Extreme Vocal Effects Distortion, Growl, Grunt, Rattle, and Creaking as Measured by Electroglottography and Acoustics in 32 Healthy Professional Singers

Vocal effects - also called extreme or extended vocal techniques - with the intention to sound hoarse or rough are widely used as part of many genres and styles of singing, yet scarcely documented in research. Physiological studies detail the involvement of supraglottic structures for the production of vocal effects, yet the acoustic impact of such involvement has not been documented systematically across phonation types.

PURPOSE

To report acoustic measurements and electroglottography-specific measurements for the five rough-sounding vocal effects Distortion, Growl, Grunt, Rattle, and Creaking across phonation types to demonstrate differences between notes with and without vocal effects added.

METHODS

Thirty-two professional singers and singing teachers produced sustained vowels in each of the four vocal modes with alternations of adding and removing the vocal effects. The singers were recorded with a microphone at a constant distance as well as with EGG.

RESULTS

The vocal effects Distortion, Growl, Grunt, Rattle, and Creaking impact the acoustic spectra in separate and systematic ways across genders and phonation types. Each vocal effect impacted the spectrum in specific and particular frequency regions between 0 and 3.5 KHz as well as in higher partials after 12 kHz with statistical significance. EGG-waveforms were un-impacted by most of the vocal effects produced using supraglottic sound sources, whereas Grunt and Creaking conditions did impact EGG-waveform signals, though not consistently between participants. EGG measures confirmed sustained and unchanged Qx and Fx for most conditions, with statically significant changes in noise measurements Harmonic-to-Noise Ratio, Normalised Noise Energy, Relative Average Perturbation, and Cepstral Peak Prominence, despite Sound Pressure Level differing significantly only for a few specific conditions. Singers scored an average of 5,95 on Voice Handicap Index questionnaires and were all reportedly healthy.

CONCLUSIONS

Vocal effects added to phonation produce specific increases and specific decreases in particular frequency regions in a systematic way and can be produced in a healthy and sustainable manner, as measured by Voice Handicap Index. Vocal effects can be added to different phonation types with differing acoustic output and singers were able to sustain and control involvement of the supraglottic sound source(s) independently of phonation type.

Acoustic and Physiologic Correlates of Vocal Effort in Individuals With and Without Primary Muscle Tension Dysphonia

OBJECTIVES

The aims of this study were to determine relationships between vocal effort and (a) acoustic correlates of vocal output and (b) supraglottic compression in individuals with primary muscle tension dysphonia (pMTD) and without voice disorders (controls) in the context of a vocal load challenge.

METHOD

Twenty-six individuals with pMTD and 35 vocally healthy controls participated in a 30-min vocal load challenge. The pre- and postload relationships among self-ratings of vocal effort, various acoustic voice measures, and supraglottic compression (mediolateral and anteroposterior) were tested with multiple regression models and post hoc Pearson's correlations. Acoustic measures included cepstral peak prominence (CPP), low-to-high spectral ratio, difference in intensity between the first two harmonics, fundamental frequency, and sound pressure level (dB SPL).

RESULTS

Regression models for CPP and mediolateral compression were statistically significant. Vocal effort, diagnosis of pMTD, and vocal demand were each significant variables influencing CPP measures. CPP was lower in the pMTD group across stages. There was no statistical change in CPP following the vocal load challenge within either group, but both groups had an increase in vocal effort postload. Vocal effort and diagnosis influenced the mediolateral compression model. Mediolateral compression was higher in the pMTD group across stages and had a negative relationship with vocal effort, but it did not differ after vocal loading.

CONCLUSIONS

CPP and mediolateral supraglottic compression were influenced by vocal effort and diagnosis of pMTD. Increased vocal effort was associated with lower CPP, particularly after vocal load, and decreased mediolateral supraglottic compression in the pMTD group.

Quantification of False Vocal Fold Hyperfunction During Quiet Breathing in Muscle Tension Dysphonia

BACKGROUND/OBJECTIVES

False vocal fold (FVF) hyperfunction during phonation is thought to be a diagnostic sign of primary muscle tension dysphonia (pMTD). However, hyperfunctional patterns with phonation are also observed in typical speakers. This study tested the hypothesis that FVF posturing during quiet breathing, as measured by the curvature of FVF, could differentiate patients with pMTD from typical speakers.

METHODS

Laryngoscopic images were collected prospectively in 30 subjects with pMTD and 33 typical speakers. Images were acquired at the end of expiration and maximal inspiration during quiet breathing, during sustained /i/, and during loud phonation before and after a 30-min vocal loading task. The FVF curvature (degree of concavity/convexity) was quantified using a novel curvature index (CI, >0 for hyperfunctional/convex, <0 for "relaxed"/concave) and compared between the two groups.

RESULTS

At end-expiration, the pMTD group adopted a convex FVF contour, whereas the control group adopted a concave FVF contour (mean CI 0.123 [SEM 0.046] vs. -0.093 [SEM 0.030], p = 0.0002) before vocal loading. At maximal inspiration, the pMTD group had a neutral/straight FVF contour, whereas the control group had a concave FVF contour (mean CI 0.012 [SEM 0.038] vs. -0.155 [SEM 0.018], p = 0.0002). There were no statistically significant differences in FVF curvature between groups in either the sustained voiced or loud conditions. Vocal loading did not change any of these relationships.

CONCLUSIONS

A hyperfunctional posture of the FVFs during quiet breathing especially at end-expiration may be more indicative of a hyperfunctional voice disorder than supraglottic constriction during voicing.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:3449-3454, 2023.

Listeners' Perception of Vocal Effects During Singing

INTRODUCTION

Effective communication is a key feature of vocal music. Singers can communicate during singing by changing their voice qualities to express emotion. Varying acceptable standards are used by performers for voice quality secondary to musical genre. Types of voice qualities that are historically perceived as abusive by some teachers of singing (ToS) and speech-language pathologists (SLPs) are vocal effects. This study investigates the perceptions of vocal effects in professional and nonprofessional listeners (NPLs).

METHODS

Participants (n = 100) completed an online survey. Participants were divided into four professional groups; Classical ToS, Contemporary ToS, SLPs, and NPLs. Participants completed an identification task to assess their ability to identify the use of a vocal effect. Secondly, participants analyzed a singer performing a vocal effect, rated their preferences towards the effect, and gave objective performance ratings using a Likert scale. Finally, participants were asked if they had concerns about the singer's voice. If the participant responded yes, they were asked who they would refer the singer to, a SLP, ToS or medical doctor (MD).

RESULTS

Statistically significant differences were observed in SLPs ability to identify the use of vocal effects compared to classical ToS (P = 0.01), contemporary ToS (P = 0.001) as well as NPLs compared to contemporary ToS (P = 0.009). NPLs were reported to have a lesser rate of concern statistically compared to professional listeners (P = .006). Statically significant differences were found when comparing performance rating scores secondary to preference for the vocal effect when comparisons were larger than one Likert rating interval. With listeners giving higher performance ratings, if they reported higher preference ratings. Finally, no significant differences were identified when comparing referral scores secondary to occupation.

CONCLUSIONS

Findings provide support for the presence of specific biases towards the use of vocal effects although no bias was found in management and care recommendations. Future research is recommended to investigate the nature of these biases.

Extreme Vocals-A Retrospective Longitudinal study of Vocal Health in 20 Professional Singers Performing and Teaching Rough Vocal Effects

BACKGROUND

Rough vocal effects, extreme, or extended vocal techniques to sound intentionally hoarse or rough are an integral part of many genres and styles, and research has recently demonstrated the involvement of supraglottic narrowing and vibrations to produce such sounds. The vocal health of singing with rough vocal effects is poorly documented, especially in a longitudinal manner, while much vocal pedagogy continuously treats the sounds as harming to or dangerous for the vocal mechanism.

OBJECTIVE

To longitudinally investigate the vocal health of professional singers who perform the five rough-sounding vocal effects Distortion, Growl, Grunt, Rattle, and Creaking as part of their singing and teaching.

METHODS

Twenty singers underwent nasoendoscopic examination, filled in SVHI questionnaires, and were assessed by GRBAS with a 14-year interval in a retrospective longitudinal study (from 2007 to 2021). Endoscopic materials were assessed by Reflux Finding Score and a hybrid version of the Stroboscopy Rating Scale.

RESULTS

Singers presented at initiation of study with an average SVHI of 9.2 (±9), which decreased at time of follow up 14 years later to an average of 5.12 (±6). Laryngeal assessments (RFS and SRS) revealed low averages at initiation of study as well as at conclusion of the study with only small fluctuations in averages, with findings mainly relating to arytenoid asymmetry.

CONCLUSION

The participating singers perform and teach rough vocal effects continually and present with healthy laryngeal mechanisms and within-normal SVHI and GRBAS scores. The findings suggest that controlled supraglottic narrowing and techniques to allow for supraglottic structures to engage in vibration as an additional noise source can be performed sustainable and in a healthy manner if performed with correct vocal technique.

Laryngeal Pathologies Associated with the Genre of Singing and Professional Singing Status in a Treatment-Seeking Population

OBJECTIVES/HYPOTHESIS

Singers have high vocal demands and are at increased risk of developing voice disorders. Different singing genres place different technical demands on the voice. However, differences in laryngeal pathology based on genre have not been well-researched. The purpose of this study was to determine the prevalence of laryngeal pathology in different genres of professional and amateur singers who present with a voice complaint.

STUDY DESIGN

Retrospective review.

METHODS

Retrospective review of patients seen at a tertiary laryngology practice. Self-identified singers who reported their primary singing genre and categorized their singing as a full-time job, part-time job, or amateur involvement were included. Type and prevalence of pathology were calculated based on genre and professional status.

RESULTS

Of the 302 self-identified singers, 54% (n = 164) had laryngeal pathology. Among those with pathology, the most common finding was fibrotic lesion (38.4%, 63/164). Genres in which a majority of singers had pathology were other (69.2%, 9/13), choral (64.7%, 11/17), pop (63.2%, 12/19), musical theater (61.4%, 43/70), country (100%, 4/4), and Latin (100%, 2/2). The highest prevalence of pathology was seen in part-time professional singers (62.2%, 41/66) and full-time professionals (60.8%, 62/102), compared to amateurs (45.1%, 60/133).

CONCLUSIONS

Laryngeal pathology is prevalent in singers presenting with a voice complaint. Regardless of genre or professional status, fibrotic lesions were the most common pathological finding. This study provides preliminary data on the prevalence of different laryngeal pathologies found in singers by genre and degree of professional involvement.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:2076-2080, 2021.

Laryngostroboscopic Exploration of Rough Vocal Effects in Singing and their Statistical Recognizability: An Anatomical and Physiological Description and Visual Recognizability Study of Distortion, Growl, Rattle, and Grunt using laryngostroboscopic Imaging and Panel Assessment

OBJECTIVES

To study vocal effects in singing from the pedagogical method complete vocal technique as related to specific and discrete supraglottic structures and activities by means of laryngostroboscopic imaging and panel testing.

STUDY DESIGN

This is a case-control study with a double-panel assessment.

METHODS

Twenty singers were recorded performing four of the rough vocal effects from the method Complete Vocal Technique. Two studies were performed: (1) Laryngostroboscopic examination using a videonasoendoscopic camera system and the Laryngostrobe program; (2) two blind-panel assessments with (a) voice clinicians and (b) singing teachers to investigate the recognizability of the vocal effects in supraglottic structures.

RESULTS

The four investigated vocal effects could be related to particular and discrete vibratory pattern of supraglottic structures; Distortion as vibrations of the ventricular folds, Growl as vibrations of the arytenoid cartilages against the epiglottis, Rattle as the vibration of the arytenoid cartilages against one another, and Grunt as the vibrations of the whole supraglottic structure from level 1-4 at low frequencies with a large amplitude in the vibration of the vocal folds, with particular movement of the aryepiglottic folds. The two panels recognized the vocal effects with 91%/96% accuracy for Distortion, 91%/74% accuracy for Rattle, 90%/66% accuracy for Grunt, and 83%/99% accuracy for Growl, with an overall accuracy of 91%/84%.

CONCLUSION

Vocal effects can be performed, identified, and recognized as particular vibratory patterns of supraglottic structures with no visible pathology in subjects performing the effects.

Aerodynamic Characteristics of Growl Voice and Reinforced Falsetto in Metal Singing

OBJECTIVES

The present study aimed to assess the aerodynamic characteristics of vocally healthy metal singers when producing growl voice or reinforced falsetto.

METHODS

Fifty-four participants (metal singers) were initially enrolled in this study, with 23 meeting the inclusion criteria. Sixteen participants performed growl voice and seven performed reinforced falsetto as a voice resource during metal singing. All participants were asked to undergo rigid laryngeal videostroboscopy to confirm the absence of laryngeal pathology. Then, subjects were aerodynamically assessed while performing growl voice or reinforced falsetto.

RESULTS

Higher glottal airflow rate, sound pressure level, and subglottic pressure (Psub) for growl voice samples compared to vowel production without growl voice (keeping the same fundamental frequency [F0]) were found. Higher Psub, sound pressure level, and glottal resistance for high-pitched reinforced falsetto compared to naïve falsetto (keeping the same F0) were found. No differences for F0 were found for neither growl voice nor reinforced falsetto.

CONCLUSIONS

It seems that growl voice is produced by decreasing vocal folds adduction and increasing Psub, which in turn, promotes an increased airflow rate. Reinforced falsetto is characterized by an increased vocal fold adduction and an increased Psub. A proper resonance strategy in reinforced falsetto and a decreased glottal adduction in growl voice might probably be the factors that contribute to prevent voice problems in singers who use these vocal resources, classically labeled as vocal abuse.

Acoustic Analysis of Voice in Singers: A Systematic Review

PURPOSE

Singers are vocal athletes having specific demands from their voice and require special consideration during voice evaluation. Presently, there is a lack of standards for acoustic evaluation in them. The aim of the present study was to systematically review the available literature on the acoustic analysis of voice in singers.

METHOD

A systematic review of studies on acoustic analysis of voice in singers (PubMed/MEDLINE, CINAHL, Scopus, ProQuest, Cochrane, Ovid, Science Direct, and Shodhganga) was carried out. Key words based on PIO (population-investigation-outcome) were used to develop search strings. Titles and abstracts were screened independently, and appropriate studies were read in full for data extraction.

RESULTS

Of the 895 studies, 26 studies met the inclusion criteria. Great variability was noted in the instruments and task used. Different acoustic measures were employed, such as fundamental frequency, perturbation, cepstral, spectral, dysphonia severity index, singing power ratio, and so forth.

CONCLUSION

Overall, a great heterogeneity was noted regarding population, tasks, instruments, and parameters. There is a lack of standardized criteria for the evaluation of singing voice. In order to implement acoustic analysis as a part of comprehensive voice evaluation exclusively for singers, there is a certain need for methodical sound studies.

Brain activity during phonation in healthy female singers with supraglottic compression: an fMRI pilot study

This pilot study evaluated the usability of functional magnetic resonance imaging (fMRI) to detect brain activation during phonation in healthy female singers with supraglottic compression. Four healthy female classical singers (mean age: 26 years) participated in the study. All subjects had normal vocal folds and vocal characteristics and showed supraglottic compression. The fMRI experiment was carried out using a block design paradigm. Brain activation during phonation and exhalation was analyzed using Brain Voyager software (Brain Innovation B.V., Maastricht, The Netherlands). An fMRI data analysis showed a significant effect of phonation control in the bilateral pre/postcentral gyrus, and in the frontal, cingulate, superior and middle temporal gyrus, as well as in the parietal lobe, insula, lingual gyrus, cerebellum, thalamus and brainstem. These activation areas are consistent with previous reports using other fMRI protocols. In addition, a significant effect of phonation compared to exhalation control was found in the bilateral superior temporal gyrus, and the pre/postcentral gyrus. This fMRI pilot study allowed to detect a normal pattern of brain activity during phonation in healthy female singers with supraglottic compression using the proposed protocol. However, the pilot study detected problems with the experimental material/procedures that would necessitate refining the fMRI protocol. The phonation tasks were not capable to show brain activation difference between high-pitched and comfortable phonation. Further fMRI studies manipulating vocal parameters during phonation of the vowels /a/ and /i/ may elicit more distinctive hemodynamic response (HDR) activity patterns relative to voice modulation.

Using Receiver Operating Characteristic Curve to Define the Cutoff Points of Voice Handicap Index Applied to Young Adult Male Smokers

Voice performance is an inextricable key factor of everyday life. Obviously, the deterioration of voice quality can cause various problems to human communication and can therefore reduce the performance of social skills (relevant to voice). The deterioration could be originated from changes inside the system of the vocal tract and larynx. Various prognostic methods exist, and among them is the Voice Handicap Index (VHI). This tool includes self-reported questionnaires, used for determining the cutoff points of total score and of its three domains relevant to young male Greek smokers. The interpretation of the calculated cutoff points can serve as a strong indicator of imminent or future evaluation by a clinician. Consistent with previous calculation, the VHI can also act as a feedback for smokers' voice condition and as monitoring procedure toward smoking cessation. Specifically, the sample consisted of 130 male nondysphonic smokers (aged 18-33 years) who all participated in the VHI test procedure. The test results (through receiver operating characteristic analysis) concluded to a total cutoff point score of 19.50 (sensitivity: 0.838, 1-specificity: 0). Also, in terms of constructs, the Functional domain was equal to 7.50 (sensitivity: 0.676, 1-specificity: 0.032), the Physical domain was equal to 7.50 (sensitivity: 0.706, 1-specificity: 0.032), and the Emotional domain was equal to 6.50 (sensitivity: 0.809, 1-specificity: 0.048).

Toward Defining "Vocal Constriction": Practitioner Perspectives

OBJECTIVES

This research investigated the terminology used in relation to constriction of the singing voice from a range of practitioner perspectives. It focused on the locality, causes, consequences, management, trends, identification, and vocabulary of constriction. The research aimed to develop a holistic understanding of the term "vocal constriction" from participant experiences and perceptions (N = 10).

METHOD

Data collection occurred through in-depth, semi-structured interviews with a range of voice care professionals. Participants included three professional groups: (1) Ear, Nose, and Throat medical specialists or laryngologists, (2) speech pathologists or speech therapists, and (3) singing teachers. Purposive sampling was used to ensure that the participants from groups 1 and 2 had extensive experience with singers in their practice. The singing teachers were experienced in either classical or contemporary styles, or both.

RESULTS

Participant responses highlighted a discrepancy in preferred terminology, with "constriction" being less favored overall. Several anatomical locations were identified including postural, supraglottic (anteroposterior and false fold), articulatory, and in the intrinsic and extrinsic laryngeal musculature; psychological issues were also identified. Primary causes, secondary causes, and influencing factors were identified. Inefficient technique and poor posture or alignment were considered primary causes; similarly, emotion and anxiety or stress were identified as influencing factors by the majority of participants. There was less uniformity in responses regarding other causes.

CONCLUSIONS

The major findings of this research are the respective participant group distinctions, an uncertainty regarding anteroposterior constriction, and that the location and effects of constriction are individual to the singer and must be considered contextually. A definition is offered, and areas for further research are identified.

Voice Handicap Index and Interpretation of the Cutoff Points Using Receiver Operating Characteristic Curve as Screening for Young Adult Female Smokers

The relationship between smoking and alterations of the vocal tract and larynx is well known. This pathology leads to the degradation of voice performance in daily living. Multiple assessment methods of vocal tract and larynx have been developed, and in recent years they were enriched with self-reported questionnaires such as Voice Handicap Index (VHI). This study determined the cutoff points of VHI's total score and its three domains for young female smokers in Greece. These estimated cutoff points could be used by voice specialists as an indicator for further clinical evaluation (foreseeing a potential risk of developing a vocal symptom because of smoking habits). A sample of 120 female nondysphonic smokers (aged 18-31) was recruited. Participants filled out the VHI and Voice Evaluation Form. VHI's cutoff point of total score was calculated at the value of 19.50 (sensitivity: 0.780, 1-specificity: 0.133). Specifically, the construct domain of functional was 7.50 (sensitivity: 0.900, 1-specificity: 0.217), for physical it was 8.50 (sensitivity: 0.867, 1-specificity: 0.483), and for emotional it was 7.50 (sensitivity: 0.833, 1-specificity: 0.200) through the use of receiver operating characteristic. Furthermore, VHI could be used as a monitoring tool for smokers and as a feedback for smoking cessation.

Computerized Tomography Measures During and After Artificial Lengthening of the Vocal Tract in Subjects With Voice Disorders

PURPOSE

The present study aimed to observe the effect of two types of tubes on vocal tract bidimensional and tridimensional images.

METHODS

Ten participants with hyperfunctional dysphonia were included. Computerized tomography was performed during production of sustained [a:], followed by sustained phonation into a drinking straw, and then repetition of sustained [a:]. A similar procedure was performed with a stirring straw after 15 minutes of vocal rest. Anatomic distances and area measures were obtained from computerized tomography midsagittal and transversal images. Vocal tract total volume was also calculated.

RESULTS

During tube phonation, increases were measured in the vertical length of the vocal tract, oropharyngeal area, hypopharyngeal area, outlet of the epilaryngeal tube, and inlet to the lower pharynx. Also, the larynx was lower, and more closure was noted between the velum and the nasal passage.

CONCLUSION

Tube phonation causes an increased total vocal tract volume, mostly because of the increased cross-sectional areas in the pharyngeal region. This change is more prominent when the tube offers more airflow resistance (stirring straw) compared with less airflow resistance (drinking straw). Based on our data and previous studies, it seems that vocal tract changes are not dependent on the voice condition (vocally trained, untrained, or disordered voices), but on the exercise itself and the type of instructions given to subjects. Tube phonation is a good option to reach therapeutic goals (eg, wide pharynx and low larynx) without giving biomechanical instructions, but only asking patients to feel easy voice and vibratory sensations.

Observational study of differences in head position for high notes in famous classical and non-classical male singers

INTRODUCTION

Differences in classical and non-classical singing are due primarily to aesthetic style requirements. The head position can affect the sound quality. This study aimed at comparing the head position for famous classical and non-classical male singers performing high notes.

METHOD

Images of 39 Western classical and 34 non-classical male singers during live performances were obtained from YouTube. Ten raters evaluated the frontal rotational head position (depression versus elevation) and transverse head position (retraction versus protraction) visually using a visual analogue scale.

RESULTS

The results showed a significant difference for frontal rotational head position.

DISCUSSION AND CONCLUSION

Most non-classical singers in the sample elevated their heads for high notes while the classical singers were observed to keep it around the neutral position. This difference may be attributed to different singing techniques and phonatory system adjustments utilized by each group.