Facial bone vibration in resonant voice production

Resonant Voice: Perceptual and Acoustic Analysis After an Intensive Lessac Kinesensic Training Workshop

OBJECTIVE

To investigate whether actors' and actresses' voices post an Intensive Lessac Kinesensic Training Workshop - ILKTW can be perceptually identified as more resonant, and to assess if the Acoustic Voice Quality Index (AVQI), the Acoustic Breathing Index (ABI), and their acoustic measures are able to indicate the classified voices as more resonant.

METHODS

Eight vocally healthy English first-language actors and actresses, participants of the same ILKTW, were asked to sustain the vowel /a/ and to read a piece of the Rainbow Passage, pre and postworkshop, at a self-selected habitual frequency and intensity. The readings were divided into initial and final parts, both with 34 syllables, and combined with the vowel /a/ (3s). The pre and postworkshop recordings (pairs of the initial and final parts followed by the /a/ vowel) of each participant were randomly presented to a voice expert who rated the samples as more resonant or similar. The same samples were analyzed using the AVQI and ABI scripts.

RESULTS

87,5% of the initial parts and 100% of the final in postworkshop were rated by the voice expert as more resonant. Tilt was higher for the postworkshop initial parts (P = 0.036), but a correlation with the perceptual rating wasn't found. HNR was higher (P = 0.018) and jitter was lower (P = 0.017) for the postworkshop final parts. The statistical analysis comparing the perceptive and acoustic data for the final samples couldn't be applied.

CONCLUSION

It seems that the ILKTW has a positive impact on the development of a resonant voice and that the perceptual auditory rating was more effective to describe resonant voices than the AVQI, ABI, and its acoustic measures.

Indexing Cognitive Resource Usage for Acquisition of Initial Voice Therapy Targets

PURPOSE

The purpose of this study was to index cognitive resource usage for acquisition of initial targets of two common voice therapy techniques (resonant voice therapy [RVT] and conversation training therapy [CTT]) based on the theorized depletion effect (i.e., when an initial task requiring high cognitive load leads to poorer performance on a subsequent task).

METHOD

Eleven vocally healthy participants, ages 23-41 years, read aloud the Rainbow Passage and produced consonant-vowel resonant targets (/mi, ma, mu/) followed by a baseline computerized Stroop task and a 15-min washout. Following this baseline period, participants watched and interacted with two videos instructing them in RVT or CTT initial targets. After viewing each video and practicing the associated vocal skills, participants rated the degree of mental effort required to engage in the target vocal technique on a modified Borg scale. Participants recorded their attempts at RVT on /mi, ma, mu/ and CTT on the Rainbow Passage, which were later rated by three voice-specialized speech-language pathologists as to how representative they were of each respective target technique. Changes in fundamental frequency and average auditory-perceptual ratings from baseline were examined to determine if participants adjusted their technique from RVT and CTT baseline to acquisition.

RESULTS

Performance on the Stroop task was, on average, worse post CTT than post RVT, but both post-CTT and post-RVT Stroop scores were poorer than baseline. These results suggest that both treatment techniques taxed cognitive resources but that CTT was more cognitively taxing than RVT. However, despite differences in raw averages, no statistically significant differences were found between the baseline, post-CTT, and post-RVT Stroop scores, likely due to the small sample size. Participant ratings of mental effort for CTT and RVT were statistically similar. Likewise, poorer post-RVT Stroop scores were associated with participants' greater perceived mental effort with RVT acquisition, but there was no significant association between mental effort ratings for CTT acquisition and post-CTT Stroop scores. Significantly higher fundamental frequency and perceived ratings of the accuracy of technique from baseline to acquisition for both CTT and RVT were found, providing evidence of vocal behavior changes as a result of each technique.

CONCLUSIONS

Brief exposure to initial treatment tasks in CTT is more cognitively depleting than initial RVT tasks. Results also indicate that vocally healthy participants are able to make a voice change in response to a brief therapy prompt. Finally, participant-rated measures of mental effort and secondary measures of cognitive depletion do not always correlate.

Effects of Resonant Voice Therapy on Perceptual and Acoustic Source and Tract Parameters - A Preliminary Study on Indian Carnatic Classical Singers

PURPOSE

The aim of the study was to examine the effects of resonant voice therapy (RVT) on the vocal resonance of trained Carnatic singers. The specific objectives were to evaluate the effects of resonant voice therapy on the auditory perceptual judgments and acoustic source and tract parameters before and after RVT on phonation and sung voice samples.

METHOD

Six vocally healthy trained Carnatic singers, three males and three females aged 18-25 years (M = 23; S.D = 2.09) participated in the study. All the participants were assigned to a 21-days-long Resonance Voice Therapy (RVT) training program. The participants' pre and post training phonation and sung samples were subjected to auditory perceptual analysis and acoustic analysis.

RESULTS

The results revealed that the post training auditory perceptual ratings of the phonation task showed a statistically significant difference from the pre training scores (Z= 2.35; P = 0.019). While for the singing task, the post training perceptual ratings were not significantly different from the pre training perceptual rating scores (Z= 2.66; P = 0.08). A significant difference was observed between the pre and post training values for all the measured acoustic parameters of the phonation task. In singing task, though the fundamental frequency, third and fourth formant frequencies showed no significant difference in the pre and post training conditions (P > 0.05), the parameter of- difference between the first formant frequency and the fundamental frequency showed a significant decrease (P = 0.028).

CONCLUSION

The effects of resonant voice production led to a high vocal economy, as evidenced from the improved source and filter acoustic parameters. Indication for formant tuning through vocal tract modifications, probably an enlarged pharyngeal area resulting in increased resonant voice quality in both phonation and singing tasks, is inferred from these results.

Long-term Average Spectrum and Nasal Accelerometry in Sentences of Differing Nasality and Forward-Focused Vowel Productions Under Altered Auditory Feedback

OBJECTIVES AND BACKGROUND

To investigate whether voice focus adjustments can alter the audio-vocal feedback and consequently modulate speech/voice motor control. Speaking with a forward-focused voice was expected to enhance audio-vocal feedback and thus decrease the variability of vocal fundamental frequency (F0).

MATERIALS AND METHOD

Twenty-two healthy, untrained adults (10 males and 12 females) were requested to sustain vowel /a/ with their natural focus and a forward focus and to naturally read the nasal, oral, and mixed oral-nasal sentences in normal noise-masked auditory conditions. Meanwhile, a miniature accelerometer was externally attached on the noise to detect the nasal vibrations during vocalization. Audio recordings were made and analyzed using the long-term average spectrum (LTAS) and power spectral analysis of F0.

RESULTS

Compared with naturally-focused vowel production and oral sentences, forward-focused vowel productions and nasal sentences both showed significant increases in nasal accelerometric amplitude and the spectral power within the range of 200∼300 Hz, and significantly decreased the F0 variability below 3 Hz, which has been reported to be associated with enhanced auditory feedback in our previous research. The auditory masking not only significantly increased the low-frequency F0 variability, but also significantly decreased the ratio of the spectral power within 200∼300 Hz to the power within 300∼1000 Hz for the vowel and sentence productions. Gender differences were found in the correlations between the degree of nasal coupling and F0 stability as well as in the LTAS characteristics in response to noise.

CONCLUSIONS

Variations in nasal-oral acoustic coupling not only change the formant features of speech signals, but involuntarily influence the auditory feedback control of vocal fold vibrations. Speakers tend to show improved F0 stability in response to a forward-focused voice adjustment.

Contributions of Forward-Focused Voice to Audio-Vocal Feedback Measured Using Nasal Accelerometry and Power Spectral Analysis of Vocal Fundamental Frequency

PURPOSE

The spectral powers of the modulations of vocal fundamental frequency (f _o) less than 3 Hz (low-frequency power, LFP) and between 3 and 8 Hz (middle-frequency power, MFP) had been established to indicate the audio-vocal feedback status and vocal efficiency of a speaker, and a resonant voice may enhance the auditory-vocal feedback. This study aims to determine whether the auditory feedback can be augmented by a forward and resonant voice and therefore contribute to the modulations of f _o variability.

METHOD

Vocal signals and accelerometric signals of lateral nasal cartilage were obtained from 27 healthy adults who, respectively, sustained vowels /a/ and /i/ with their habitual speaking voice and with a forward-focused voice under three auditory conditions: natural hearing (N0), high-level noise exposure (N90), and low-level noise exposure (N60). Nasal skin vibrations were measured using a nasal accelerometry to reflect voice resonance status. Vocal intensity and f _o variability were also analyzed to show the auditory-vocal interactions under varied conditions of auditory feedback and voice resonance.

RESULTS

In both N0 and N90 conditions, forward-focused voice showed a significantly lower LFP than the speakers' habitual voice. In addition, LFP of f _o would significantly increase during natural voice production as the voice feedback was greatly masked by high-intensity noise; however, with a forward-focused voice, the noise-induced variation in LFP was significantly decreased. Under N90, MFP significantly decreased during forward-focused voice production compared with that measured during natural voice production. The stability of f _o modulations was not adversely affected by N60.

CONCLUSION

The results support the idea that vocalizing with a forward-focused voice enhance the auditory feedback of the speaker's own voice and, thus, reduce the variability of f _o during sustained phonation, especially when vocalizing in the high noise condition.

Influence of nasal cavities on voice quality: Computer simulations and experiments

Nasal cavities are known to introduce antiresonances (dips) in the sound spectrum reducing the acoustic power of the voice. In this study, a three-dimensional (3D) finite element (FE) model of the vocal tract (VT) of one female subject was created for vowels [a:] and [i:] without and with a detailed model of nasal cavities based on CT (Computer Tomography) images. The 3D FE models were then used for analyzing the resonances, antiresonances and the acoustic pressure response spectra of the VT. The computed results were compared with the measurements of a VT model for the vowel [a:], obtained from the FE model by 3D printing. The nasality affects mainly the lowest formant frequency and decreases its peak level. The results confirm the main effect of nasalization, i.e., that sound pressure level decreases in the frequency region of the formants F₁-F₂ and emphasizes the frequency region of the formants F₃-F₅ around the singer's formant cluster. Additionally, many internal local resonances in the nasal and paranasal cavities were found in the 3D FE model. Their effect on the acoustic output was found to be minimal, but accelerometer measurements on the walls of the 3D-printed model suggested they could contribute to structure vibrations.

Vocal fold nodules: A disorder of phonation organs or auditory feedback?

OBJECTIVE

Increasing evidence supports that auditory feedback of one's own voice closely relates to real-time adjustments of vocal control. Previous studies highlighted that the low-frequency modulations of below 3 Hz (LFM) embedded in vocal fundamental frequency (F0) showed a reflex-like response to altered auditory inputs. However, the auditory feedback control of different vocal disorders remains unclear.

DESIGN

A cross-sectional, case-controlled study.

SETTING

A tertiary medical centre.

PARTICIPANTS

Sustained vocalisations of vowel/a/ from adult healthy controls and patients with vocal fold nodules, vocal fold polyps and vocal fold cysts, respectively. The vocalisations were made at a comfortable pitch and at the intensity of 70 ~ 80 dBC under the following four auditory conditions: natural hearing, 90-dBC speech noise, 10-dBC enhanced feedback of self-produced voice and both the noise and voice feedback.

MAIN OUTCOME MEASURES

Power spectral analysis of F0 contour of sustained vowel.

RESULTS

Patients with vocal fold nodules presented with different audio-vocal feedback behaviour and audio-vocal response to speech noise from the other two vocal pathologies of vocal fold polyp and vocal fold cyst as well as the healthy controls (P < .001, one-way ANOVA).

CONCLUSION

The vocal fold nodules may be not only a vocal fold disease but also a disease caused by abnormal audio-vocal feedback. Moreover, the distinct audio-vocal feedback of vocal fold nodules could be revealed by power spectral analysis of vocal fundamental frequencies. Although further investigations are necessary, adjustments of audio-vocal feedback behaviour may provide a new insight and benefit to the treatment of vocal fold nodules in the future.

A systematic review of resonant voice therapy

PURPOSE

The purpose of this study is to systematically review the literature on resonant voice therapy and to evaluate the level of evidence on the effectiveness of using resonant voice therapy in treating dysphonia.

METHOD

Refereed journal papers from 1974 to 2014 were retrieved and reviewed by two independent reviewers using the keywords "Humming, Resonance, Resonant Voice, Semi-occluded or closed tube phonation" using available database systems. Quality of evidence was evaluated by using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULT

Thirteen papers met the search criteria. Nine papers were selected by the two reviewers. Two of the papers were randomised-controlled studies and the other seven were observational studies. At least four types of resonant voice therapies were described. They included the Lessac-Madsen Resonant Voice Therapy, Y-Buzz, Resonance Therapy and Humming. The overall level of quality of evidence was graded as "moderate".

CONCLUSION

There were limited studies that investigated the effectiveness of resonant voice therapy. Most studies were small-scale uncontrolled observational studies with the inclusion of only small samples or specific populations. There is clearly a need for more large-scale randomised controlled studies with a wider range of populations to provide further evidence on the effectiveness of resonant voice training for different populations.

Combined Use of Standard and Throat Microphones for Measurement of Acoustic Voice Parameters and Voice Categorization

OBJECTIVE

The aim of the present study was to evaluate the reliability of the measurements of acoustic voice parameters obtained simultaneously using oral and contact (throat) microphones and to investigate utility of combined use of these microphones for voice categorization.

MATERIALS AND METHODS

Voice samples of sustained vowel /a/ obtained from 157 subjects (105 healthy and 52 pathological voices) were recorded in a soundproof booth simultaneously through two microphones: oral AKG Perception 220 microphone (AKG Acoustics, Vienna, Austria) and contact (throat) Triumph PC microphone (Clearer Communications, Inc, Burnaby, Canada) placed on the lamina of thyroid cartilage. Acoustic voice signal data were measured for fundamental frequency, percent of jitter and shimmer, normalized noise energy, signal-to-noise ratio, and harmonic-to-noise ratio using Dr. Speech software (Tiger Electronics, Seattle, WA).

RESULTS

The correlations of acoustic voice parameters in vocal performance were statistically significant and strong (r = 0.71-1.0) for the entire functional measurements obtained for the two microphones. When classifying into healthy-pathological voice classes, the oral-shimmer revealed the correct classification rate (CCR) of 75.2% and the throat-jitter revealed CCR of 70.7%. However, combination of both throat and oral microphones allowed identifying a set of three voice parameters: throat-signal-to-noise ratio, oral-shimmer, and oral-normalized noise energy, which provided the CCR of 80.3%.

CONCLUSIONS

The measurements of acoustic voice parameters using a combination of oral and throat microphones showed to be reliable in clinical settings and demonstrated high CCRs when distinguishing the healthy and pathological voice patient groups. Our study validates the suitability of the throat microphone signal for the task of automatic voice analysis for the purpose of voice screening.