Acoustic cues to femininity and masculinity in spontaneous speech.

The perceived level of femininity and masculinity is a prominent property by which a speaker's voice is indexed, and a vocal expression incongruent with the speaker's gender identity can greatly contribute to gender dysphoria. Our understanding of the acoustic cues to the levels of masculinity and femininity perceived by listeners in voices is not well developed, and an increased understanding of them would benefit communication of therapy goals and evaluation in gender-affirming voice training. We developed a voice bank with 132 voices with a range of levels of femininity and masculinity expressed in the voice, as rated by 121 listeners in independent, individually randomized perceptual evaluations. Acoustic models were developed from measures identified as markers of femininity or masculinity in the literature using penalized regression and tenfold cross-validation procedures. The 223 most important acoustic cues explained 89% and 87% of the variance in the perceived level of femininity and masculinity in the evaluation set, respectively. The median fo was confirmed to provide the primary cue, but other acoustic properties must be considered in accurate models of femininity and masculinity perception. The developed models are proposed to afford communication and evaluation of gender-affirming voice training goals and improve voice synthesis efforts.

Gender-Affirming Voice Training for Trans Women: Acoustic Outcomes and Their Associations With Listener Perceptions Related to Gender.

OBJECTIVES: To investigate acoustic outcomes of gender-affirming voice training for trans women wanting to develop a female sounding voice and to describe what happens acoustically when male sounding voices become more female sounding. STUDY DESIGN: Prospective treatment study with repeated measures. METHODS: N = 74 trans women completed a voice training program of 8-12 sessions and had their voices audio recorded twice before and twice after training. Reference data were obtained from N = 40 cisgender speakers. Fundamental frequency (fo), formant frequencies (F1-F4), sound pressure level (Leq), and level difference between first and second harmonic (L1-L2) were extracted from a reading passage and spontaneous speech. N = 79 naive listeners provided gender-related ratings of participants' audio recordings. A linear mixed-effects model was used to estimate average training effects. Individual level analyses determined how changes in acoustic data were related to listeners' ratings. RESULTS: Group data showed substantial training effects on fo (average, minimum, and maximum) and formant frequencies. Individual data demonstrated that many participants also increased Leq and some increased L1-L2. Measures that most strongly predicted listener ratings of a female sounding voice were: fo, average formant frequency, and Leq. CONCLUSIONS: This is the largest prospective study reporting on acoustic outcomes of gender-affirming voice training for trans women. We confirm findings from previous smaller scale studies by demonstrating that listener perceptions of male and female sounding voices are related to acoustic voice features, and that voice training for trans women wanting to sound female is associated with desirable acoustic changes, indicating training effectiveness. Although acoustic measures can be a valuable indicator of training effectiveness, particularly from the perspective of clinicians and researchers, we contend that a combination of outcome measures, including client perspectives, are needed to provide comprehensive evaluation of gender-affirming voice training that is relevant for all stakeholders.

Gender-Affirming Voice Training for Trans Women: Effectiveness of Training on Patient-Reported Outcomes and Listener Perceptions of Voice.

PURPOSE: Although speech-language pathologists have provided gender-affirming voice training for trans women since the 1970s, evidence for this training's effectiveness remains weak. Our study aimed to redress limitations of earlier studies and evaluate voice training effects on outcomes important to trans women. METHOD: Seventy-four trans women (19-54 years old) who wanted a more female-sounding voice were recruited through two health facilities and provided with an eight- to 12-session voice training program based on contemporary literature, usual clinical practice, and client-centered care principles. Self-reported outcomes and an audio-recorded reading sample were collected 3 months before, immediately before and after, and 3 months after training. Forty cisgender speakers were audio-recorded reading the same sample material as comparison voices. Seventy-nine naive listeners made gender-related voice ratings of an extract from these audio recordings. Training effectiveness was evaluated using group-level analyses (linear mixed-effects models) and individual-level analyses to establish what proportion of participants improved to a predetermined relevant degree. RESULTS: Group-level analyses demonstrated positive training effects, maintained 3 months posttraining, for trans women's vocal satisfaction, perceptions of voice-related social participation, and self- and listener perceptions of their voices. Individual-level analyses also demonstrated positive effects. Two thirds of trans women increased vocal satisfaction to a relevant degree, one third who reported restricted social participation before training reduced this restriction to a relevant degree, and all were rated more female-sounding after training (although not all to a relevant degree). CONCLUSIONS: All trans women participants made progress toward their voice goals and maintained those gains at follow-up. These findings provide evidence that gender-affirming speech-language pathology services warrant prioritization. Further research is warranted to investigate factors predicting outcomes of voice training for trans women.

Exploring Motives and Perceived Barriers for Voice Modification: The Views of Transgender and Gender-Diverse Voice Clients.

PURPOSE: To date, transgender and gender-diverse voice clients' perceptions and individual goals have been missing in discussions and research on gender-affirming voice therapy. Little is, therefore, known about the client's expectations of therapy outcomes and how these are met by treatments developed from views of vocal gender as perceived by cisgender persons. This study aimed to explore clients' individual motives and perceived barriers to undertaking gender-affirming voice therapy. METHOD: Individual, semistructured interviews with 15 transgender and gender-diverse voice clients considering voice therapy were conducted and explored using qualitative content analysis. RESULTS: Three themes were identified during the analysis of the participants' narratives. In the first theme, "the incongruent voice setting the rules," the contribution of the voice on the experienced gender dysphoria is put in focus. The second theme, "to reach a voice of my own choice," centers around anticipated personal gains using a modified voice. The third theme, "a voice out of reach," relates to worries and restricting factors for not being able to reach one's set goals for voice modification. CONCLUSIONS: The interviews clearly indicate a need for a person-centered voice therapy that starts from the individuals' expressed motives for modifying the voice yet also are affirmative of anticipated difficulties related to voice modification. We recommend that these themes should form the basis of the pretherapy joint discussion between the voice client and the speech-language pathologist to ensure therapy goals that are realistic and relevant to the client.

Development and Initial Psychometric Evaluation of the Self-Efficacy Scale for Voice Modification in Trans Women.

OBJECTIVE: To develop a self-efficacy questionnaire for voice modification related to gender affirmation and to examine the internal consistency and test-retest reliability of the questionnaire among a cohort of trans women. METHODS: This study was undertaken in two phases. In phase I, four Speech- Language Pathologists (SLPs) and four trans women informed the development of the Self-Efficacy Scale for Voice Modification in Trans Women (SES-VMTW). In phase II, using classical test theory, data from 31 Australian and 27 Swedish trans women who completed the SES-VMTW twice with an interim period of 3-6 weeks were analyzed for internal consistency and test-retest reliability. During this second phase, the 19 items of the SES-VMTW were subcategorized by consensus among the authors into like groups. RESULTS: Phase I resulted in the 19-item SES-VMTW and four subcategories were identified: 1) Change (items related to changing voice); 2) Perception (items related to the ability to perceive changes in voice; 3) Psychological (items related to engaging in voice practice despite psychological barriers; 4) Logistical (items related to engaging in voice practice despite logistical barriers). In Phase II, initial psychometric analysis was applied to the full questionnaire as well as to the subcategories. The Cronbach's alpha for the full questionnaire (α = 0.86) at both the test and retest timepoints indicates a high level of internal consistency. Item-total correlation analysis indicated that individual items correlated with the questionnaire total score, but that they generally correlated more strongly with the total score for the relevant subcategory. The Cronbach's alpha for the four subcategories of the SES-VMTW were variable but all coefficients exceeded 0.6, thus supporting the reliability of the new scale. Good test-retest reliability was demonstrated for the full questionnaire (intraclass correlation coefficient = 0.84; 95% confidence interval, 0.73-0.90, P < 0.001) and was moderate to good for the four subcategories. CONCLUSION: The findings of the current study are promising, suggesting that both the full SES-VMTW and the four subcategories can provide consistent and reliable insight into self-efficacy for trans women aiming to modify their voice as part of their gender affirmation.

Treatment of Hypophonia in Parkinson's Disease Through Biofeedback in Daily Life Administered with A Portable Voice Accumulator.

OBJECTIVES: The purpose of this study was to assess the outcome following continuous tactile biofeedback of voice sound level administered, with a portable voice accumulator to individuals with Parkinson's disease (PD). METHOD: Nine out of 16 participants with PD completed a 4-week intervention program where biofeedback of voice sound level was administered with the portable voice accumulator VoxLog during speech in daily life. The feedback, a tactile vibration signal from the device, was activated when the wearer used a voice sound level below an individually predetermined threshold level, reminding the wearer to increase voice sound level during speech. Voice use was registered in daily life with the VoxLog during the intervention period as well as during one baseline week, one follow-up week post intervention and 1 week 3 months post intervention. Self-to-other ratio (SOR), which is the difference between voice sound level and environmental noise, was studied in multiple noise ranges. RESULTS: A significant increase in SOR across all noise ranges of 2.28 dB (SD: 0.55) was seen for participants with scores above the cut-off for normal function (>26 points) on the cognitive screening test Montreal Cognitive Assessment (MoCA) (n = 5). No significant increase was seen for the group of participants with MoCA scores below 26 (n = 4). Forty-four percent ended their participation early, all which scored below 26 on MoCA (n = 7). CONCLUSIONS: Biofeedback administered in daily life regarding voice level may help individuals with PD to increase their voice sound level in relation to environmental noise in daily life, but only for a limited subset. Only participants with normal cognitive function as screened by MoCA improved their voice sound level in relation to environmental noise.

Psychometric properties and concurrent validity of the Transgender Congruence Scale (TCS) in the Swedish setting.

The Transgender Congruence Scale (TCS) is a non-binary tool used in Sweden for gender dysphoria (GD) assessment; however, its Swedish version has not been validated. To investigate the psychometric properties of the TCS, its capacity to distinguish individuals with GD and its concurrent validity compared to other scales. Patients with GD (n = 135) and controls (n = 443) filled in a questionnaire containing sociodemographic questions, the TCS, the Utrecht Gender Dysphoria Scale (UGDS), and the Gender Identity/Gender Dysphoria Questionnaire for Adolescents and Adults (GIDYQ-AA). TCS had good discriminatory validity and internal consistency. Patients with GD, stratified by birth-assigned sex, had lower TCS scores compared to controls. Confirmatory factor analysis (CFA) supported the two-factor model of the TCS. Multiple-group CFA suggested measurement invariance between birth-assigned sexes and configural invariance between patients with GD and controls. Area under the ROC curve for birth-assigned males was 0.991 and for females 0.994. A TCS mean value of three provided sensitivity 94.3% and 95.1% as well as specificity 98.6% and 98% for aM and aF, respectively. The TCS was significantly correlated to UGDS and GIDYQ-AA. The TCS may be a valuable tool in the clinical assessment of individuals with GD.

Voice Use in Daily Life Studied With a Portable Voice Accumulator in Individuals With Parkinson's Disease and Matched Healthy Controls.

Purpose The purpose of this work was to study how voice use in daily life is impacted by Parkinson's disease (PD), specifically if there is a difference in voice sound level and phonation ratio during everyday activities for individuals with PD and matched healthy controls. A further aim was to study how variations in environmental noise impact voice use. Method Long-term registration of voice use during 1 week in daily life was performed for 21 participants with PD (11 male, 10 female) and 21 matched healthy controls using the portable voice accumulator VoxLog. Voice use was assessed through registrations of spontaneous speech in different ranges of environmental noise in daily life and in a controlled studio recording setting. Results Individuals with PD use their voice 50%-60% less than their matched healthy controls in daily life. The difference increases in high levels of environmental noise. Individuals with PD used an average voice sound level in daily life that was 8.11 dB (female) and 6.7 dB (male) lower than their matched healthy controls. Difference in mean voice sound level for individuals with PD and controls during spontaneous speech during a controlled studio registration was 3.0 dB for the female group and 4.1 dB for the male group. Conclusions The observed difference in voice use in daily life between individuals with PD and matched healthy controls is a 1st step to objectively quantify the impact of PD on communicative participation. The variations in voice use in different levels of environmental noise and when comparing controlled and variable environments support the idea that the study of voice use should include methods to assess function in less controlled situations outside the clinical setting.

Voice dissatisfaction in individuals with a disorder of sex development.

OBJECTIVE: Changes of sex hormone levels in disorders of sex development (DSD) can affect the body, including the vocal folds, during and after foetal development. The voice is a gender characteristic that may also be affected. There is a lack of knowledge on voice alteration in DSD. To explore this in different forms of DSD, we describe the prevalence of voice alterations and investigate patient satisfaction with voice. DESIGN: The study is part of dsd-LIFE, a multicentre cross-sectional clinical evaluation project assessing the long-term outcomes of surgical, hormonal and psychological interventions in individuals with DSD. PATIENTS: The study included 1040 individuals with different forms of DSD, that is Turner and Klinefelter syndromes, different degrees of gonadal dysgenesis and 46 XY DSD. Participants were recruited through patient advocacy groups and health care. MEASUREMENTS: Satisfaction with voice, Adam's apple, if patient's self-identified gender was mistaken on the phone leading to distress. RESULTS: A vast majority of the participants with DSD (between 58.3% to 82% in various groups) were not satisfied with their voice, and approximately 15% (n = 147) were mistaken on the phone in accordance with self-identified gender. For 102 participants, this caused distress. CONCLUSIONS: We have identified that voice problems are a cause of distress in all forms of DSD. This result needs to be confirmed and compared with controls. We recommend that evaluation of the voice should be included in future international guidelines for management of DSD.

Long-term effects of Lee Silverman Voice Treatment on daily voice use in Parkinson's disease as measured with a portable voice accumulator.

This study examines the effects of an intensive voice treatment focusing on increasing voice intensity, LSVT LOUD® Lee Silverman Voice Treatment, on voice use in daily life in a participant with Parkinson's disease, using a portable voice accumulator, the VoxLog. A secondary aim was to compare voice use between the participant and a matched healthy control. Participants were an individual with Parkinson's disease and his healthy monozygotic twin. Voice use was registered with the VoxLog during 9 weeks for the individual with Parkinson's disease and 2 weeks for the control. This included baseline registrations for both participants, 4 weeks during LSVT LOUD for the individual with Parkinson's disease and 1 week after treatment for both participants. For the participant with Parkinson's disease, follow-up registrations at 3, 6, and 12 months post-treatment were made. The individual with Parkinson's disease increased voice intensity during registrations in daily life with 4.1 dB post-treatment and 1.4 dB at 1-year follow-up compared to before treatment. When monitored during laboratory recordings an increase of 5.6 dB was seen post-treatment and 3.8 dB at 1-year follow-up. Changes in voice intensity were interpreted as a treatment effect as no significant correlations between changes in voice intensity and background noise were found for the individual with Parkinson's disease. The increase in voice intensity in a laboratory setting was comparable to findings previously reported following LSVT LOUD. The increase registered using ambulatory monitoring in daily life was lower but still reflecting a clinically relevant change.

Effects of Gender-confirming Pitch-raising Surgery in Transgender Women a Long-term Follow-up Study of Acoustic and Patient-reported Data.

OBJECTIVES: Transgender women often seek to feminize their voice so that it becomes congruent with their gender identity. Many receive voice therapy (VT) with good results. Some also need pitch-raising surgery. The purpose of this study was to investigate long-term effects and to compare outcomes between cricothyroid approximation (CTA) and glottoplasty (GP). METHODS: This study included retrospective data from 24 patients (35-67 years). Eleven patients had undergone CTA and 13 had undergone GP. Audio recordings were performed in a sound-treated booth and patients answered questionnaires before and after VT, post surgery, and at 1-year follow-up. Fundamental frequency (fo) measures were extracted from voice range profiles (VRPs) and speech range profiles (SRPs) and were compared with cisgender data. RESULTS: Minimum fo in VRP increased significantly only after CTA (95 to 123 Hz). Maximum fo in VRP was significantly lowered after GP (765 to 652 Hz), even more after CTA (677 to 475 Hz). Speaking mean fo increased significantly after VT and post surgery, and was thereafter stable (CTA 167 Hz, GP 169 Hz). The maximum fo in the SRP increased only after VT. The frequency ranges were strongly reduced after CTA. Patients were in general satisfied at follow-up and rated the GP outcomes more favorably than CTA. CONCLUSIONS: Both surgical methods have advantages and disadvantages. The very restricted speaking and physiological frequency ranges, which do not favor an optimal female voice, were mainly found after the irreversible CTA. Thus, CTA is no longer performed at our hospital, whereas surgical techniques based on GP are being developed further. We strongly recommend the use of VRPs to evaluate treatment effects.

Resonance Tube Phonation in Water-the Effect of Tube Diameter and Water Depth on Back Pressure and Bubble Characteristics at Different Airflows.

OBJECTIVES: Resonance tube phonation with tube end in water is a voice therapy method in which the patient phonates through a glass tube, keeping the free end of the tube submerged in water, creating bubbles. The purpose of this experimental study was to determine flow-pressure relationship, flow thresholds between bubble types, and bubble frequency as a function of flow and back volume. METHODS: A flow-driven vocal tract simulator was used for recording the back pressure produced by resonance tubes with inner diameters of 8 and 9 mm submerged at water depths of 0-7 cm. Visual inspection of bubble types through video recording was also performed. RESULTS: The static back pressure was largely determined by the water depth. The narrower tube provided a slightly higher back pressure for a given flow and depth. The amplitude of the pressure oscillations increased with flow and depth. Depending on flow, the bubbles were emitted from the tube in three distinct types with increasing flow: one by one, pairwise, and in a chaotic manner. The bubble frequency was slightly higher for the narrower tube. An increase in back volume led to a decrease in bubble frequency. CONCLUSIONS: This study provides data on the physical properties of resonance tube phonation with the tube end in water. This information will be useful in future research when looking into the possible effects of this type of voice training.

Vocal Behavior in Environmental Noise: Comparisons Between Work and Leisure Conditions in Women With Work-related Voice Disorders and Matched Controls.

OBJECTIVES: This study aimed to assess vocal behavior in women with voice-intensive occupations to investigate differences between patients and controls and between work and leisure conditions with environmental noise level as an experimental factor. METHODS: Patients with work-related voice disorders, 10 with phonasthenia and 10 with vocal nodules, were matched regarding age, profession, and workplace with 20 vocally healthy colleagues. The sound pressure level of environmental noise and the speakers' voice, fundamental frequency, and phonation ratio were registered from morning to night during 1 week with a voice accumulator. Voice data were assessed in low (≤55 dBA), moderate, and high (>70 dBA) environmental noise levels. RESULTS: The average environmental noise level was significantly higher during the work condition for patients with vocal nodules (73.9 dBA) and their controls (73.0 dBA) compared with patients with phonasthenia (68.3 dBA) and their controls (67.1 dBA). The average voice level and the fundamental frequency were also significantly higher during work for the patients with vocal nodules and their controls. During the leisure condition, there were no significant differences in average noise and voice level nor fundamental frequency between the groups. The patients with vocal nodules and their controls spent significantly more time and used their voices significantly more in high-environmental noise levels. CONCLUSIONS: High noise levels during work and demands from the occupation impact vocal behavior. Thus, assessment of voice ergonomics should be part of the work environmental management. To reduce environmental noise levels is important to improve voice ergonomic conditions in communication-intensive and vocally demanding workplaces.

Transmasculine People's Voice Function: A Review of the Currently Available Evidence.

OBJECTIVES: This study aims to evaluate the currently available discursive and empirical data relating to those aspects of transmasculine people's vocal situations that are not primarily gender-related, to identify restrictions to voice function that have been observed in this population, and to make suggestions for future voice research and clinical practice. METHODS: We conducted a comprehensive review of the voice literature. Publications were identified by searching six electronic databases and bibliographies of relevant articles. Twenty-two publications met inclusion criteria. Discourses and empirical data were analyzed for factors and practices that impact on voice function and for indications of voice function-related problems in transmasculine people. The quality of the evidence was appraised. RESULTS: The extent and quality of studies investigating transmasculine people's voice function was found to be limited. There was mixed evidence to suggest that transmasculine people might experience restrictions to a range of domains of voice function, including vocal power, vocal control/stability, glottal function, pitch range/variability, vocal endurance, and voice quality. CONCLUSIONS: More research into the different factors and practices affecting transmasculine people's voice function that takes account of a range of parameters of voice function and considers participants' self-evaluations is needed to establish how functional voice production can be best supported in this population.

Long-Term Follow-Up of Patients with Spasmodic Dysphonia and Improved Voice despite Discontinuation of Treatment.

OBJECTIVE: To evaluate voice function in patients with adductor spasmodic dysphonia (AdSD) who discontinued botulinum toxin (BTX) treatment because they felt that their voice had improved sufficiently. PATIENTS AND METHODS: Twenty-eight patients quit treatment in 2004, of whom 20 fulfilled the inclusion criteria for the study, with 3 subsequently excluded because of return of symptoms, leaving 17 patients (11 males, 6 females) included in this follow-up study. A questionnaire concerning current voice function and the Voice Handicap Index were completed. Audio-perceptual voice assessments were done by 3 listeners. The inter- and intrarater reliabilities were r > 0.80. RESULTS: All patients had a subjectively good stable voice, but with differences in their audio-perceptual voice assessment scores. Based on the pre-/posttreatment auditory scores on the overall degree of AdSD, patients were divided into 2 subgroups showing more and less improvement, with 10 and 7 patients, respectively. The subgroup with more improvement had shorter duration from the onset of symptoms until the start of BTX treatment, and included 7 males compared to only 4 males in the subgroup with less improvement. CONCLUSION: It seems plausible that the symptoms of spasmodic dysphonia may decrease over time. Early intervention and male gender seem to be important factors for long-term reduction of the voice symptoms of AdSD.

Magnetic Resonance Imaging of the Vocal Folds in Women With Congenital Adrenal Hyperplasia and Virilized Voices.

PURPOSE: Women with congenital adrenal hyperplasia (CAH) may develop a virilized voice due to late diagnosis or suboptimal suppression of adrenal androgens. Changes in the vocal folds due to virilization have not been studied in vivo. The purpose was to investigate if the thyroarytenoid (TA) muscle is affected by virilization and correlate findings to fundamental frequency (F0). METHOD: A case-control study using magnetic resonance imaging and voice recordings. Four women with CAH with virilized voices (26-40 years), and 5 female and 4 male controls participated. Measurements of cross-sectional TA muscle area, vocal fold length, vocal tract length, and acoustic analyses of F0 were performed. RESULTS: Women with CAH had larger cross-sectional TA muscle area than female control subjects and smaller than male controls. A significant negative correlation was found between TA muscle area and mean F0. The patients had a smaller physiological voice range than both female and male controls. CONCLUSION: Data from our small study suggest that a larger TA muscle area is strongly associated with a lower F0 and thus the anatomical explanation for a female virilized voice, suggesting an androgen effect on the vocal folds. The findings from the present study need to be confirmed in a larger study.

Effects on Voice Fundamental Frequency and Satisfaction with Voice in Trans Men during Testosterone Treatment-A Longitudinal Study.

OBJECTIVES: To investigate effects of testosterone treatment regarding voice virilization, voice problems, and voice satisfaction in transsexual female-to-male individuals, referred to as trans men. STUDY DESIGN: Longitudinal. METHODS: Fifty trans men, diagnosed with transsexualism, 18-64 years, met the inclusion criteria. Voice data before treatment and after 3, 6, or 12 months were available from 49 participants, and for 28 participants also after 18 and/or 24 months of treatment. Digital audio recordings of speech range profiles and voice range profiles were carried out in a sound-treated booth following clinical routines. Acoustic analyses of fundamental frequency (F0) and sound pressure level were made. Endocrine data and answers from questionnaires concerning voice function and voice problems were collected from medical records. RESULTS: Mean F0 and mode F0 of the habitual voice decreased significantly after 3 months, 6 months, and up to 12 months, when group data were congruent with reference data for males. Mean F0 was 125 Hz after 12 months with a large interindividual variation. Sound pressure level values did not change significantly. Voice satisfaction correlated with lower F0 values. Twenty-four percent of the participants reported voice symptoms, for example, vocal instability and fatigue, and had received voice therapy. F0 values did not correlate with androgen levels. CONCLUSIONS: Most trans men developed a male voice and were satisfied. However, it is important to detect the substantial group of trans men with voice problems and with insufficient voice virilization and who may need voice therapy. Therefore, we recommend systematic voice assessments during testosterone treatment.

Motor-Learning-Based Adjustment of Ambulatory Feedback on Vocal Loudness for Patients With Parkinson's Disease.

OBJECTIVES: To investigate how the direct biofeedback on vocal loudness administered with a portable voice accumulator (VoxLog) should be configured, to facilitate an optimal learning outcome for individuals with Parkinson's disease (PD), on the basis of principles of motor learning. STUDY DESIGN: Methodologic development in an experimental study. METHODS: The portable voice accumulator VoxLog was worn by 20 participants with PD during habitual speech during semistructured conversations. Six different biofeedback configurations were used, in random order, to study which configuration resulted in a feedback frequency closest to 20% as recommended on the basis of previous studies. RESULTS: Activation of feedback when the wearer speaks below a threshold level of 3 dB below the speaker's mean voice sound level in habitual speech combined with an activation time of 500 ms resulted in a mean feedback frequency of 21.2%. CONCLUSIONS: Settings regarding threshold and activation time based on the results from this study are recommended to achieve an optimal learning outcome when administering biofeedback on vocal loudness for individuals with PD using portable voice accumulators.

The Flow and Pressure Relationships in Different Tubes Commonly Used for Semi-occluded Vocal Tract Exercises.

This experimental study investigated the back pressure (P(back)) versus flow (U) relationship for 10 different tubes commonly used for semi-occluded vocal tract exercises, that is, eight straws of different lengths and diameters, a resonance tube, and a silicone tube similar to a Lax Vox tube. All tubes were assessed with the free end in air. The resonance tube and silicone tube were further assessed with the free end under water at the depths from 1 to 7 cm in steps of 1 cm. The results showed that relative changes in the diameter of straws affect P(back) considerably more compared with the same amount of relative change in length. Additionally, once tubes are submerged into water, P(back) needs to overcome the pressure generated by the water depth before flow can start. Under this condition, only a small increase in P(back) was observed as the flow was increased. Therefore, the wider tubes submerged into water produced an almost constant P(back) determined by the water depth, whereas the thinner straws in air produced relatively large changes to P(back) as flow was changed. These differences may be taken advantage of when customizing exercises for different users and diagnoses and optimizing the therapy outcome.

Voice Disorders in Teacher Students-A Prospective Study and a Randomized Controlled Trial.

OBJECTIVES: Teachers are at risk of developing voice disorders, but longitudinal studies on voice problems among teachers are lacking. The aim of this randomized trial was to investigate long-term effects of voice education for teacher students with mild voice problems. In addition, vocal health was examined prospectively in a group of students without voice problems. METHODS: First-semester students answered three questionnaires: one about background factors, one about voice symptoms (Screen6), and the Voice Handicap Index. Students with voice problems according to the questionnaire results were randomized to a voice training group or a control group. At follow-up in the sixth semester, all students answered Screen6 again together with four questions about factors that could have affected vocal health during their teacher education. The training group and the control group also answered the Voice Handicap Index a second time. RESULTS: At follow-up, 400 students remained in the study: 27 in the training group, 54 in the control group, and 319 without voice problems at baseline. Voice problems had decreased somewhat more in the training group than in the control group, but the difference was not statistically significant (P = 0.1). However, subgroup analyses showed significantly larger improvement among the students in the group with complete participation in the training program compared with the group with incomplete participation. Of the 319 students without voice problems at baseline, 14% had developed voice problems. CONCLUSIONS: Voice problems often develop in teacher students. Despite extensive dropout, our results support the hypothesis that voice education for teacher students has a preventive effect.