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The Role of Vibrato in Group Singing: A Systematic Review
... Voice integration plays a crucial role in choral singing and is one of the important standards for measuring the singing level and artistic achievement of a choral group. Only through continuous practice and exploration can the chorus achieve the perfect realm of sound integration so that the audience can feel the charm and power of music when enjoying the choral performance [15][16][17][18]. ...
Chorus is a polyphonic vocal art. Sound fusion and harmony are an important basis for measuring the quality of the chorus. How to train many chorus members into fusion, harmony and unity of acoustics is the unremitting pursuit of chorus conductors and chorus members. In this paper, after studying the physical properties of sound and the physiological mechanism of its generation, we use the spectrum analysis method based on acoustic theory to quantify the sound fusion of the choir and introduce the base-2FFT algorithm extracted by time to improve the spectrum analysis method, so as to achieve the audio signal identification and noise reduction of the sound fusion. The analysis of the mixed chorus “The Good Place of the Wujin Sand Sea” shows that the chorus members sang by using the method of head voice straight voice, which can do their best to eliminate each person’s singing individuality and timbral characteristics, and integrate the individual timbre into the collective, and sang with a smooth breath, with the amplitude in the range of [-40,40]. In contrast, the choristers sang using the solo state method, the choristers retained their personalities in their singing, did not integrate their colours into the collective, and the sound between the voices was not sufficiently balanced in their singing, with amplitude values between [-80,80]. The use of spectral visualisation allows conductors to control musical elements more accurately in the professional practice of rehearsing choral works.
The purpose of this literature review was to synthesize research related to perceptions of choral tone and to provide implications for future research and praxis. Although considerable research exists on the topic of choral tone, choral music professionals have indicated contradictory philosophies of what makes “good” choral tone. To highlight these contradictions, this literature review includes common interpretations of tone, vocal tone, and choral tone; factors that influence choral tone production; and issues regarding the perception of choral tone. Implications and research-based suggestions for how choral directors may approach choral tone are also shared.
"The relevance of the studied issue is the need to identify the main trends in choral performance, and determine the principles of the work of conductors and choral artists in the context of renewal of the components in this field. The aim of the research is to study the problem of current global trends in the development of choral performance as a complex multifaceted and integral phenomenon. Its practical methods (audio search; audio selection; audio analysis) were used in the research. The aspects of modern choral performance (interdisciplinary; socio-cultural; as well as artistic management; professional training; modern engineering technologies; information and communication space; technologies aimed at preserving human and professional resources) were identified. The current components of activity in the field of modern choral art were established. The directions of modern choral practice were identified (activation of the musical group in the life of society; expansion of traditional executive functions; growth of the genre stylistic palette of the choral repertoire). The system of key modernized methods of interpreting choral works of the 20th and 21st centuries was studied (principles of intonation; the principle of expanding the range; the principle of enriching the technical means of interpretation; the principles of forming the performance texture; the principle of interpreting the verbal text in the context of the choral score; the principle of creating different types of sound). The general features of modern choral performance in Ukraine and in the world were studied. The results can be applied in the process of researching future choral performing practice and preparing the relevant studies. The prospects of research in this field of musical culture are to enrich the theoretical and practical sectors of choral art as a complex system which is open for updates. Keywords: choral art, choir, choral work, performance interpretation, choral genre, choral style, timbre dramaturgy, performance analysis."
This is an 'open access' article - read it here: https://rdcu.be/b55Rj
A growing body of evidence points to a wide range of benefits arising from participation in group singing. Group singing requires participants to engage with each other in a simultaneous musical dialogue in a pluralistic and emergent context, creating a coherent cultural expression through the reflexive negotiation of (musical) meaning manifest in the collective power of the human voice. As such, group singing might be taken—both literally and figuratively—as a potent form of ‘healthy public’, creating an ‘ideal’ community, which participants can subsequently mobilise as a positive resource for everyday life. The experiences of a group of singers (n = 78) who had participated in an outdoor singing project were collected and analysed using a three-layer research design consisting of: distributed data generation and interpretation, considered against comparative data from other singing groups (n = 88); a focus group workshop (n = 11); an unstructured interview (n = 2). The study confirmed an expected perception of the social bonding effect of group singing, highlighting affordances for interpersonal attunement and attachment alongside a powerful individual sense of feeling ‘uplifted’. This study presents a novel perspective on group singing, highlighting the importance of participant experience as a means of understanding music as a holistic and complex adaptive system. It validates findings about group singing from previous studies—in particular the stability of the social bonding effect as a less variant characteristic in the face of environmental and other situational influences, alongside its capacity for mental health recovery. It establishes a subjective sociocultural and musical understanding of group singing, by expanding on these findings to centralise the importance of individual experience, and the consciousness of that experience as descriptive and reflective self-awareness. The ways in which participants describe and discuss their experiences of group singing and its benefits points to a complex interdependence between a number of musical, neurobiological and psychosocial mechanisms, which might be independently and objectively analysed. An emerging theory is that at least some of the potency of group singing is as a resource where people can rehearse and perform ‘healthy’ relationships, further emphasising its potential as a resource for healthy publics.
Background
Voice disorders affect patients profoundly, and acoustic tools can potentially measure voice function objectively. Disordered sustained vowels exhibit wide-ranging phenomena, from nearly periodic to highly complex, aperiodic vibrations, and increased "breathiness". Modelling and surrogate data studies have shown significant nonlinear and non-Gaussian random properties in these sounds. Nonetheless, existing tools are limited to analysing voices displaying near periodicity, and do not account for this inherent biophysical nonlinearity and non-Gaussian randomness, often using linear signal processing methods insensitive to these properties. They do not directly measure the two main biophysical symptoms of disorder: complex nonlinear aperiodicity, and turbulent, aeroacoustic, non-Gaussian randomness. Often these tools cannot be applied to more severe disordered voices, limiting their clinical usefulness.
Methods
This paper introduces two new tools to speech analysis: recurrence and fractal scaling, which overcome the range limitations of existing tools by addressing directly these two symptoms of disorder, together reproducing a "hoarseness" diagram. A simple bootstrapped classifier then uses these two features to distinguish normal from disordered voices.
Results
On a large database of subjects with a wide variety of voice disorders, these new techniques can distinguish normal from disordered cases, using quadratic discriminant analysis, to overall correct classification performance of 91.8% plus or minus 2.0%. The true positive classification performance is 95.4% plus or minus 3.2%, and the true negative performance is 91.5% plus or minus 2.3% (95% confidence). This is shown to outperform all combinations of the most popular classical tools.
Conclusions
Given the very large number of arbitrary parameters and computational complexity of existing techniques, these new techniques are far simpler and yet achieve clinically useful classification performance using only a basic classification technique. They do so by exploiting the inherent nonlinearity and turbulent randomness in disordered voice signals. They are widely applicable to the whole range of disordered voice phenomena by design. These new measures could therefore be used for a variety of practical clinical purposes.
The communicative role of nonlinear vocal phenomena remains poorly understood since they are difficult to manipulate or even measure with conventional tools. In this study parametric voice synthesis was employed to add pitch jumps, subharmonics/sidebands, and chaos to synthetic human nonverbal vocalizations. In Experiment 1 (86 participants, 144 sounds), chaos was associated with lower valence, and subharmonics with higher dominance. Arousal ratings were not noticeably affected by any nonlinear effects, except for a marginal effect of subharmonics. These findings were extended in Experiment 2 (83 participants, 212 sounds) using ratings on discrete emotions. Listeners associated pitch jumps, subharmonics, and especially chaos with aversive states such as fear and pain. The effects of manipulations in both experiments were particularly strong for ambiguous vocalizations, such as moans and gasps, and could not be explained by a non-specific measure of spectral noise (harmonics-to-noise ratio) – that is, they would be missed by a conventional acoustic analysis. In conclusion, listeners interpret nonlinear vocal phenomena quite flexibly, depending on their type and the kind of vocalization in which they occur. These results showcase the utility of parametric voice synthesis and highlight the need for a more fine-grained analysis of voice quality in acoustic research.
Objective: The skill to control pitch accurately is an important feature of performance in singing ensembles as it boosts musical excellence. Previous studies analysing single performance sessions provide inconclusive and contrasting results on whether singers in ensembles tend to use a tuning system which deviates from equal temperament for their intonation. The present study observes the evolution of intonation in a newly formed student singing quintet during their first term of study.
Methods / Design: A semi-professional singing quintet was recorded using head-worn microphones and electrolaryngograph electrodes to allow fundamental frequency (fo) evaluation of the individual voices. In addition, a camcorder was used to record verbal interactions between singers. The ensemble rehearsed a homophonic piece arranged for the study during five rehearsal sessions over four months. Singers practised the piece for 10 minutes in each rehearsal, and performed three repetitions of the same pieces pre- and post- rehearsal. Audio and electrolaryngograph data of the repeated performances, and video recordings of the rehearsals were analysed. Aspects of intonation were then measured by extracting the fo values from the electrolaryngograph and acoustic signal, and compared within rehearsals (pre- and post-) and between rehearsals (rehearsals 1 to 5), and across repetitions (take 1-3). Time-stamped transcriptions of rehearsal discussions were used to identify verbal interactions related to tuning, the tuning strategies adopted, and their location (bar or chord) within the piece.
Results / Discussion: Tuning of each singer was closer to equal temperament than just intonation, but the size of major thirds was slightly closer to just intonation, and minor thirds closer to equal temperament. These findings were consistent within and between rehearsals, and across repetitions. Tuning was highlighted as an important feature of rehearsal during the study term, and a range of strategies were adopted to solve tuning related issues. This study provides a novel holistic assessment of tuning strategies within a singing ensemble, furthering understanding of performance practices as well as revealing the complex approach needed for future research in this area. These findings are particularly important for directors and singers to tailor rehearsal strategies that address tuning in singing ensembles, showing that approaches need to be context driven rather than based on theoretical ideal.
Objectives:
The study aimed to investigate and compare the acoustic and aerodynamic characteristics of choral singers and nonsingers.
Method:
Twenty choral singers and 20 nonsingers in the age range of 20-30 years with no vocal pathology participated in the study. For acoustic analysis, the voice sample was recorded and analyzed using Praat software (Phonetic Sciences, University of Amsterdam, Amsterdam, Netherlands) version 6.0.33 and for aerodynamic evaluation, Helios 401 PC based spirometer (Recorders & Medicare System Pvt. Ltd., Panchkula, Haryana, India) was used.
Results:
The results from acoustic analysis of female groups revealed higher F0 in singers than nonsingers; higher jitter, shimmer, and noise-to-harmonics ratio (NHR) values were obtained for nonsingers compared to singers. Results from acoustic analysis of male groups revealed significantly higher F0 in singers than nonsingers and significantly higher shimmer and NHR values for nonsingers compared to singers. Results from aerodynamic analysis for both male and female groups revealed higher vital capacity, forced vital capacity, and slow vital capacity in singers than nonsingers.
Conclusion:
The results revealed better control over phonatory and respiratory subsystems among singers compared to nonsingers, although the singers were untrained. This could be possible due to the fact that long-term singing practices involving vocal modulation and changes in the breathing pattern, better respiratory control during the expiratory phase among singers. However, as the participants of the singing group are untrained, further studies are required to compare the acoustic and the aerodynamic characteristics with trained singers.
The human singing voice changes throughout the lifespan and there are gender- specific variations that need to be taken into account. Life changes in terms of voice are different for females and males and this paper concentrates on the female singing voice in the context of choral singing. Case-study data from three choristers are presented relating to the changing female voice during puberty as part of a longitudinal study of female choristers in a major English Cathedral Choir School. In addition, discussion is presented on important considerations with respect to the female choral singing voice with a particular focus on specific choral aspects during rehearsals and performance.
This paper presents a novel method combining electrolaryngography and acoustic analysis to detect the onset and offset of phonation as well as the beginning and ending of notes within a sung legato phrase, through the application of a peak-picking algorithm, TIMEX. The evaluation of the method applied to a set of singing duo recordings shows an overall performance of 78% within a tolerance window of 50ms compared with manual annotations performed by three experts. Results seem very promising in light of the state-of-the-art techniques presented at MIREX in 2016 yielding an overall performance of around 60%. The new method was applied to a pilot study with two duets to analyse synchronization between singers during ensemble performances. Results from this investigation demonstrate bidirectional temporal adaptations between performers, and suggest that the precision and consistency of synchronization, and the tendency to precede or lag a co-performer might be affected by visual contact between singers and leader-follower relationships. The outcomes of this paper promise to be beneficial for future investigations of synchronization in singing ensembles.
The advent and now increasingly widespread availability of 3-D printers is transforming our understanding of the natural world by enabling observations to be made in a tangible manner. This paper describes the use of 3-D printed models of the vocal tract for different vowels that are used to create an acoustic output when stimulated with an appropriate sound source in a new musical instrument: the Vocal Tract Organ. The shape of each printed vocal tract is recovered from magnetic resonance imaging. It sits atop a loudspeaker to which is provided an acoustic L-F model larynx input signal that is controlled by the notes played on a MIDI (musical instrument digital interface) device such as a keyboard. The larynx input is subject to vibrato with extent and frequency adjustable as desired within the ranges usually found for human singing. Polyphonic inputs for choral singing textures can be applied via a single loudspeaker and vocal tract, invoking the approximation of linearity in the voice production system, thereby making multiple vowel stops a possibility while keeping the complexity of the instrument in reasonable check. The vocal tract organ offers a much more human and natural sounding result than the traditional Vox Humana stops found in larger pipe organs, offering the possibility of enhancing pipe organs of the future as well as becoming the basis for a 'multi-vowel' chamber organ in its own right.
There has been little research on the acoustic correlates of emotional expression in the singing voice. In this study, two pertinent questions are addressed: How does a singer's emotional interpretation of a musical piece affect acoustic parameters in the sung vocalizations? Are these patterns specific enough to allow statistical discrimination of the intended expressive targets? Eight professional opera singers were asked to sing the musical scale upwards and downwards (using meaningless content) to express different emotions, as if on stage. The studio recordings were acoustically analyzed with a standard set of parameters. The results show robust vocal signatures for the emotions studied. Overall, there is a major contrast between sadness and tenderness on the one hand, and anger, joy, and pride on the other. This is based on low vs high levels on the components of loudness, vocal dynamics, high perturbation variation, and a tendency for high low-frequency energy. This pattern can be explained by the high power and arousal characteristics of the emotions with high levels on these components. A multiple discriminant analysis yields classification accuracy greatly exceeding chance level, confirming the reliability of the acoustic patterns.
Electrolaryngography (Lx) and electroglottography (EGG) are non-invasive methods used to assess human vocal fold vibration and investigate speech and singing. This paper provides a systematic review of evidence-based studies using Lx/EGG in the analysis of the singing voice, identifying and critically appraising the thematic content and the research methodologies of the relevant investigations. Lx/EGG represents a powerful tool for the analysis of the singing voice in medical settings, and in support of research and teaching. Current research in this area is paving the way towards a better comprehension of singing performance.
Objective:
To develop an evidence-based guideline for Peer Review of Electronic Search Strategies (PRESS) for systematic reviews (SRs), health technology assessments, and other evidence syntheses.
Study design and setting:
An SR, Web-based survey of experts, and consensus development forum were undertaken to identify checklists that evaluated or validated electronic literature search strategies and to determine which of their elements related to search quality or errors.
Results:
Systematic review: No new search elements were identified for addition to the existing (2008-2010) PRESS 2015 Evidence-Based Checklist, and there was no evidence refuting any of its elements. Results suggested that structured PRESS could identify search errors and improve the selection of search terms. Web-based survey of experts: Most respondents felt that peer review should be undertaken after the MEDLINE search had been prepared but before it had been translated to other databases. Consensus development forum: Of the seven original PRESS elements, six were retained: translation of the research question; Boolean and proximity operators; subject headings; text word search; spelling, syntax and line numbers; and limits and filters. The seventh (skilled translation of the search strategy to additional databases) was removed, as there was consensus that this should be left to the discretion of searchers. An updated PRESS 2015 Guideline Statement was developed, which includes the following four documents: PRESS 2015 Evidence-Based Checklist, PRESS 2015 Recommendations for Librarian Practice, PRESS 2015 Implementation Strategies, and PRESS 2015 Guideline Assessment Form.
Conclusion:
The PRESS 2015 Guideline Statement should help to guide and improve the peer review of electronic literature search strategies.
Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field [1],[2], and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research [3], and some health care journals are moving in this direction [4]. As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews.
Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in four leading medical journals in 1985 and 1986 and found that none met all eight explicit scientific criteria, such as a quality assessment of included studies [5]. In 1987, Sacks and colleagues [6] evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in six domains. Reporting was generally poor; between one and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement [7].
In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials [8]. In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1).
Box 1: Conceptual Issues in the Evolution from QUOROM to PRISMA
Completing a Systematic Review Is an Iterative Process
The conduct of a systematic review depends heavily on the scope and quality of included studies: thus systematic reviewers may need to modify their original review protocol during its conduct. Any systematic review reporting guideline should recommend that such changes can be reported and explained without suggesting that they are inappropriate. The PRISMA Statement (Items 5, 11, 16, and 23) acknowledges this iterative process. Aside from Cochrane reviews, all of which should have a protocol, only about 10% of systematic reviewers report working from a protocol [22]. Without a protocol that is publicly accessible, it is difficult to judge between appropriate and inappropriate modifications.
The era of big data is coming, and evidence-based medicine is attracting increasing attention to improve decision making in medical practice via integrating evidence from well designed and conducted clinical research. Meta-analysis is a statistical technique widely used in evidence-based medicine for analytically combining the findings from independent clinical trials to provide an overall estimation of a treatment effectiveness. The sample mean and standard deviation are two commonly used statistics in meta-analysis but some trials use the median, the minimum and maximum values, or sometimes the first and third quartiles to report the results. Thus, to pool results in a consistent format, researchers need to transform those information back to the sample mean and standard deviation. In this article, we investigate the optimal estimation of the sample mean for meta-analysis from both theoretical and empirical perspectives. A major drawback in the literature is that the sample size, needless to say its importance, is either ignored or used in a stepwise but somewhat arbitrary manner, e.g. the famous method proposed by Hozo et al. We solve this issue by incorporating the sample size in a smoothly changing weight in the estimators to reach the optimal estimation. Our proposed estimators not only improve the existing ones significantly but also share the same virtue of the simplicity. The real data application indicates that our proposed estimators are capable to serve as “rules of thumb” and will be widely applied in evidence-based medicine.
Vibrato, a small, nevertheless an important component in the singing voice is known to enrich the overall singing voice quality. However, in the perception of overall performance, it is often neglected. Singing performance is often appreciated by a mixed audience of those who love music, but not necessarily sing and other singers who may or may not be teachers of singing.
The objectives of the present study were aimed at investigating singers' and nonsingers' perception of vocal vibrato and its effect on the ratings of singer's overall performance.
Prerecorded audio samples of the chorus of a hymn (How Great Thou Art) as sung by 10 singers (both men and women) were played via a speaker to two groups of judges which consisted of three experienced singers and three experienced nonsingers. The singer judges (SJs) were vocal instructors in Western classical, music theater, pop, and contemporary styles. Seven parameters (presence of vibrato, rate, extent, conspicuousness, quality, periodicity, and type) related to vibrato were evaluated through auditory perception by these two groups of judges on a rating scale developed specifically for the study, and one parameter evaluated singer's overall performance.
Cohen's Kappa statistical analysis was used for inter-rater reliability within groups. Nonsinger judges (NSJs) within the group showed varied ratings as did SJs, yet SJs did have higher agreement than NSJs. Chi-square analysis was used across groups. Both groups were distinct from each other in their perception of vibrato. Ratings of singer's overall performance were not affected for NSJs, but certainly affected for SJ.
It could not be concluded that ratings on singer's overall performance was affected as a result of vibrato. Since vibrato is often over-ridden by the singer's voice. But a rare occasion can arise where a vibrato may not sound pleasant and can affect the listener's perception of the singer's performance. Often a feedback from listeners would help monitor singers' performance.
Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
This paper presents a study on intonation and intonation drift in unaccompanied singing, and proposes a simple model of reference pitch memory that accounts for many of the effects observed. Singing experiments were conducted with 24 singers of varying ability under three conditions (Normal, Masked, Imagined). Over the duration of a recording, ∼50 s, a median absolute intonation drift of 11 cents was observed. While smaller than the median note error (19 cents), drift was significant in 22% of recordings. Drift magnitude did not correlate with other measures of singing accuracy, singing experience, or the presence of conditions tested. Furthermore, it is shown that neither a static intonation memory model nor a memoryless interval-based intonation model can account for the accuracy and drift behavior observed. The proposed causal model provides a better explanation as it treats the reference pitch as a changing latent variable.
Humans interact with the environment through sensory and motor acts. Some of these interactions require synchronization among two or more individuals. Multiple-trial designs, which we have used in past work to study interbrain synchronization in the course of joint action, constrain the range of observable interactions. To overcome the limitations of multiple-trial designs, we conducted single-trial analyses of electroencephalography (EEG) signals recorded from eight pairs of guitarists engaged in musical improvisation. We identified hyper-brain networks based on a complex interplay of different frequencies. The intra-brain connections primarily involved higher frequencies (e.g., beta), whereas inter-brain connections primarily operated at lower frequencies (e.g., delta and theta). The topology of hyper-brain networks was frequency-dependent, with a tendency to become more regular at higher frequencies. We also found hyper-brain modules that included nodes (i.e., EEG electrodes) from both brains. Some of the observed network properties were related to musical roles during improvisation. Our findings replicate and extend earlier work and point to mechanisms that enable individuals to engage in temporally coordinated joint action.
This paper considers the measurement of voice quality variations relating to three different performance styles of early music singing by a trained soprano. In particular, the various outputs available following the collection of electrolaryngographic data are presented along with acoustic analyses based on the acoustic pressure waveform to enable a comparison of the three different singing styles. Voice quality analysis is based on the output from the electrolaryngograph, that enables a measurement of fundamental period to 1μs accuracy to be made, enabling fundamental frequency variations including vibrato to be explored. In addition, the percentage of each cycle for which the vocal folds are in contact is measured and varies between the three voice qualities providing insights into the nature of vocal fold vibration in each case. Acoustic output spectral measures are made that are not only based on traditional wide- and narrow-band but also hearing modelling spectrography. These provide a clear indication as to which portions of the spectrum are most prominent in terms of perception of the three different voice qualities. A number of features resulting from the various analyses distinguish the singing styles, thereby providing evidence that the methods used are appropriate for objective characterisation and differentiation of singing styles in early music.
A multi-track recording of a 16-singer choir of many different choir pieces was done some years ago. In this investigation one piece is chosen and analysed singer by singer concerning intonation, synchronisation, and to what extent the singers of a voice section agree to each other. We try to find objective measures for getting closer to a definition of the so-called "chorus-effect". The results show some expected effects of intonation dispersion and also an unexpected lining up of vibrato.
Accurate tuning is an important aspect of singing in harmony in the context of a choir or vocal ensemble. Tuning and 'pitch drift' are concerning factors in performance for even the most accomplished professional choirs when singing a cappella (unaccompanied). In less experienced choirs tuning often lacks precision, typically because individual singers have not developed appropriate listening skills. In order to investigate accuracy of tuning in ensemble singing situations, a chorally appropriate reference is required against which frequency measurements can be made. Since most basic choral singing involves chords in four parts, a four-part reference template is used in which the fundamental frequencies of the notes in each chord can be accurately set. This template can now be used in experiments where three of the reference parts are tuned in any musical temperament (tuning system), in this case equal and just temperaments, and played over headphones to a singer to allow her/his tuning strategy to be investigated. This paper describes a practical implementation of a four-part choral synthesis system in Pure Data (Pd) and its use in an investigation of tuning of notes by individual singers using an exercise originally written to explore pitch drift in a cappella choral singing.
Fundamental frequency (F-0) estimation for quasiharmonic signals is an important task in music signal processing. Many previously developed techniques have suffered from unsatisfactory performance due to ambiguous spectra, noise perturbations, wide frequency range, vibrate, and other common artifacts encountered in musical signals. In this paper a new two-way mismatch (TWM) procedure for estimating F-0 is described which may lead to improved results in this area. This computer-based method uses the quasiharmonic assumption to guide a search for F-0 based on the short-time spectra of an input signal. The estimated F-0 is chosen to minimize discrepancies between measured partial frequencies and harmonic frequencies generated by trial values of F-0. For each trial F-0, mismatches between the harmonics generated and the measured partial frequencies are averaged over a fixed subset of the available partials. A weighting scheme is used to reduce the susceptibility of the procedure to the presence of noise or absence of certain partials in the spectral data. Graphs of F-0 estimate versus time for several representative recorded solo musical instrument and voice passages are presented. Some special strategies for extending the TWM procedure for F-0 estimations of two simultaneous voices in duet recordings are also discussed.
Abstract Choir acoustics is but one facet of choir-related research, yet it is one of the most tangible. Several aspects of sound can be measured objectively, and such results can be related to known properties of voices, rooms, ears and musical scores. What follows is essentially an update of the literature overview in my Ph.D. dissertation from 1989 of empirical investigations known,to me that deal specifically withthe acoustics of choirs, vocal groups, or choir singers. This compilation of sources is no doubt incomplete in certain respects; nevertheless, it will hopefully prove to be useful for researchers and others interested in choir acoustics. General papers Sacerdote (1957) studied some,aspects of solo singing, but also briefly mentioned the F0 behavior of a quartet of sopranos, apparently consisting of students who,did not quite qualify
Unlike fixed-pitch instruments, the voice requires careful regulation during each note in order to maintain a steady pitch. Previous studies have investigated aspects of singing performance such as intonation accuracy and pitch drift, treating pitch as fixed within notes, while the pitch trajectory within notes has hardly been investigated. The aim of this paper is to study pitch variation within vocal notes and ascertain what factors influence the various parts of a note. The authors recorded five soprano, alto, tenor, bass quartets singing two pieces of music in three different listening conditions, according to whether the singers can hear the other participants or not. After analysing all of the individual notes and extracting pitch over time, the authors observed the following regularities: (1) There are transient parts of approximately 120 ms duration at both the beginning and end of a note, where the pitch varies rapidly; (2) the shapes of transient parts differ significantly according to the adjacent pitch, although all singers tend to have a descending transient at the end of a note; (3) the trajectory shapes of female singers differ from those of male singers at the beginnings of notes; (4) between vocal parts, there is a tendency to expand harmonic intervals (by about 8 cents between adjacent voices); (5) the listening condition had no significant effect on within-note pitch trajectories.
This paper investigates singing interaction by analysis of the factors influencing pitch accuracy of unaccompanied pairs of singers. Eight pairs of singers sang two excerpts either in unison or two-part harmony. The experimental condition varied which singers could hear singing partners. After semi-automatic pitch-tracking and manual checking, this paper calculated the pitch error (PE) and interval error and tested the factors of influence using a one-way analysis of variance and a linear mixed-effects model. The results indicate that: (1) singing with the same vocal part is more accurate than singing with a different vocal part; (2) singing solo has less pPE than singing with a partner; (3) PEs are correlated, as singers adjust pitch to mitigate a partner's error and preserve harmonic intervals at the expense of melodic intervals and absolute pitch; (4) other factors influence the pitch accuracy, including: score pitch, score harmonic interval, score melodic interval, musical background, vocal part, and individual differences.
There is a growing body of academic research aiming to quantify and understand the associated health and well being benefits of group singing. The social interaction is known to strongly contribute to perceived improvements to mental and physical health but there are also indications that singing together elicits better well being outcomes that other community activities. This paper introduces the Vocal Interaction in an Immersive Virtual Acoustic (VIIVA) system, which allows the user to take part in a group singing activity in 360 degree virtual reality, hearing themselves in the recorded venue alongside the other singers. The VIIVA is intended to make group singing accessible to those unable to attend real community choirs but also as a tool for experimental research into the health and well being benefits of group singing. This paper describes the VIIVA system and presents a number of method-ologies and applications which are discussed in relation to three ongoing research projects. Preliminary work indicates that the VIIVA system provides a promising tool with which to study the health and well being benefits of group singing, and in particular to control for the social interactions inherent in real group singing activities.
Objectives:
"Blend" is a defining characteristic of good vocal ensemble performance. To achieve this, directors often consider vibrato as a feature to be controlled and consequently restrict its use. Analysis of individual voices in ensemble situations presents several challenges, including the isolation of voices for analysis from recordings. This study considers vibrato production as a feature that contributes to blend through an ecological study of a vocal quartet.
Methods:
A vocal ensemble was recorded using head-worn microphones and electrolaryngograph electrodes to enable fundamental frequency analysis of the individual voices. The same four-part material was recorded over several weeks of rehearsal to allow analysis of conscious and subconscious changes to vibrato production over time. Alongside the recording of their rehearsal discussions, singers were also asked for opinions on vibrato production in connection with blend.
Results and conclusions:
The results indicate that vibrato is adjusted to some extent by individual singers to improve blend, with some instances of synchrony between voice parts. Some conscious alterations to vibrato were made to improve blend; however, these are not always evident in the data, suggesting that singers' own perceptions of their performance may be influenced by other factors. These findings indicate a need for further studies of vibrato as a feature of blend, particularly in terms of the synergies between expectation and actual production, and potential synchronicity between singers; increased understanding of vibrato in an ensemble setting will lead to more efficient rehearsal techniques and vocal training, and could prevent vocal misuse leading to pathology in the future.
For a 'bel canto' trained singer, 'vibrato' is defined as a periodic variation of the fundamental frequency of the sung note, with an intensity variation of the same period. 'Tremolo' is a variation in the intensity only. The locking of vibrato frequencies in unison soprano choirs has been reported and studied. A 1982 review article on the physics of the singing voice suggests that the pleasing or less pleasing quality of harmony in a vocal duet, for example, depends on whether or not the vibratos of the singers synchronise. This does not appear to have been investigated. Recordings of Dame Joan Sutherland singing the "Flower Duet" from the opera Lakme by Delibes with each of 3 different singers were studied. The powerful SpectraPro software was used for analysis. Our results show one singer locking in phase with Dame Joan, another locking in antiphase and another exhibiting phase wander. It is quite remarkable that such a complicatedly coupled system should behave so like a classically coupled oscillator system, for which in phase, and out of phase locking is possible, as is also phase wander. Psychophysical coupling clearly occurs.
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Objectives/hypothesis:
Singers are often asked to sing with a non-vibrato production. The term non-vibrato is problematic in that it is not possible for a human to sing a tone without fundamental frequency variation. Whether a singer achieves a quality of tone that is perceived as non-vibrato is an aurally subjective matter. The specific aim of this study was to determine when a tone is perceived as non-vibrato by a population of singers, voice teachers, choir directors, and speech pathologists. Using voice samples that exhibit a variety of vibrato rates and extents, the investigators sought to determine (1) if there is a threshold for the perception of non-vibrato tone with regard to vibrato extent; (2) if vibrato rate, given similar vibrato extent, does affect the perceptual threshold of non-vibrato tone; and (3) if there are differences in the perceptual threshold of non-vibrato tone across the different professions of the research subjects.
Study design:
Survey.
Methods:
Participants responded to an online survey featuring 40 randomized samples of soprano voices singing [ɑ] with a variety of vibrato rates and extents. Some samples were repeated to test subject response reliability.
Results and conclusions:
Results indicate that a perceptual threshold exists with regard to vibrato extent. However, vibrato rate significantly affected where this extent threshold occurred for the participants. Vibrato extent and rate work together to affect perception of non-vibrato tone. Significant differences were not found across the different groups.
Objectives:
To examine differences in vibrato rate and extent according to vowel, production type, gender, voice type, and vocal training.
Study design:
Cross-sectional.
Methods:
Four collegiate voice teachers used a common protocol to gather data on habitual, best classical, and nonvibrato singing production of five vowels in 78 male and female vocal majors. Subject age, gender, voice type, academic degree program, number of years of training, and most frequent singing style were compared with mean vibrato rate and mean peak-to-peak vibrato extent for each vowel and for each production condition.
Results:
The high versus low and female versus male comparisons in this study support results found in the literature. Both vibrato rate and vibrato extent were reduced when the singers sang nonvibrato as compared with their habitual and best classical production.
Conclusions:
The mechanisms for reducing vibrato rate and extent need further exploration.
This study seeks to examine how target stimulus timbre, vibrato, pitch, and singer classification affect pitch-matching accuracy.
This is a repeated-measures factorial design.
Source signals were synthesized with a source slope of -12 dB/octave with and without vibrato at each of the pitches, C4, B4, and F5. These source signals were filtered using five formant patterns (A-E) constituting a total of 30 stimuli (5 formant patterns × 3 pitches × 2 vibrato conditions). Twelve sopranos and 11 mezzo-sopranos with at least 3 years of individual voice training were recruited from the University Of Tennessee, Knoxville, School of Music and the Knoxville Opera Company. Each singer attempted to match the pitch of all 30 stimuli presented twice in a random order.
Results indicated that there was no significant effect of formant pattern on pitch-matching accuracy. With increasing pitch from C4 to F5, pitch-matching accuracy increased in midpoint of the vowel condition but not in prephonatory set condition. Mezzo-sopranos moved toward being in tune from prephonatory to midpoint of the vowel. However, sopranos at C4 sang closer to being in tune at prephonatory but lowered the pitch at the midpoint of the vowel. Presence or absence of vibrato did not affect the pitch-matching accuracy. However, the interesting finding of the study was that singers attempted to match the timbre of stimuli with vibrato.
The results of this study show that pitch matching is a complex process affected by many parameters.
Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
The effects of aging on singer's voices were studied in commercial sound recordings of 20 singers, who all had been recorded over a period ranging from their 20s to their 60s. Four recordings were selected, one from each decade. Excerpts from each recording were played to a panel of experts who rated the age of the singer. Rated age showed a significant correlation with real age. The vibrato rate and extent, and the center frequency of a spectrum envelop peak near 3 kHz were measured, and the relation of these variables to rated and real age was examined. A clear correlation between the vibrato characteristics and both real and rated age was found.
“Vocalness”, which indicates correctness of vocalization of singing voice used in western classical opera and lied, is defined in terms of relative intensity of the singing formant. An advantage of vocalness is that its measurement is scarcely affected by the vibrato, inherent in the singing voice. As a result of vocalness measurement for sustained vowel /ah/ sung by 21 female singers, no significant difference was found between the two groups of (A) professional singers, and (B) students of voice and trained chorus singers, whereas a marked difference was found between these groups and the group of beginning amateur chorus singers (C). Thus vocalness is expected to be a helpful measure for the vocalization training of beginners.
The purpose of this study was to assess the preferences of undergraduate college student auditors (N = 139) with respect to a choral sound produced in an anechoic chamber that included a fully resonate singer's formant and choral sound produced in the same chamber using a weaker singer's formant resonance. An ensemble comprised of graduate voice students (N = 8) sang four choral music excerpts. Each excerpt was recorded twice. Singers first employed a full soloistic placement that resulted in a tone with strong upper resonance in the singers' formant range (2 kHz – 4 kHz). The same singers then employed a greatly reduced singer's formant resonance. Recordings were analyzed, then compiled into a stimulus recording for this study. Auditor participants were randomly assigned to one of two listening groups. One group listened to six pairings each of two of the choral music excerpts for a total of twelve trials. For each excerpt, the order of presentation of the non-resonant version versus the resonant version was presented three times in one order and three times in the reverse order. Each of the six trials was randomized with the six trials from the second choral music excerpt. The same procedure was followed for the second two choral music excerpts. In each trial, subjects were asked to indicate that excerpt performed with the tone quality that they liked the best. Responses were cross-tabulated according to participants' musical training: (a) college undergraduate choral or vocal music majors with choral training (N = 49), (b) college undergraduate music majors with instrumental training but no choral training (N = 47), and (c) college undergraduates with no music training (N = 43). Results indicated a significant difference (p < .000) between preferences for non-resonant and resonant tone quality. Examination of the mean scores revealed that auditors overall preferred a non-resonant tone quality (M = 7.95) over a resonant tone quality (M = 4.05). When the three training groups were used as factors, a significant difference of (p < .000) was observed between the choral training group and the instrumental training group. There was also a significant difference (p = .001) between the choral training group and the no music training group. The difference between the instrumental training group and the no music training group was not significant (p = .998). Such results appeared to suggest that not only did most auditors prefer a non-resonant choral tone to a resonant one, but also that choral training seemed to increase that preference. Although results were limited to the particular conditions, participants, and choral music excerpts of this study, these findings were discussed in terms of possible ramifications for choral pedagogy and directions for future research.
Computational approaches for modelling expressive music performance have produced systems that emulate music expression, but few steps have been taken in the domain of ensemble performance. In this paper, we propose a novel method for building computational models of ensemble expressive performance and show how this method can be applied for deriving new insights about collaboration among musicians. In order to address the problem of inter-dependence among musicians we propose the introduction of inter-voice contextual attributes. We evaluate the method on data extracted from multi-modal recordings of string quartet performances in two different conditions: solo and ensemble. We used machine-learning algorithms to produce computational models for predicting intensity, timing deviations, vibrato extent, and bowing speed of each note. As a result, the introduced inter-voice contextual attributes generally improved the prediction of the expressive parameters. Furthermore, results on attribute selection show that the models trained on ensemble recordings took more advantage of inter-voice contextual attributes than those trained on solo recordings.
Experiments on the perception of simultaneously sounding notes (as in polyphonic music) were done using a masking paradigm with stimuli containing two simultaneous notes (a masker and a test note). The stimuli can, both perceptually and conceptually, be considered from two points of view: a frequency or spectral point of view based on the frequency components of the notes, and a temporal point of view based on the temporal envelope of the notes. The results show that both play a role in the perception of two-note stimuli. Spectral cues are relevant when the notes start at the same time and have identical temporal envelopes. Thresholds are in the range of zero to minus 20 dB. When one note starts slightly before the other, however, a much better perception results with very low separation thersholds, down to minus 60 dB. Moreover, these low thresholds are largely independent from non-temporal features of the notes. The onset differences used in the experiments correspond roughly with the asynchronization of simultaneous notes found in performed music. This supports the view that ths asynchronization is an important factor in the perception of the various parts or voices in music.
Under controlled conditions, we assessed acoustically (long-term average spectra) and perceptually (singer survey, listener survey) six performances of an soprano, alto, tenor, and bass (SATB) choir ( N = 27) as it sang the same musical excerpt on two portable riser units (standard riser step height, taller riser step height) with varied dimensions of largely horizontal space (close spacing, lateral spacing, circumambient spacing) between singers. Given previous research that suggested horizontally spread spacing between choristers contributes to chorister perceptions of more efficient vocal production and audience preferences for choral sound, we wondered: (1) if spectra analyses might point to a possible acoustical explanation for auditor preferences; and (2) if increasing the height of riser steps to add more vertical space between rows of singers would affect choir sound.
Statistical analyses of spectra data acquired from an audience position microphone found significant differences ( p < .001) in mean signal amplitudes among the various performances. The taller riser unit appeared to enhance modestly the contributions of horizontally spread lateral and circumambient singer spacing. These effects were most robust (c.2–4dB) in diffusion of higher frequency partials in the 2.4–3.7kHz range in and around the ‘singer’s formant’ frequency region on both riser units, and in 4.7–7.1kHz partials on the tall riser unit.
All choristers (100%) thought horizontal singer spacing influenced choir sound; 92.59% of singers described this perceived influence as ‘moderate’ or ‘much.’ Most choristers (96.29%) thought riser step height influenced choral sound, with 62.95% of singers perceiving this influence as ‘moderate’ or ‘much.’ Singers thought spread spacing contributed to most comfortable vocal production, better hearing of self and ensemble, and best overall choir sound.
Listener ( N = 21) survey results indicated significant preference for the overall sound of the spread singer conditions in close versus spread comparisons.
Choral singing is a popular vocational pastime across cultures. The potential health benefits associated with choral singing, including positive effect on well-being, are a topic of interest in health research. However, anecdotal reports from voice professionals suggest that the unique demands of choral singing may enforce unhealthy singing habits. This study explores suboptimal vocal behaviors that are sometimes associated with choral singing, which include singing outside comfortable pitch range, singing too loudly, and singing too softly for blend.
The relationships between suboptimal choral singing habits, vocal warm-ups (WUs), vocal fatigue, and singing-related well-being were assessed via a 14-item Likert-based response format questionnaire. Participants consisted of 196 attendees of the international World Choir Games. The final study group consisted of 53 male and 143 female international amateur singers aged 10-70.
Results indicated a positive correlation between vocal fatigue and suboptimal singing behaviors (r = 0.34, P < 0.0001). Participants who did not engage in suboptimal singing behavior experienced increased singing-related well-being (r = -0.32, P < 0.0001, N = 141). Vocal WUs were not related to vocal fatigue or singing well-being. Substantially, more participants from this demographic preferred choir over solo singing (X(2)[1, N = 196] = 22.93, P < 0.0001).
Suboptimal choral singing behaviors may result in vocal fatigue and reduction of choral singing well-being and should therefore be considered when examining the effect of choral singing on singing-related well-being and health. Future research will compare the amateurs' perceptions of choral singing with perceptions from professional singers and will look at determinants of choral singing well-being.
Analysis by synthesis is a method that has been successfully applied in many areas of scientific research. In speech research, it has proven to be an excellent tool for identifying perceptually relevant acoustical properties of sounds. This paper reports on some first attempts at synthesizing choir singing, the aim being to elucidate the importance of factors such as the frequency scatter in the fundamental and the formants. The presentation relies heavily on sound examples.
Historically, studies of vocal vibrato have concentrated on pulse rate as being a primary factor in determining whether a given vocal movement is a good or bad vibrato or a tremolo or wobble. More recently, investigators have been studying the extent of frequency variation and amplitude variation around their respective means in order to determine their influence on the perception of vibrato. The present study is an additional attempt to understand the three parameters comprising vibrato, their interrelationship, and their relationship to perception. Samples of sustained sung tones were obtained primarily from recordings. The samples were digitized using a 16-bit A/D converter at a sampling frequency of 10 kHz. Each digitized sample was converted to a useful format for marking purposes in order to derive information on vibrato pulse rate, the mean frequency of the tone, the semitone deviation around the mean, percent frequency deviation and percent amplitude variation around the mean amplitude. Data presentation utilizes representative samples of good vibrato, tremolo and wobble and describes differences in waveforms which may impact on perception.
The basic physical mechanisms of speech production is described. A rich variety of bifurcations and episodes of irregular behaviour are observed. Poincaré sections and the analysis of the underlying attractor suggest that these noise-like episodes are low-dimensional deterministic chaos. Possible implications for the very early diagnosis of brain disorder are discussed.
While most studies that attempted to evaluate vibrato quality examined vocal productions of accomplished singers, very little is known about the characteristics of vibrato among singing students. Therefore, in this study, we performed a preliminary attempt to assess vibrato quality in their production of sustained notes. To that end, the presence and quality of vibrato in 253 sung notes was rated subjectively by five experienced singing teachers. The pitch contour was calculated for each recording, from which we calculated the FFT and the autocorrelation of this contour. Subsequently, a series of features was extracted from these two, and then different statistical methods were applied to examine whether the acoustic features could be used to define predictors that would be in agreement with the perceptual judgments. Given the moderate agreement obtained among judges, these acoustic predictors performed relatively well: vibrato existence was predicted correctly in over 82% of the recordings. The predictor for vibrato quality accounted for 46.5% of the variance of the subjective evaluation of vibrato quality. Due to the novelty of this study in assessing vibrato among students rather than among professional singers, several considerations and limitations, as well as directions for further research are discussed.
Are there general auditory grouping principles that allow the sounds of a single speaker to be grouped together before phonetic categorisation? Four experiments are reported on the use made of a common fundamental frequency or a common starting time in grouping formants together to form phonetic categories. The first experiment shows that the perception of a vowel category is unaffected by formants being excited at different fundamentals or starting at 100-ms intervals. The second and third experiments show no effect of a different fundamental on the combination of the timbres of pairs of formants presented either binaurally or dichotically to form diphthongs. Onset-time also has no effect with binaural presentation. The fourth experiment finds both an effect of grouping formants by a common fundaental using formant trajectories that do not overlap in frequency, and also an effect of onset-time. Neither a common fundamental nor common onset-time is either a necessary or a sufficient condition for formants to be grouped into a common speech category, although they can be shown to exert an influence. Both these variables exert a considerable influence on the number of sounds that subjects report hearing, even under conditions where they do not influence the reported speech category, indicating a dissociation between mechanisms concerned with “how many” sound sources there are, and those concerned with “what” a source consists of.
Frequency and amplitude modulations and their phase relationships in vocal vibrato were investigated in an effort to integrate the current body of sometimes contradictory and confusing observations regarding this vocal phenomenon. A resonance-harmonics interaction alone was found to explain sufficiently the various phase relationships between F0 and amplitude modulations as well as the extent of amplitude modulations for most of the present data and many of the observations reported in the literature. Implications were discussed for physiological, aerodynamic, and perceptual investigations of vocal vibrato as well as for investigations comparing pathologic vocal tremor with vocal vibrato.
Four singers(soprano,alto,tenor, and bass) simultaneously recorded unison /a/ vowels on middle?C (261 Hz) in seven different conditions: No instruction, matching or aggregating vibratos, matching or aggregating a nonvibrato tone quality, matching vowel qualities with and without vibrato, and prescribed instructions for a ??target?? vowel with and without vibrato. A perceptual panel of choral directors, singers, and naive auditors rated the blend or homogeneous quality of randomized samples of the unison vowels. Spectral analyses of the unison /a/ samples indicated varying deviations of the actual frequency of the first 14 partials (0?4000 Hz) from the calculated integer multiples of the fundamental frequency. The tabulated results of the auditors were correlated with the percentage error between actual and calculated partial frequencies. [Work supported by NIH Grant No. R08 DC01150?03.]
An attempt to synthesize singing is presented in which a synthesizer containing five cascaded formants is complemented by two noise generators and fixed filters. The performance is controlled by computers reading the input notation and processing it with pronunciation and musical performance rules. Both solo and choralsinging are synthesized. Various effects will be demonstrated, such as timing of pitch changes and consonants, coloratura, markato, timbre, legato, and multiple pitchsinging. Also, some effects concerning musical expression will be presented.
Results from two experimental investigations on the acoustics of choirs are reported. The first concerns sound‐pressure levels (SPL) inside choirs, and the balance of loudness between a singer’s own voice and the ‘‘reference’’ sound from the rest of the choir. Long‐term SPL averages during rehearsals typically gave 80–100 dB, with little variation between choirs or with position in the choir. The fundamental frequency precision of choirsingers was found to deteriorate abruptly when the reference was too loud. The influence of room acoustics and of the spacing between singers is discussed. The second investigation concerns the effect of spectral variations in the reference sound.Experiments were made primarily with individual singers under laboratory conditions. Changes in vowel quality, and absence/presence of certain partials and of vibrato, were all found to affect somewhat the degree of fundamental frequency agreement between singers. Standard deviation in fundamental frequency between section colleagues in live rehearsal was found to be between 0.10 and 0.15 semitones, or 0.6% and 0.9%. Reference vowels with common partials reinforced by formants were found to increase fundamental frequency precision.