.
Two independent reviewers selected the items, and disagreements at each stage of the process were resolved by consensus. Before reviewing all articles, the two reviewers completed a calibration session with the first 25 articles found in PUBMED/MEDLINE. Calibration was repeated with additional articles until a Cohen’s kappa coefficient of 0.8 or higher was achieved, indicating substantial agreement.
Two independent reviewers extracted the data. The data were combined, and a third reviewer resolved any disagreements. The authors developed a structured data extraction form, pilot-tested it prior to full data extraction, and made it fully available in the published review protocol. Data were extracted on the characteristics of the publications, the sample, and the outcomes used for assessment. If any information required for the data extraction process was not available in the article, the corresponding author was contacted via email. Up to three attempts were made, with a maximum interval of seven days between each.
A descriptive analysis was conducted for all variables. Quantitative variables were summarized using measures of central tendency and dispersion, while qualitative variables were summarized using absolute and relative frequencies. Data analysis was performed using IBM SPSS Statistics (IBM SPSS Statistics version 29.0.2.0) and R software (RStudio version 2026.01.0, Build 392; Posit Software, PBC). The synthesis of the results was presented in a narrative format, including figures and tables.
RESULTS
A total of 6,545 records were identified through database searching, including LILACS (n = 175), MEDLINE/PubMed (n = 1,747), Cochrane (n = 333), Embase (n = 1,268), Scopus (n = 2,057), and Web of Science (n = 965). No records were identified from the trial registers. After removal of 3,844 duplicate records, 2,701 records remained and were screened by title and abstract, resulting in the exclusion of 2,398 records. Subsequently, 303 reports were sought for full-text retrieval; one report could not be retrieved. Thus, 302 reports were assessed for eligibility, and 16 reports were excluded due to inclusion of vocally healthy populations (n = 14) or inappropriate study design (n = 2).
In parallel, 10,919 records were identified through other methods. Of these, 10,775 records were identified through citation searching, comprising backward citation searching (reference list screening; n = 7,301) and forward citation searching (citation tracking; n = 3,474). In addition, 144 records were identified through grey literature sources, including Google Scholar (n = 100), ProQuest Dissertations and Theses (n = 2), and medRxiv (n = 42). From these sources, 217 reports were sought, of which 28 could not be retrieved. Consequently, 189 reports were assessed for eligibility. Of these, 37 reports were excluded due to inclusion of vocally healthy populations (n = 26), inappropriate study design (n = 7), or absence of a voice therapy intervention (n = 4).
In total, 438 studies met the inclusion criteria and were included in the review (Figure 1).
Figure 1.
PRISMA 2020 flow diagram of the study selection process
The flow diagram was generated using the PRISMA 2020 Shiny App to produce a PRISMA 2020–compliant flow diagram. Source: Haddaway NR, Page MJ, Pritchard CC, McGuinness LA42
Figure 2 shows that the temporal distribution of studies indicates a clear concentration of publications in recent years. The most productive years were 2023 (n = 38; 8.68%), 2017 (n = 36; 8.22%), and 2024 (n = 34; 7.76%), together accounting for approximately 25% of all included studies. Overall, the data demonstrate a marked increase in scientific output over the last decade, with a particularly pronounced rise in the most recent five-year period.
Figure 2.
Scientific production of voice therapy studies in behavioral voice disorders over time
Regarding the dissemination venues, publications were predominantly concentrated in specialized journals in the field of voice and communication disorders (Table 1). The Journal of Voice was the most frequent outlet, publishing 170 studies (38.81%), followed by Folia Phoniatrica et Logopaedica (n = 19; 4.34%) and CoDAS (n = 17; 3.88%). These three journals together accounted for nearly 47% of all publications, indicating a strong centralization of scientific output in journals with a specific focus on voice, speech-language pathology, and related interdisciplinary areas.
Table 1.
Distribution of voice therapy studies in behavioral voice disorders according to the journal of publication
| Variable and categories | n | % |
|---|---|---|
|
| ||
| Journal | ||
| Journal of Voice | 170 | 38.81 |
| Folia Phoniatrica et Logopaedica | 19 | 4.34 |
| CoDAS | 17 | 3.88 |
| Journal of speech, language, and hearing research | 16 | 3.65 |
| Revista CEFAC | 14 | 3.20 |
| Audiology - Communication Research | 11 | 2.51 |
| The Laryngoscope | 11 | 2.51 |
| American journal of speech-language pathology | 9 | 2.05 |
| Communication Sciences and Disorders | 7 | 1.60 |
| Logopedics, phoniatrics, vocology | 7 | 1.60 |
| Distúrbios da Comunicação | 6 | 1.37 |
| European archives of oto-rhino-laryngology | 6 | 1.37 |
| Journal of Communication Disorders | 6 | 1.37 |
| Revista de Logopedia, Foniatria y Audiologia | 6 | 1.37 |
| The Journal of Laryngology & Otology | 6 | 1.37 |
| Japan Journal of Logopedics and Phoniatrics | 5 | 1.14 |
| The Japan Journal of Logopedics and Phoniatrics | 5 | 1.14 |
| International Journal of Language & Communication Disorders | 4 | 0.91 |
| International Journal of Phonosurgery & Laryngology | 4 | 0.91 |
| Medycyna Pracy | 4 | 0.91 |
| Acta Otorhinolaryngologica Italica | 3 | 0.68 |
| American journal of otolaryngology | 3 | 0.68 |
| Auris, nasus, larynx | 3 | 0.68 |
| Journal of The Korean Society of Laryngology, Phoniatrics and Logopedics | 3 | 0.68 |
| Kulak burun bogaz ihtisas dergisi | 3 | 0.68 |
| Phonetics and Speech Sciences | 3 | 0.68 |
| Brazilian Journal of Otorhinolaryngology | 2 | 0.46 |
| Clinical otolaryngology and allied sciences | 2 | 0.46 |
| Dissertação de Mestrado | 2 | 0.46 |
| Indian Journal of Otolaryngology and Head & Neck Surgery | 2 | 0.46 |
| International journal of occupational medicine and environmental health | 2 | 0.46 |
| Iranian journal of otorhinolaryngology | 2 | 0.46 |
| Jornal da Sociedade Brasileira de Fonoaudiologia | 2 | 0.46 |
| Journal of Clinical Medicine | 2 | 0.46 |
| Journal of Laryngology and Voice | 2 | 0.46 |
| Otolaringologia polska | 2 | 0.46 |
| Pró-fono | 2 | 0.46 |
| Revista da Sociedade Brasileira de Fonoaudiologia | 2 | 0.46 |
| The Annals of otology, rhinology, and laryngology | 2 | 0.46 |
| The Journal of speech and hearing disorders | 2 | 0.46 |
| Iranian Registry of Clinical Trials (IRCT20181125041752N1) | 1 | 0.23 |
| Acta de Otorrinolaringología & Cirugía de cabeza y cuello | 1 | 0.23 |
| Advances in therapy | 1 | 0.23 |
| Ain Shams Medical Journal | 1 | 0.23 |
| Applied Sciences | 1 | 0.23 |
| Archives of otolaryngology--head & neck surgery | 1 | 0.23 |
| Asia Pacific Journal of Speech, Language and Hearing | 1 | 0.23 |
| Auditory and Vestibular Research | 1 | 0.23 |
| Bimonthly Audiology - Tehran University of Medical Sciences | 1 | 0.23 |
| Biofeedback and self-regulation | 1 | 0.23 |
| Clinical Archives of Communication Disorders | 1 | 0.23 |
| Clinical otolaryngology | 1 | 0.23 |
| Clinical Research | 1 | 0.23 |
| Ear, nose, & throat journal | 1 | 0.23 |
| Egyptian Journal of Otolaryngology | 1 | 0.23 |
| European journal of disorders of communication | 1 | 0.23 |
| Evidence-based complementary and alternative medicine | 1 | 0.23 |
| Experimental and Therapeutic Medicine | 1 | 0.23 |
| Healthcare | 1 | 0.23 |
| Indian journal of otolaryngology and head and neck surgery | 1 | 0.23 |
| Indian Journal of Otology | 1 | 0.23 |
| International Congress Series | 1 | 0.23 |
| International journal of pediatric otorhinolaryngology | 1 | 0.23 |
| International journal of rehabilitation research. Internationale Zeitschrift fur Rehabilitationsforschung. Revue internationale de recherches de readaptation | 1 | 0.23 |
| International Journal of Speech-Language Pathology | 1 | 0.23 |
| JASA Express Lett | 1 | 0.23 |
| Journal of Academic Research in Medicine | 1 | 0.23 |
| Journal of Associated Medical Sciences | 1 | 0.23 |
| Journal of Ear Nose Throat and Head Neck Surgery | 1 | 0.23 |
| Journal of Otolaryngology - Head & Neck Surgery | 1 | 0.23 |
| Journal of Otolaryngology-ENT Research | 1 | 0.23 |
| Journal of the Formosan Medical Association = Taiwan yi zhi | 1 | 0.23 |
| Kathmandu University Medical Journal (KUMJ) | 1 | 0.23 |
| Korean Journal of Otorhinolaryngology-Head and Neck Surgery | 1 | 0.23 |
| Koutou (The Larynx Japan) | 1 | 0.23 |
| Laryngo-Rhino-Otologie | 1 | 0.23 |
| Nihon Jibiinkoka Gakkai kaiho | 1 | 0.23 |
| Noise & health | 1 | 0.23 |
| Otolaryngology--head and neck surgery | 1 | 0.23 |
| Pilot and feasibility studies | 1 | 0.23 |
| Physical Therapy | 1 | 0.23 |
| Polski Przegląd Otorynolaryngologiczny | 1 | 0.23 |
| Practica Oto-Rhino-Laryngologica | 1 | 0.23 |
| Praxis | 1 | 0.23 |
| Research Square | 1 | 0.23 |
| Revista Chilena de Fonoaudiología | 1 | 0.23 |
| Revista de Investigación en Logopedia | 1 | 0.23 |
| Revista de la Federación Argentina de Sociedades de Otorrinolaringología | 1 | 0.23 |
| Saudi Medical Journal | 1 | 0.23 |
| Seminars in speech and language | 1 | 0.23 |
| Shiraz e medical journal | 1 | 0.23 |
| Srpski arhiv za celokupno lekarstvo | 1 | 0.23 |
| Tese de Doutorado | 1 | 0.23 |
| The Egyptian Journal of Otolaryngology | 1 | 0.23 |
| The Journal of the Medical Association of Thailand | 1 | 0.23 |
| The South African journal of communication disorders | 1 | 0.23 |
| Turkish archives of otorhinolaryngology | 1 | 0.23 |
| Vojnosanitetski pregled | 1 | 0.23 |
| Yearbook of Otolaryngology-Head and Neck Surgery | 1 | 0.23 |
| Total | 438 | 100.00 |
Regarding the geographical distribution of studies, when studies were classified by national or multinational origin, Brazil had the highest number of publications (n = 90), followed by the United States (n = 79) and Japan (n = 23). When multinational studies were subsequently counted individually for each participating country (Figure 3), the distribution changed. Under this approach, the United States showed the highest number of records (n = 96), followed by Brazil (n = 93) and Japan (n = 26). Iran (n = 25), South Korea (n = 22), Chile (n = 20), Turkey (n = 17), and the United Kingdom (n = 17) were also among the countries with the highest frequencies. China (n = 16), Belgium (n = 15), India (n = 13), Poland (n = 12), the Netherlands (n = 11), and Spain (n = 11) followed. Italy (n = 10), Finland (n = 8), Sweden (n = 8), Taiwan (n = 8), Australia (n = 7), and Germany (n = 6) completed the distribution.
Figure 3.
Distribution of voice therapy studies in behavioral voice disorders according to geographical origin
The characteristics of the participants included in the analyzed studies are summarized below. Regarding gender, most studies reported samples including both genders, accounting for 60.27% of the participants (n = 264). Female participants represented 27.85% (n = 122), while male participants accounted for 4.34% (n = 19). Gender information was not reported for 7.53% of the participants (n = 33) (Figure 4).
Figure 4.
Distribution of voice therapy studies in behavioral voice disorders according to professional voice user status and participant gender
Concerning voice use, the majority of participants were classified as non–professional voice users (59.82%; n = 262), whereas 38.58% (n = 169) were identified as professional voice users. Information regarding professional voice use was not reported for 1.60% of the sample (n = 7) (Figure 4). Among participants identified as professional voice users (n = 169), teachers constituted the largest group, representing 62.72% (n = 106). Musicians and singers accounted for 26.63% (n = 45). Other professional voice categories were less frequently represented and included call center operators (7.10%), sales professionals (6.51%), health professionals (6.51%), announcers or hosts (5.33%), lecturers or counselors (4.73%), students training for voice-related professions (4.14%), business professionals (2.96%), artists (2.37%), secretaries (2.37%), clergy members (2.37%), journalists or reporters (1.78%), lawyers or court interpreters (1.18%), and other occupations with individual frequencies below 1% (Figure 5)
Figure 5.
Distribution of voice therapy studies in behavioral voice disorders according to professional voice user categories
Regarding the assessment procedures adopted in the included studies, most investigations reported the use of multiple assessment components. Vocal complaint was the most frequently reported component, being described in 362 studies (82.65%), followed by interview or anamnesis in 331 studies (75.57%). Laryngeal imaging was reported in 328 studies (74.89%), and self-assessment instruments were used in 319 studies (72.83%). Acoustic analysis was performed in 307 studies (70.09%), while auditory-perceptual judgment was reported in 271 studies (61.87%). Aerodynamic assessment was less frequently employed, being reported in 174 studies (39.73%). The distribution of assessment components across studies is illustrated in Figure 6.
Figure 6.
Distribution of voice therapy studies in behavioral voice disorders according to the type of vocal assessment performed
Figure 7 shows that, among studies reporting laryngeal imaging (n = 328), the most frequently reported subtype was structural assessment of the larynx, appearing in 321 studies (97.9%). Vibratory assessment during phonation was described in 227 studies (69.2%). High-speed imaging techniques were rarely reported, appearing in 8 studies (2.4%).
Figure 7.
Distribution of voice therapy studies in behavioral voice disorders according to assessment subcategories
Among studies that reported self-assessment instruments (n = 319), measures of vocal handicap or disadvantage were the most frequently used subtype, reported in 182 studies (57.1%). Global self-ratings of voice were reported in 88 studies (27.6%), and instruments focused on vocal symptoms were reported in 57 studies (17.9%).
Among studies that reported acoustic analysis (n = 307), frequency-related measures were the most frequently described subtype, appearing in 206 studies (67.1%). Measures of frequency perturbation, such as jitter-related indices, were reported in 202 studies (65.8%). Amplitude perturbation measures, including shimmer-related indices, were described in 184 studies (59.9%).
Among studies that reported auditory-perceptual judgment (n = 271), the most frequently used subtype was the GRBAS or GRBASI scale, reported in 142 studies (52.4%). The CAPE-V was the second most frequently reported tool, appearing in 47 studies (17.3%). Scales focused on overall vocal deviation were reported in 32 studies (11.8%).
Among studies that reported aerodynamic assessment (n = 174), measures related to vocal efficiency were the most frequently reported subtype, appearing in 140 studies (80.5%). Airflow-related measures were described in 62 studies (35.6%), while pressure-related measures were reported in 56 studies (32.2%).
DISCUSSION
The categorization and systematization of the outcomes most frequently used to assess the effects of voice therapy on voice behavioral disorders clarify which procedures are most used by researchers and clinicians in the field of voice. In this context, the identification of the degree to which the outcomes are directly or indirectly related to voice therapy provides insights into the mechanisms of action, therapeutic targets, and objectives of the intervention17. In addition, this analysis can support the optimization and personalization of treatment and impact its effectiveness, whether by reducing time, achieving better results, or improving the durability of the results. Based on this, the present scoping review proposes to map and present the main outcomes used to evaluate the effects of voice therapy in adults with behavioral voice disorders.
Regarding the characteristics of the publications, there has been significant growth in scientific production on voice therapy for behavioral voice disorder over the last 13 years, with an even more pronounced increase in the last 5 years. This pattern may reflect the expansion of interest in the systematic measurement of therapeutic processes and the consolidation of voice therapy as a field of scientific research, at this moment of maturity that evidence-based practices in the area of voice are experiencing. The diversity of cases in the vocal clinic contributes to the development of further research, with more robust designs, to refine knowledge about methods, techniques, and exercises across different application formats and dosages24,25.
The largest concentration of publications is in the Journal of Voice. This result is expected, since the subject of voice therapy is aligned with the scope of the journal, which today concentrates the greatest diversity of high-level scientific publications in the area26.
The geographical distribution of studies revealed the prominent roles of both Brazil and the United States in the scientific production on voice therapy. While Brazil had the highest number of studies when classified by national or multinational origin, the United States emerged as the most frequent contributor when multinational studies were counted individually for each participating country.
The consistent prominence of Brazil across both analytical approaches highlights the strengthening of Brazilian scientific production in this field. Brazil currently hosts a large number of well-established research groups dedicated to voice therapy, distributed across major university centers, with Dr. Mara Behlau standing out as a senior researcher with recognized expertise in the area. Historically, voice therapy has represented a particularly strong field within Brazilian Speech-Language Pathology. Unlike in many other countries, Brazilian professionals pursuing a career in Speech-Language Pathology are required to complete a mandatory undergraduate degree, after which they are fully qualified and authorized to provide clinical care across multiple domains, including voice therapy. This educational and professional structure contributes to the sustained demand for intervention studies capable of supporting clinical training and practice, thereby fostering the development of robust scientific evidence focused on therapeutic effectiveness27. In contrast, the leading position of the United States under the individual country-counting approach reflects its strong participation in multinational research networks and collaborative studies. This pattern is consistent with the organization of research in the United States, which is characterized by large academic and clinical centers and a strong tradition of international collaboration in voice and laryngology research characterize.
Together, these findings indicate complementary profiles of scientific production, with Brazil standing out for the volume of nationally conducted studies closely aligned with professional training and clinical practice, and the United States for extensive participation in multinational and collaborative research initiatives. This pattern underscores the global and interconnected nature of research in voice therapy and highlights the relevance of both national research capacity and international collaboration for advancing evidence-based practice in the field.
Regarding the characteristics of the sample, the studies most frequently include both genders and a mixed sample, composed of voice professionals and non-professionals. These data show a broad understanding of behavioral voice disorder as a condition influenced by different vocal-use contexts and sex differences, reflected in the need for therapeutic specificity28. In addition, both factors are predictive of participation in therapy, with women and voice professionals showing a greater willingness to choose voice therapy as the primary treatment for voice disorders 28. This population diversity strengthens the clinical applicability of the findings.
The predominance of teachers among professional voice users reported in the included studies reflects the profile of the samples studied in the analyzed literature, rather than the prevalence of behavioral voice disorders in specific professional categories. Owing to the frequent reporting of behavioral voice disorder in this population, teachers have become a major focus of research on this topic29,30. The representation of musicians, singers, and other occupations with vocal demands indicates that the studies address a variety of voice-use contexts, supporting the understanding of behavioral voice disorder as a condition associated with patterns of voice use and vocal behavior. Accordingly, these data should be interpreted as indicative of the scope of the published investigations, contributing to the discussion of the clinical applicability of the findings without allowing epidemiological inferences regarding risk or distribution of behavioral voice disorder across professions.
Regarding outcomes, vocal complaints are consistently reported in studies, often in the characterization or eligibility criteria. This data evidences, even in the scientific environment, the importance of the patient’s demand and reflects its primary clinical function as a gateway to the therapeutic process, allowing the identification of individuals who require intervention and the organization of the subsequent assessment sequence31. This data is important for eligibility, since a sample composed of people with and without complaints can lead to differences in adherence models and generate a confounding factor in the results. In addition, specifically in behavioral voice disorder, vocal complaints play a structuring role in clinical reasoning and therapeutic planning, as they guide the identification of priority functional demands, contextualize vocal use, and direct the definition of therapeutic targets. Thus, the complaint is not configured as a measure of severity or outcome, but as an organizing element of the therapeutic process, from which the assessment data gain clinical interpretation. Its integration into multidimensional voice assessment underpins therapeutic decisions aligned with high-level clinical practice.
Auditory-perceptual judgment (APJ) is widely used in the studies analyzed, with the GRBAS protocol predominating. This finding reaffirms the central role of the APJ in voice therapy and the tradition of this instrument in the assessment of voice quality32. Despite its wide acceptance, GRBAS also has known limitations, such as limited sensitivity to subtle changes in the same degree of alteration, especially in the context of therapeutic follow-up of participants with less deviated voices. As a result, APJ has been increasingly used in conjunction with other measures capable of detecting more subtle changes in voice quality resulting from the intervention32.
In this sense, acoustic analysis, consistently present, is identified as the most frequently used outcome in the studies analyzed in this scoping review. Acoustic analysis today is low cost, easy to perform and interpret, and brings accurate results, of high sensitivity and specificity, to physiologically understand vocal production, classify the presence and severity of voice disorders, and facilitate the clinical interpretation of the case32–34. In addition, the acoustic parameters have a high correlation with the APJ of the voice, likely because human hearing relies on acoustics35,36. The most frequent parameters were still the traditional ones, with higher counts of frequency and amplitude disturbance measurements. These parameters reflect the search for objectivity and the historical consolidation of these measures in the area of voice. However, it is known that the use of cepstral and spectral measurements and multiparametric indices is increasingly common, especially in cases of voice disorders, as in the present study. These parameters, which are more robust and stable in deviated voices, have enabled greater ability to capture relevant therapeutic changes. However, the need to update the assessment models to align with available technological advances is emphasized.
Aerodynamic assessment is infrequent in studies, although it does extract change-sensitive measures after voice therapy and is useful for understanding phonatory effort and glottic efficiency in behavioral voice disorder37,38. The barriers to the routine implementation of aerodynamic measurements are numerous and may include equipment costs and availability, collection time, standardization, data interpretation, and insufficient training, although guidelines recommend its use in the minimum procedures that make up the multidimensional voice assessment39. Among those who use aerodynamic assessment, measures related to vocal efficiency predominate, followed by airflow measurements and, to a lesser extent, subglottic pressure. The limited use of more comprehensive aerodynamic measures may reflect clinical assumptions that acoustic measures sufficiently capture aerodynamic–acoustic interactions, as well as practical considerations. In this context, maximum phonation time emerges as the most frequently used indicator of vocal efficiency, likely due to its ease of administration, rapid acquisition, and low cost.
Most studies include vocal self-assessment instruments, especially those focused on perceived vocal handicap, such as the Vocal Handicap Index, its shortened versions, or adaptations to different contexts, and global voice self-assessment, which is commonly measured by instruments developed by the researchers themselves. This finding evidences recognition of the psychosocial impact of voice disorder and appreciation of the patient’s perspective in the therapeutic process40. Self-assessment is the most important outcome for the decision on the moment of therapeutic discharge, because if the patient no longer has demand, even if there are still issues to be improved, he will not complete the treatment41. Thus, continuous monitoring through self-assessment is essential during the therapeutic process, as the patient’s perception of benefit directly influences engagement, adherence, and continuity of care, and should therefore guide clinical decision-making.
Imaging tests are mainly used for structural assessment of the vocal folds, followed by their use in the vibration analysis of the vocal folds during phonation. These tests play a fundamental role in excluding organic alterations and in the initial characterization of voice disorders. However, its application as a therapeutic monitoring tool is limited, since in most countries the SLP cannot perform the test, reinforcing the separation between medical assessment for diagnostic confirmation and speech-language pathology follow-up.
Taken together, the findings suggest that, despite the expansion of scientific production, voice assessment practices have undergone limited structural change over the past two decades. Although certain technological advances have been incorporated, such as improvements in laryngeal imaging and the inclusion of cepstral measures, the overall evaluative framework remains largely centered on traditional components. The limited adoption of more physiologically specific or potentially more sensitive measures may not necessarily reflect a lack of evidence, but rather challenges in translating emerging research findings into routine clinical practice. In this context, future efforts grounded in implementation science may be necessary to facilitate the integration of newer outcome measures into everyday voice assessment.
In this context, the vocal complaint maintains a central role in therapeutic planning, serving as a starting point for organizing the multidimensional assessment and defining the intervention targets. Moving towards more integrated evaluative models, aligned with the physiological and functional objectives of voice therapy and sensitive to therapeutic changes, represents a challenge and an opportunity for the future development of the area. It is necessary to mature the use of a contemporary therapeutic organization, such as the RTSS-Voice model, which can help better align the characteristics of patients with the rationale for the best choice of measures to monitor the main targets of the intervention.
CONCLUSION
Voice therapy research in adults with behavioral voice disorders has shown substantial growth over recent decades, particularly in the last ten years, reflecting the increasing interest in evidence-based clinical practice. The findings indicate that assessment of therapeutic effects is predominantly grounded in traditional multidimensional models, with frequent use of vocal complaint, laryngeal imaging, self-assessment instruments, acoustic analysis, and auditory-perceptual judgment.
Laryngeal imaging and self-assessment measures emerged as the most frequently reported outcomes, highlighting their central roles in diagnostic characterization and in capturing the patient’s perspective, respectively. However, their high frequency of use does not necessarily correspond to greater sensitivity to therapeutic change, particularly when considered as primary outcomes for monitoring intervention effects. The prominence of these measures appears to reflect established clinical routines and historical assessment models rather than outcome selection driven by responsiveness to therapy.
The comparatively lower use of aerodynamic measures and advanced acoustic indices suggests a persistent misalignment between the physiological targets of voice therapy and the outcomes selected to evaluate its effects. This gap may limit the ability to precisely capture therapeutic mechanisms and subtle functional changes associated with intervention.
Taken together, these findings emphasize the need for greater alignment between therapeutic objectives, physiological mechanisms, and outcome selection in voice therapy research and clinical practice. The adoption of integrative, theory-driven frameworks to guide assessment, such as contemporary rehabilitation specification models, may contribute to more coherent, sensitive, and clinically meaningful evaluation strategies, ultimately enhancing the interpretability and impact of voice therapy outcomes.
This scoping review has some limitations that should be acknowledged. First, the analysis relied on the outcomes explicitly reported in the included studies; therefore, assessment procedures that were applied but insufficiently described may not have been captured. Second, although outcome categories were defined a priori, the classification process was constrained by variability and limited detail in outcome reporting across primary studies, which may have influenced the grouping of specific measures. Finally, emerging outcome measures may be underrepresented due to their still limited adoption in intervention studies.
Funding:
This study was supported by the Brazilian National Council for Scientific and Technological Development (CNPq) through research fellowships (grant numbers 404754/2024–4 and 102159/2024–6). Dr. Van Stan’s work was supported by the National Institute on Deafness and Other Communication Disorders via grant R01 DC020247. The article’s contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.
Appendices
Appendix A: Search strategy
1. PubMed/Medline
(“Voice Disorders”[tiab] OR “Voice Disorders”[Mesh] OR “Dysphonia”[tiab] OR “Dysphonia”[Mesh] OR “voice disorder”[tiab] OR “voice disturbance”[tiab] OR “voice disturbances”[tiab] OR “phonation disorder”[tiab] OR “phonation disorders”[tiab] OR “phonatory disorder”[tiab] OR “phonatory disorders”[tiab] OR “voice problems”[tiab] OR “vocal problems”[tiab] OR “vocal complaints”[tiab] OR “voice complaints”[tiab] OR “Functional Dysphonia”[tiab] OR “Organofunctional Dysphonia”[tiab] OR “Behavioral Dysphonia”[tiab] OR “Muscle Tension Dysphonia”[tiab] OR “Hyperfunctional Dysphonia”[tiab] OR “Hyperkinetic Dysphonia”[tiab] OR “Hyperfunctional Dysphonia”[tiab]) AND (“Voice Training”[Mesh] OR “Voice Training”[tiab] OR “Vocal Training”[tiab] OR “Voice Trainings”[tiab] OR “Voice Therapy”[tiab] OR “Vocal Therapy”[tiab] OR “Voice Intervention”[tiab] OR “Vocal Intervention”[tiab] OR “Voice Rehabilitation”[tiab] OR “Vocal Rehabilitation”[tiab] OR “Phonotherapy”[tiab] OR “Voice exercise”[tiab] OR “Voice exercises”[tiab])
2. LILACS
(tw:(“Voice Disorders” OR “Dysphonia” OR “voice disorder” OR “voice disturbance” OR “voice disturbances” OR “phonation disorder” OR “phonation disorders” OR “phonatory disorder” OR “phonatory disorders” OR “voice problems” OR “vocal problems” OR “vocal complaints” OR “voice complaints” OR “Functional Dysphonia” OR “Organofunctional Dysphonia” OR “Behavioral Dysphonia” OR “Muscle Tension Dysphonia” OR “Hyperfunctional Dysphonia” OR “Hyperkinetic Dysphonia” OR “Hyperfunctional Dysphonia”)) AND (tw:(“Voice Training” OR “Vocal Training” OR “Voice Trainings” OR “Voice Therapy” OR “Vocal Therapy” OR “Voice Intervention” OR “Vocal Intervention” OR “Voice Rehabilitation” OR “Vocal Rehabilitation” OR “Phonotherapy” OR “Voice exercise” OR “Voice exercises”)) AND (mh:(“Voice Disorders” OR “Dysphonia” OR “Voice Training”))
3. Web of Science
TS=(“Voice Disorders” OR “Dysphonia” OR “voice disorder” OR “voice disturbance” OR “voice disturbances” OR “phonation disorder” OR “phonation disorders” OR “phonatory disorder” OR “phonatory disorders” OR “voice problems” OR “vocal problems” OR “vocal complaints” OR “voice complaints” OR “Functional Dysphonia” OR “Organofunctional Dysphonia” OR “Behavioral Dysphonia” OR “Muscle Tension Dysphonia” OR “Hyperfunctional Dysphonia” OR “Hyperkinetic Dysphonia” OR “Hyperfunctional Dysphonia”) AND TS=(“Voice Training” OR “Vocal Training” OR “Voice Trainings” OR “Voice Therapy” OR “Vocal Therapy” OR “Voice Intervention” OR “Vocal Intervention” OR “Voice Rehabilitation” OR “Vocal Rehabilitation” OR “Phonotherapy” OR “Voice exercise” OR “Voice exercises”)
4. Scopus
TITLE-ABS-KEY({Voice Disorders} OR {Dysphonia} OR {voice disorder} OR {voice disturbance} OR {voice disturbances} OR {phonation disorder} OR {phonation disorders} OR {phonatory disorder} OR {phonatory disorders} OR {voice problems} OR {vocal problems} OR {vocal complaints} OR {voice complaints} OR {Functional Dysphonia} OR {Organofunctional Dysphonia} OR {Behavioral Dysphonia} OR {Muscle Tension Dysphonia} OR {Hyperfunctional Dysphonia} OR {Hyperkinetic Dysphonia} OR {Hyperfunctional Dysphonia}) OR INDEXTERMS({Voice Disorders} OR {Dysphonia}) AND TITLE-ABS-KEY({Voice Training} OR {Vocal Training} OR {Voice Trainings} OR {Voice Therapy} OR {Vocal Therapy} OR {Voice Intervention} OR {Vocal Intervention} OR {Voice Rehabilitation} OR {Vocal Rehabilitation} OR {Phonotherapy} OR {Voice exercise} OR {Voice exercises}) OR INDEXTERMS({Voice Training})
5. EMBASE
(‘Voice Disorder’/exp OR ‘Dysphonia’/exp OR ‘voice disorder’:ti,ab,kw OR ‘voice disturbance’:ti,ab,kw OR ‘voice disturbances’:ti,ab,kw OR ‘phonation disorder’:ti,ab,kw OR ‘phonation disorders’:ti,ab,kw OR ‘phonatory disorder’:ti,ab,kw OR ‘phonatory disorders’:ti,ab,kw OR ‘voice problems’:ti,ab,kw OR ‘vocal problems’:ti,ab,kw OR ‘vocal complaints’:ti,ab,kw OR ‘voice complaints’:ti,ab,kw OR ‘Functional Dysphonia’:ti,ab,kw OR ‘Organofunctional Dysphonia’:ti,ab,kw OR ‘Behavioral Dysphonia’:ti,ab,kw OR ‘Muscle Tension Dysphonia’:ti,ab,kw OR ‘Hyperfunctional Dysphonia’:ti,ab,kw OR ‘Hyperkinetic Dysphonia’:ti,ab,kw) AND (‘Voice Training’/exp OR ‘Voice Training’:ti,ab,kw OR ‘Vocal Training’:ti,ab,kw OR ‘Voice Trainings’:ti,ab,kw OR ‘Voice Therapy’:ti,ab,kw OR ‘Vocal Therapy’:ti,ab,kw OR ‘Voice Intervention’:ti,ab,kw OR ‘Vocal Intervention’:ti,ab,kw OR ‘Voice Rehabilitation’:ti,ab,kw OR ‘Vocal Rehabilitation’:ti,ab,kw OR ‘Phonotherapy’:ti,ab,kw OR ‘Voice exercise’:ti,ab,kw OR ‘Voice exercises’:ti,ab,kw)
6. Cochrane Central Register of Controlled Trials
(MeSH descriptor: [Voice Disorders] OR MeSH descriptor: [Dysphonia]) AND (“Voice Disorders” OR “Dysphonia” OR “voice disorder” OR “voice disturbance” OR “voice disturbances” OR “phonation disorder” OR “phonation disorders” OR “phonatory disorder” OR “phonatory disorders” OR “voice problems” OR “vocal problems” OR “vocal complaints” OR “voice complaints” OR “Functional Dysphonia” OR “Organofunctional Dysphonia” OR “Behavioral Dysphonia” OR “Muscle Tension Dysphonia” OR “Hyperfunctional Dysphonia” OR “Hyperkinetic Dysphonia”:ti,ab,kw) AND (MeSH descriptor: [Voice Training]) AND (“Voice Training” OR “Vocal Training” OR “Voice Trainings” OR “Voice Therapy” OR “Vocal Therapy” OR “Voice Intervention” OR “Vocal Intervention” OR “Voice Rehabilitation” OR “Vocal Rehabilitation” OR “Phonotherapy” OR “Voice exercise” OR “Voice exercises”:ti,ab,kw)
7. ProQuest Dissertations and Theses
ab((“Voice Disorders” OR “Dysphonia”) AND (“Voice Training” OR “Voice Therapy”))
8. Google Scholar
(“Voice Disorders” OR “Dysphonia”) AND (“Voice Training” OR “Voice Therapy”)
9. MedRxiv
(“Voice Disorders” OR “Dysphonia”) AND (“Voice Training” OR “Voice Therapy”)
Footnotes
Declaration of interest: none
Contributor Information
Vanessa Veis Ribeiro, Universidade de Brasília (UnB), Brasília, Distrito Federal, Brazil; Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil. Harvard Medical School; Massachusetts General Hospital, Boston, Massachusetts, United States of America..
Karen Maria de Paula, Universidade de Brasília (UnB), Brasília, Distrito Federal, Brazil..
Dianete Ângela do Valle Gomes, Universidade de Brasília (UnB), Brasília, Distrito Federal, Brazil..
Kállita Souza Batista, Universidade de Brasília (UnB), Brasília, Distrito Federal, Brazil..
Yago Bonfim Viana, Universidade de Brasília (UnB), Brasília, Distrito Federal, Brazil..
Denis de Jesus Batista, Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil; The University of Sydney, Sydney, New South Wales, Australia..
Allan Carlos França da Silva, Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil..
Giovanna Morais Lima, Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil..
Luiz Medeiros de Araujo Lima-Filho, Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil..
Jarrad Harrison Van Stan, Harvard Medical School; Massachusetts General Hospital, Boston, Massachusetts, United States of America..
Leonardo Lopes, Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brazil..
REFERENCES
- 1.Behlau M, Zambon F, Moreti F, Oliveira G, Couto EB Jr. Voice self-assessment protocols: different trends among organic and behavioral dysphonias. J Voice. 2017;31(1):112.e13–112.e27. doi: 10.1016/j.jvoice.2016.03.014. [DOI] [PubMed] [Google Scholar]
- 2.Naunheim MR, DeVore EK, Huston MN, Song PC, Franco RA Jr, Bhattacharyya N. Increasing prevalence of voice disorders in the USA: updates in the COVID era. Laryngoscope. 2024. Aug;134(8):3713–8. doi: 10.1002/lary.31409. [DOI] [PubMed] [Google Scholar]
- 3.House A, Andrews H. The psychiatric and social characteristics of patients with functional dysphonia. J Psychosom Res. 1987;31(4):483–90. doi: 10.1016/0022-3999(87)90006-7. [DOI] [PubMed] [Google Scholar]
- 4.Tierney W, Xiao R, Milstein C. Characterization of functional dysphonia: Pre‐ and post‐treatment findings. Laryngoscope. 2020;131. doi: 10.1002/lary.29358. [DOI] [PubMed] [Google Scholar]
- 5.Ruotsalainen J, Sellman J, Lehto L, Jauhiainen M, Verbeek J. Interventions for treating functional dysphonia in adults. Cochrane Database Syst Rev. 2007;(3):CD006373. doi: 10.1002/14651858.CD006373.pub2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Behlau M Voz: o livro do especialista. Rio de Janeiro: Thieme; 2001. [Google Scholar]
- 7.Anhaia TC, Gurgel LG, Vieira RH, Cassol M. Direct and indirect vocal interventions on teachers: systematic review of the literature. Audiol Commun Res. 2013;18(4):361–6. [Google Scholar]
- 8.Patel RR, Awan SN, Barkmeier-Kraemer J, Courey M, Deliyski D, Eadie T, et al. Recommended protocols for instrumental assessment of voice: American Speech-Language-Hearing Association expert panel to develop a protocol for instrumental assessment of vocal function. Am J Speech Lang Pathol. 2018;27(3):887–905. doi: 10.1044/2018_AJSLP-17-0009. [DOI] [PubMed] [Google Scholar]
- 9.Xu W, et al. Chinese expert consensus for assessment of vocal function: guidelines of the Subspecialty Group of Voice, Society of Otorhinolaryngology Head and Neck Surgery, Chinese Medical Association; Subspecialty Group of Laryngopharyngology, Editorial Board of Chinese Journal of Otorhinolaryngology Head and Neck Surgery. J Voice. 2024;39(2):469–82. [DOI] [PubMed] [Google Scholar]
- 10.Lechien JR, Geneid A, Bohlender JE, Cantarella G, Avellaneda JC, Desuter G, et al. Consensus for voice quality assessment in clinical practice: guidelines of the European Laryngological Society and Union of the European Phoniatricians. Eur Arch Otorhinolaryngol. 2023. Dec;280(12):5459–73. doi: 10.1007/s00405-023-08211-6. [DOI] [PubMed] [Google Scholar]
- 11.Mathew MM, Bhat JS. Soft phonation index - a sensitive parameter? Indian J Otolaryngol Head Neck Surg. 2009. Jun;61(2):127–30. doi: 10.1007/s12070-009-0050-4. Epub 2009 Jun 14.. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Tanaka S, Banno H, Katsuno M, Suzuki K, Suga N, Hashizume A, Mano T, Araki A, Watanabe H, Adachi H, Tatsumi H, Yamamoto M, Sobue G. Distinct acoustic features in spinal and bulbar muscular atrophy patients with laryngospasm. J Neurol Sci. 2014. Feb 15;337(1–2):193–200. [DOI] [PubMed] [Google Scholar]
- 13.Zwirner P, Murry T, Woodson GE. Phonatory function of neurologically impaired patients. J Commun Disord. 1991. Aug;24(4):287–300. doi: 10.1016/0021-9924(91)90004-3. [DOI] [PubMed] [Google Scholar]
- 14.Stepp CE, Hillman RE, Heaton J The impact of vocal hyperfunction on relative fundamental frequency during voicing offset and onset. J. Speech. Lang. Hear. Res. 2010; 53:1220–1226. doi: 10.1044/1092-4388(2010/09-0234). [DOI] [PubMed] [Google Scholar]
- 15.Van Stan JH, Ortiz AJ, Cortes JP, Marks KL, Toles LE, Mehta DD, Burns JA, Hron T, Stadelman-Cohen T, Krusemark C, Muise J, Fox-Galalis AB, Nudelman C, Zeitels S, Hillman RE. Differences in Daily Voice Use Measures Between Female Patients With Nonphonotraumatic Vocal Hyperfunction and Matched Controls. J Speech Lang Hear Res. 2021. May 11; 64(5):1457–1470. doi: 10.1044/2021_JSLHR-20-00538. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Ghasemzadeh Hamzeh, Hillman Robert E., Van Stan Jarrad H., Mehta Daryush D., Effects of Recording Condition and Number of Monitored Days on the Discriminative Power of the Daily Phonotrauma Index, Journal of Speech, Language, and Hearing Research, 10.1044/2024_JSLHR-24-00237, 68, 2, (518–530), (2025). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Hart Tessa, Dijkers Marcel P., Whyte John, Turkstra Lyn S., Zanca Jeanne M., Packel Andrew, Van Stan Jarrad H., Ferraro Mary, and Chen Christine. “A theory-driven system for the specification of rehabilitation treatments.” Archives of Physical Medicine and Rehabilitation 100, no. 1 (2019): 172–180. [DOI] [PubMed] [Google Scholar]
- 18.Peters MDJ, Marnie C, Tricco AC, Pollock D, Munn Z, Alexander L, et al. Updated methodological guidance for the conduct of scoping reviews. JBI Evid Synth. 2020;18(10):2119–26. doi: 10.11124/JBIES-20-00167. [DOI] [PubMed] [Google Scholar]
- 19.Shamseer L, Moher D, Clarke M, Ghersi D, Liberati A, Petticrew M, et al. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015;349:g7647. doi: 10.1136/bmj.g7647. [DOI] [PubMed] [Google Scholar]
- 20.Haddaway NR, Collins AM, Coughlin D, Kirk S. The role of Google Scholar in evidence reviews and its applicability to grey literature searching. PLoS One. 2015;10(9):e0138237. doi: 10.1371/journal.pone.0138237. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Peters MDJ, Godfrey C, McInerney P, Munn Z, Tricco AC, Khalil H. Chapter 11: Scoping Reviews. In: Aromataris E, Munn Z, editors. JBI Manual for Evidence Synthesis. Adelaide: JBI; 2020. doi: 10.46658/JBIMES-20-12. [DOI] [Google Scholar]
- 22.Tricco AC, Lillie E, Zarin W, O’Brien KK, Colquhoun H, Levac D, et al. PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Ann Intern Med. 2018;169(7):467–73. doi: 10.7326/M18-0850. [DOI] [PubMed] [Google Scholar]
- 23.Medronho R. Epidemiologia. Rio de Janeiro: Atheneu; 2009. [Google Scholar]
- 24.Alegria R, Freitas S, Manso M. Effectiveness of voice therapy in patients with vocal fold nodules: a systematic search and narrative review. Eur Arch Otorhinolaryngol. 2020;277:1–16. doi: 10.1007/s00405-020-06059-8. [DOI] [PubMed] [Google Scholar]
- 25.Desjardins M, Halstead L, Cooke M, Bonilha H. A systematic review of voice therapy: what “effectiveness” really implies. J Voice. 2017;31(3):392.e13–392.e32. doi: 10.1016/j.jvoice.2016.10.002. [DOI] [PubMed] [Google Scholar]
- 26.Journal of Voice [Internet]. Philadelphia (PA): The Voice Foundation; c1987–. Available from: https://voicefoundation.org/journal-of-voice/ [Google Scholar]
- 27.Behlau M, Gasparini G. Voice disorders research and treatment in Brazil. ASHA Leader. 2006;11(6):6–8. doi: 10.1044/leader.WB3.11062006.6. [DOI] [Google Scholar]
- 28.Yeakel H, Balouch B, Schmitz J, Alnouri G, Sataloff RT. Gender differences in vocal fold mass treatment. J Voice. 2024;38(2):510–515. doi: 10.1016/j.jvoice.2021.10.002. [DOI] [PubMed] [Google Scholar]
- 29.Baghban K, Golmohamadi G, Asadollahpour F. The worldwide prevalence of voice disorders among schoolteachers: a systematic review and meta-analysis. J Voice. 2025. doi: 10.1016/j.jvoice.2025.04.018. [DOI] [PubMed] [Google Scholar]
- 30.Van Houtte E, Claeys S, Wuyts F, Van Lierde K. The impact of voice disorders among teachers: vocal complaints, treatment-seeking behavior, knowledge of vocal care, and voice-related absenteeism. J Voice. 2011;25(5):570–575. doi: 10.1016/j.jvoice.2010.04.008. [DOI] [PubMed] [Google Scholar]
- 31.Behlau M, Madazio G, Vaiano T, Pacheco C, Badaró F. Voice evaluation – contribution of the speech-language pathologist voice specialist – SLP-V: part A. History of the problem and vocal behaviour data, self-assessment and auditory perceptual judgement. Hear Balance Commun. 2021;19:311–317. doi: 10.1080/21695717.2022020509. [DOI] [Google Scholar]
- 32.Behlau M, Almeida A, Amorim G, Balata P, Bastos S, Cassol M, et al. Reducing the gap between science and clinic: lessons from academia and professional practice – part A: perceptual-auditory judgment of vocal quality, acoustic vocal signal analysis and voice self-assessment. CoDAS. 2022;34. doi:10.1590/. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Timerbulatov I, Savelieva E, Pestova R, Zagidullina I, Timerbulatov R. Assessment of the possibility of acoustic voice analysis. Meditsinskiy sovet (Medical Council). 2025. doi: 10.21518/ms2025-029. [DOI] [Google Scholar]
- 34.Gunjawate D, Chacon A, Nguyen D, Madill C. Vocal tasks for acoustic and/or auditory perceptual analysis for discriminating individuals with and without voice disorders: a systematic review protocol. BMJ Open. 2023;13:e077398. doi: 10.1136/bmjopen-2023-077398. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Lee Y, Kim G, Kwon S. The usefulness of auditory perceptual assessment and acoustic analysis for classifying voice severity. J Voice. 2019. doi: 10.1016/j.jvoice.2019.04.013. [DOI] [PubMed] [Google Scholar]
- 36.Maryn Y, Roy N, De Bodt M, Van Cauwenberge P, Corthals P. Acoustic measurement of overall voice quality: a meta-analysis. J Acoust Soc Am. 2009;126(5):2619–2634. doi: 10.1121/1.3224706. [DOI] [PubMed] [Google Scholar]
- 37.Guzmán M, Bertucci T, Pacheco C, Leiva F, Quintana F, Ansaldi R, et al. Effectiveness of a physiologic voice therapy program based on different semioccluded vocal tract exercises in subjects with behavioral dysphonia: a randomized controlled trial. J Commun Disord. 2020;87:106023. doi: 10.1016/j.jcomdis.2020.106023. [DOI] [PubMed] [Google Scholar]
- 38.Christmann M, Scapini F, De Moraes Lima J, Da Trindade Gonçalves B, Bastilha G, Cielo C. Aerodynamic vocal measurements in female teachers: finger kazoo intensive short-term vocal therapy. J Voice. 2019. doi: 10.1016/j.jvoice.2019.08.018. [DOI] [PubMed] [Google Scholar]
- 39.Estes C, Johnson A. Practical considerations for instrumental acoustic and aerodynamic assessment of voice: discussion points from an open forum of clinicians. Perspect ASHA Spec Interest Groups. 2023. doi: 10.1044/2023_persp-23-00039. [DOI] [Google Scholar]
- 40.Behlau M. The 2016 G. Paul Moore Lecture: lessons in voice rehabilitation: Journal of Voice and clinical practice. J Voice. 2019. doi: 10.1016/j.jvoice.2018.02.020. [DOI] [PubMed] [Google Scholar]
- 41.Torbes T, Da Silva K, Gadenz C, Cassol M. Adherence of patients with dysphonia to voice therapy: systematic review. J Voice. 2020. doi: 10.1016/j.jvoice.2019.04.008. [DOI] [PubMed] [Google Scholar]
- 42.Haddaway NR, Page MJ, Pritchard CC, McGuinness LA. PRISMA2020: an R package and Shiny app for producing PRISMA 2020–compliant flow diagrams, with interactivity for optimised digital transparency and Open Synthesis. Campbell Syst Rev. 2022;18:e1230. doi: 10.1002/cl2.1230. [DOI] [PMC free article] [PubMed] [Google Scholar]