Table 3.
Studies description.
| Reference | Sample size | Study design | Speech sample | Outcome measures | Duration and type of treatment | Results/conclusions | Effectiveness of treatment |
|---|---|---|---|---|---|---|---|
| Ternström et al. (23) | N = 31 amateur choir singers, 9 M and 22 F | RCT: parallel-group | Reading a 3-min passage of prose text | Acoustic analysis (SPL; F0) Were measured for the pre- and post-treatment recordings |
Two groups: 16 in the massage group (30 min), 15 in the CG rested, lying down in silence for the same amount of time | Subjects lowered their F0 by 1.1 semitones and their SPL by 1.0 dB, with very high statistical significance. The drop in F0 was somewhat larger for the males than for the females. The control subjects showed no effect at all | ↑ F0 ↑ SPL |
| Leppänen et al. (24) | N = 60 teachers, 26–57 years, m.a.: 40.6 years 0 M and 60 F | RCT: parallel-group | Sustained vowel/a/for 5 s; reading sample for 1 min at both habitual loudness and loudly | VAS (for a questionnaire about voice quality, ease or difficulty of phonation, and tiredness of the throat); perceptual-auditory analysis; acoustic analyses (F0; jitter; shimmer; Leq; α-ratio). Measurements were at the beginning and end of the autumn school term, before, and after a working day | All subjects received a 3-h VHL. After that they were divided in two groups: VM (five times in 1 h sessions; the first three sessions were given at intervals of 1 week, while the last two sessions were given at intervals of 1 month) and a VHL that received the previous 3-h VHL | The mean F0 (in reading samples) was higher and more difficulty of phonation was reported in the VHL group. Perceived pitch in loud reading increased in the VHL group and decreased in the VM group. In the VM group, the perceived firmness of loud reading decreased (p = 0.026). The results suggest that VM may help in sustaining vocal well-being during a school term | ↑ Perceived pitch, ↑ perceived firmness of loud reading |
| D’haeseleer et al. (25) | N = 16 vocal performers, 19–25 years, m.a.: 21.4 years, 5 M and 16 F | RCT: parallel-group | Sustained vowel/a/ | MPT; Acoustic analysis (F0; jitter; shimmer; noise-to-harmonic ratio); voice range profile; DSI; Self-Evaluations of Vocal Quality Questionnaire. Immediately before and after the therapy or vocal rest, an identical objective voice assessment protocol was performed | Single treatment approach. The experimental group received MCT for 20 min, whereas the CG was instructed to have complete vocal rest for 20 min | In the experimental group a significant difference in DSI was found between the measurement before and after MCT. No differences in DSI were found in the CG between the two measurements. In MCT group, improvements in MPT time and jitter were not significant | ↑ DSI, = MPT, = jitter |
| Anhaia et al. (26) | N = 42 professors, 26–59 years, m.a.: 38 years, 6 M and 36 F | RCT: parallel-group | Sustained vowel/e/and an automatic speech sequence (count from 1 to 20) in regular voice | VAPP; VAS for cervical muscle tension evaluation; perceptual–auditory analysis (GRBASI); acoustic analysis (GNE; shimmer; jitter) | Two groups: perilaryngeal manual massage (G1) or vocal training (G2); 8 sessions (30 min), once a week | Both groups had an improvement in vocal symptoms. No difference in VAPP between groups. The perilaryngeal manual massage provides a slight improvement in professors’ global dysphonia level and reduces cervical tension, which is significantly reflected in self-perceived pain | G1: ↑VAPP, ↑VAS, ↑ perceptual-auditory analysis; ↑ GNE; G2: ↑VAPP, = VAS, = perceptual-auditory analysis, ↑ GNE, ↑ shimmer |
| Kennard, et al. (27) | N = 12 singers, m.a.: 24 years, 7 M and 5 F | RCT: crossover | Reading “Arthur the Rat” | Acoustic analysis (F0 and glottal closing quotient). Singers were measured acoustically immediately before and immediately after each intervention using a laryngograph. After a washout of 6 weeks, participants were switched between groups | Single treatment approach. Two osteopathic treatments: specific laryngeal manipulation (30 min) and postural manual therapy (30 min) | Positive effects of laryngeal manipulation and postural manual therapy in singers. Specific laryngeal manipulation and postural manual therapy showed a significant improvement of F0 (p = 0.018, p = 0.0143, respectively). No differences in glottal closing time | ↑ F0, = glottal closing time |
| Fachinatto et al. (21) | N = 21 singers 17–51 years, m.a.: 26.3 years, 29 M and 0 F | RCT: crossover | Sing 1-min segment of a Gregorian version of the “Hail Mary” prayer | Perceptual–auditory analysis; acoustic analysis (F0; F3; F4; F5); recordings of the singing voice of each participant were taken immediately before and after the procedures. After a washout of 14 days, participants were switched between groups | Single-treatment approach. Two groups: chiropractic spinal manipulative therapy (10 min) and non-therapeutic TENS procedure (10 min) | No differences in the quality of the singing voice of asymptomatic male singers were observed on perceptual audio evaluation or acoustic analysis after a single spinal manipulative intervention of the thoracic and cervical spine | = perceptual audio, = acoustic analysis |
| Silvério et al. (28) | N = 20 w/dysphonia 18–45 years, m.a.: 21.4 years, 0 M and 20 F | RCT: parallel-group | Sustained vowel/a/isolated and after deep inspiration in pitch and usual loudness Spontaneous speech, in speed, articulation, usual pitch, and loudness, answering the questions, “What do you think of your voice?” and “Tell me about your work” | Vocal and laryngeal symptoms (questionnaire); NMSQ; VAS (pain); perceptual–auditory analysis | The volunteers were subdivided into: TENS Group (10 volunteers); LMT Group (10 volunteers). Both groups received 12 sessions of treatment, twice a week (6 weeks), lasting 20 min each | After TENS, there was significant improvement in the “high pitched voice” and “effort to speak” symptoms; there was significantly lower frequency of pain in the posterior neck and shoulder; TENS significantly reduced the intensity of pain in the posterior neck, shoulder, and upper back. The auditory perceptual analysis showed improvement only in the strain parameter after TENS. After LMT, there was improvement of the “sore throat,” significantly lower incidence of pain in the anterior neck, and the pain intensity in the posterior neck decreased. Conclusion. TENS appeared to be a treatment method intended to be used as a complement to voice therapy | After TENS: ↑ “high pitched voice,” ↑ “effort to speak,” ↑ VAS, ↑ perceptual–auditory analysis. After LMT: ↑ “sore throat,” ↑ VAS |
| Yiu et al. (22) | N = 84 w/dysphonia, 20–56 years, 18 M and 66 F | RCT: parallel-group | Sustained vowel/a/(voice range profile); sustained/i/with their tongue protruded at a comfortable pitch level for at least 5 s (laryngoscopy) | Voice range profile (maximum F0 and intensity); Size of vocal fold lesion using laryngoscopy evaluation; VAPP. Pre-treatment baseline measures were taken about an hour before the first acupuncture treatment. Second set of measures were taken 2 h after the last acupuncture session (sixth week; post-treatment), then followed by three assessments, conducted 14, 30, and 90 days after treatment. Participants in the no-treatment group were assessed on the day of enrollment, and at the 6th, 8th, 10th, and 19th week of their participation | Three groups: the genuine acupuncture group received needles puncturing nine voice-related acupoints for 30 min, two times a week for 6 weeks; the sham acupuncture group received blunted needles stimulating the skin surface of the nine acupoints for the same frequency and duration; the no-treatment group did not receive any intervention but attended the assessment sessions | Significant improvement in vocal function, as indicated by the maximum fundamental frequency produced and perceived quality of life, was found in both the genuine and sham acupuncture groups, but not in the no-treatment group. Structural (morphological) improvements were, however, only noticed in the genuine acupuncture group, which demonstrated a significant reduction in the size of the vocal fold lesions | After genuine acupuncture: ↑ voice range profile, ↑ maximum F0, ↑ VAPP, ↑ size of vocal fold lesion. After sham acupuncture: ↑ voice range profile, ↑ Maximum F0, ↑ VAPP, = size of vocal fold lesion. After no-treatment group: = voice range profile, = maximum F0, = VAPP, = size of vocal fold lesion |
Code—CG, control group; Leq, equivalent sound level; F5, fifth formant; F4, fourth formant; F0, fundamental frequency; GNE, glottal noise energy; GRBASI, grade, roughness, breathiness, asteny, strain, instability; ↑, improvement; LMT, laryngeal manual therapy; MCT, manual circumlaryngeal therapy; MPT, maximum phonation time; m.a., mean age; MTD, muscle tension dysphonia; MPQ, musculoskeletal pain questionnaire; =, no changes; NMSQ, nordic musculoskeletal symptoms questionnaire; RCT, randomized controlled trial; SNR, signal-to-noise ratio; SPL, sound pressure level; F3, third formant; TENS, transcutaneous electrical nerve stimulation; VAS, visual analog scale; VAPP, voice activity and participation profile; voice hygiene lecture; VM, Voice MassageTM; w/, with.