Vibratory and perceptual measurement of resonant voice

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.

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.

Semioccluded Vocal Tract Exercises: Changes in Laryngeal and Pharyngeal Activity During Stroboscopy

OBJECTIVE

The purpose of this study was to compare the changes in laryngeal activity from baseline during three different semioccluded vocal tract exercises (SOVTs).

STUDY DESIGN

This is a prospective case-series study.

METHODS

Transnasal stroboscopy was performed while four singers performed three SOVTs (straw phonation, lip trill, and tongue trill) to evaluate laryngeal changes during the execution of SOVTs. Evaluations using a modified Stroboscopy Evaluation Rating Form captured the following parameters: amplitude of vocal fold movement, mucosal wave, phase closure, glottal closure, anterior-posterior vocal tract constrictions, medial-lateral vocal tract constrictions, laryngeal ascension, and pharyngeal constriction during a pitch glide.

RESULTS

The parameters that changed from baseline, as well as the direction and magnitude of change that occurred across SOVTs, varied within and between each subject. All the singers benefited from at least one SOVT, but no single SOVT benefited all four singers.

CONCLUSIONS

Although SOVTs result in endoscopic and stroboscopic changes that might be considered beneficial, the results indicate marked variability across SOVTs and singers in terms of the laryngeal and pharyngeal adjustments induced by the exercises. Singing teachers and Speech Language Pathologists (SLPs) may need to more carefully assess the impact of specific SOVTs when deciding which one(s) to prescribe as a teaching or therapeutic exercise.

A taxonomy of voice therapy

PURPOSE

Voice therapy practice and research, as in most types of rehabilitation, is currently limited by the lack of a taxonomy describing what occurs during a therapy session (with enough precision) to determine which techniques/components contribute most to treatment outcomes. To address this limitation, a classification system of voice therapy is proposed that integrates descriptions of therapeutic approaches from the clinical literature into a framework that includes relevant theoretical constructs.

METHOD

Literature searches identified existing rehabilitation taxonomies/therapy classification schemes to frame an initial taxonomic structure. An additional literature search and review of clinical documentation provided a comprehensive list of therapy tasks. The taxonomy's structure underwent several iterations to maximize accuracy, intuitive function, and theoretical underpinnings while minimizing redundancy. The taxonomy was then used to classify established voice therapy programs.

RESULTS

The taxonomy divided voice therapy into direct and indirect interventions delivered using extrinsic and/or intrinsic methods, and Venn diagrams depicted their overlapping nature. A dictionary was developed of the taxonomy's terms, and 7 established voice therapy programs were successfully classified.

CONCLUSION

The proposed taxonomy represents an important initial step toward a standardized voice therapy classification system expected to facilitate outcomes research and communication among clinical stakeholders.

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.