Friday, 11 January 2013

­­David Munrow: thoughts on vibrato and a glimpse into his record collection

Edward Breen,           Department of Music,  York University paper.
  1. Introduction: literature on vibrato consulted by Munrow
  2. The catalyst for Munrow’s essay
  3. Munrow’s views
  4. Method
  5. Results
  6. Discussion
  7. Interpreting the results
  8. Conclusions
  9. Bibliography
  10. Biographical note: Ed Breen


This paper explores the literature and discography that David Munrow used as the basis for his own opinions on vibrato. He collated his findings in an unpublished paper entitled, simply, ‘Vibrato’.
In his paper Munrow outlined some of the arguments about vibrato that he encountered in print and began to relate them to a number of recordings. However, without access to laboratory equipment he was unable to undertake a detailed analysis of the sort that can now be done easily with modern sound editing and analysis software. As such, the limits of his approach become apparent when modern techniques are applied. This chapter relates measurements taken from the recordings to Munrow’s own aural observations as set down in his essay.

1. Introduction: literature on vibrato consulted by Munrow

Carl Seashore at the University of Iowa presided over one of the first scientific accounts of vibrato in the 1930s and such was the detail and thoroughness of his study that it is still cited in the latest editions of major music dictionaries.1 It was not, however, the first study of its kind as Seashore acknowledged when he co-authored an overview of previous work at the end of his study.2 One of the most striking among the surveyed papers was by Max Schoen, the first investigator of vibrato to make use of the University of Iowa’s laboratory equipment.3 Schoen concentrated on the varying pitch of vibrato using experimental techniques that he had been developing since 1921 when he first began his studies into pitch variations in voices.4 By developing a ‘Tonoscope’ (basically a kind of stroboscopic technique) Schoen was able to record surprisingly thorough measurements of the vibrato in recordings of ‘five world-famous opera singers’ performing the Bach-Gounod Ave Maria. Yet just six years later Carl Seashore was already able to expand on Schoen’s data thanks to advances in both electrical recording and photographic techniques; furthermore, he was able to indentify and consider other types of vibrato besides pitch-vibrato.
The wider programme of Studies in the Psychology of Music, of which the vibrato studies form just a part, is one that mirrors current trends in performance-practice analysis due to its emphasis on empirical measurement. Like many studies since, Seashore’s laboratory at the University of Iowa was pursuing the aim of ‘recording adequately the musical performance.’5 Seashore implies that he saw this project as a mixture of musical and psychological studies where scientific methods applied to recorded sound could heighten a listener’s understanding of what they were hearing. For example, he mentions in his introduction an instance where ‘the same form of vibrato expresses both quiet and excited emotion.’6 Here he means that the same measurable parameters of vibrato were observed in two instances regardless of their differing contexts. This ruthlessly objective stance illustrates the way in which we must read his observations. One of the chief claims for his objective approach was that ‘it clears up the historical controversies as to what the vibrato is and should be by laying down objective and verifiable definitions, analyses and principles.’7 A measure of the success of this venture can be seen in one of the definitions that Harold Seashore (son of Carl) proposed for vibrato:
The vibrato in music is a periodic pulsation, generally involving pitch, intensity, and timbre, which produces a pleasing flexibility, mellowness and richness of tone.8
Understanding that vibrato was more than just an oscillation of pitch was a notable advance in the 1930s yet this discovery was still not fully acknowledged by the writers of Grove’s dictionary more than two decades later.9 Even though it generated this groundbreaking definition of vibrato, the work from Seashore’s laboratory had obvious shortcomings.
Despite claims of universality by including categories such as ‘primitive music’ the main focus of these studies was on ‘artistic singing’ evident in Milton Metfessel’s paper: ‘The Vibrato in Artistic Voices’10 [My italics]. Here an ‘artistic’ voice appears to be one which employs an obvious amount of vibrato and, of course, is in keeping with the vocal fashions of the 1920s. It is easy, nearly a century after some of these experiments were performed, to comment on fashions in vocal performance but we must remember that at the time of writing, Metfessel did not have a long tradition of audio recording to survey and as a result was probably much less aware of broader trends in vocal performance outside of the mainstream ‘stars’ who were deemed suitable for marketing by record companies.
Such is the uniformity in the style of singing measured by Metfessel that he is led to surmise confidently that ‘… almost every artistic tone has a vibrato.’11 And on another occasion he tells us: ‘Most singers cannot sing a tone that would have any semblance of desirability without using the vibrato.’12 This suggests that it is probably the vibrato that makes the tone ‘artistic’, or at least contributes an essential component to the tone so that it may be classified as artistic. Either way, it does not tell us how it is decided what passes for either ‘desirable’ or ‘artistic’ and as such is an unexpectedly subjective statement for a study that claims to be objective.
Yet even if he cannot tell us quite what makes a voice artistic, Metfessel does impart something of great interest about the way he observes how listeners receive vibrato:
There are three rival camps on the point of vibrato desirability. There are those who object to any kind of vocal pulsation, whether vibrato or tremolo; those who maintain that vibrato is acceptable in its place on tones which naturally would tremble; and those who champion the vibrato unreservedly.13
From this it is clear that judgments of taste and value were assigned to vibrato in the early part of the twentieth century that in turn indicate that this was not an era of singing when every listener admired the same sort of voice; since Metfessel also tells us that vibrato has been dividing opinions for a least a century, we know that this situation was not a new one.
Having described what vibrato is in terms of sound waves, Metfessel then turns his attention to how the vibrato is created as he attempts to explain how vibrato can be taught in singing lessons. First of all he introduces the concept of ‘involuntary vibrato’ where the possessor is not aware of having vibrato and cannot sing a desirable tone without vibrato; yet he reminds us that vibrato is not a universal human trait. So, before training, some voices have vibrato and some do not. Metfessel claims all voices can be trained to use vibrato and tells us something of the way in which this can be done:
The vocal muscles producing vibrato must reach a certain stage in their development before they can function in that capacity. With some the muscles develop quicker than with others; but probably if they are going to function involuntary at all they will do so during adolescence.14
We can, therefore, take it that vibrato was understood by Metfessel as a muscular action which, due to the under-development of a child’s whole physique (not necessarily just the larynx), is not usually seen before adolescence. What the research considered in this particular essay finds that it cannot do however, is to identify a single muscle-group as being responsible. Rather, Metfessel reports that cases of both laryngeal and diaphragmatic vibrato were observed as well as a combination of the two. In a survey of research from other sources, as well as his own teaching and observation, Metfessel concludes that in training the vibrato:
It is not a matter of voluntarily fluctuating the muscles, but of letting the muscles fluctuate themselves […] the correct muscle-set will be known when the muscles fluctuate. Once the right position is achieved the kinesthetic clues for it will become familiar so that it is not difficult to get the correct muscular adjustment at will repeatedly.15
Vibrato, therefore is a learned and deliberate device employed by the ‘artistic’ singer which also occurs naturally in many suitably muscularly-relaxed voices, albeit to a lesser extent. The importance of vibrato can be divined from Seashore’s 1936 study when he says: ‘All recognized professional singers sing with a pitch vibrato in about 95% or more of their tones.’16 This not only neatly illustrates how widespread the practice was at Seashore’s time of writing but further hints towards his definition for the phrase ‘recognized professional singers.’
Munrow mentions little (if anything) which is obviously gleaned from the studies by Seashore et al despite drawing attention to these studies in his introduction. However, he specifically mentions a second work: the ‘Vibrato’ entry in Willi Apel’s 1944 Harvard Dictionary of Music, another work which also references Seashore. After defining vibrato in stringed instruments as ‘a slight fluctuation of pitch produced on sustained notes by an oscillating motion of the left hand’, Apel chooses to focus on the discrepancy between the use of the terms vibrato and tremolo in singers.17 Vibrato, he explains, is historically a reiteration of the same pitch but, at the time he was writing, is used by singers to refer to ‘a scarcely noticeable wavering of the tone’ which does not result in a noticeable fluctuation of pitch. If this wavering of tone were to ‘degenerate into a real wobble’ then such an ‘unwelcome effect’ is what singers refer to as tremolo even though, historically, that too means something else.18 We can read into this that a voice has vibrato, according to Apel, when pitch fluctuation is hardly noticeable and tremolo when it is too noticeable.
Another source, frequently quoted by Munrow in his essay, is Robert Donnington’s ‘Vibrato’ entry in Grove’s Dictionary of Music and Musicians, 1954. Here, Donnington offers a definition of vibrato as:
A slight and more or less rapid fluctuation of pitch for expressive purposes.19
Interestingly, this definition, like that by Apel, refrains from taking into account the complexity of vibrato as exhibited in rate, intensity or timbre such as was measured and discussed by the Seashore studies, even though both authors reference this earlier work. But such a focus on pitch fluctuation does tally with the observation, above, that Seashore made concerning the profligate use of pitch vibrato in the tones of professional singers. Donnington also divides his entry between stringed instruments and the voice, going further than Apel to separate wind instruments also. These divisions allow him the opportunity to discuss the many techniques of vibrato such as rocking one or more fingers on the string of an instrument or by fluctuating the air supply to a wind instrument (which he remarks is known as a tremulant on the organ).
However incomplete his first definition may appear to be, Donnington’s description of vocal vibrato does go on to classify ‘a comparable fluctuation of intensity’ as a tremolo, explaining that the nomenclature for vibrato and tremolo have been reversed from their usual instrumental meanings in the case of singers. Singing teachers, he explains, warn against the fluctuation of pitch (something that Apel also points out as a danger) preferring a fluctuation of intensity which, despite being a tremolo (like the organ stop), is called a vibrato by singers. Thus, the pitch-vibrato gets the title of ‘tremolo’ and, as such, carries negative connotations. Here he is in perfect agreement with Apel.
Donnington’s Grove entry is expanded in his 1963 book The Interpretation of Early Music from which Munrow photocopied two pages and bundled them with his essay notes thus making it the most modern piece of writing considered.20 Donnington quotes Thomas Mace’s Musick’s Monument in both of his pieces and includes the description of vibrato on the lute which is here called ‘The sting’. Both entries also contain a quotation from Carl Flesch’s The Art of Violin Playing:
From a purely theoretic standpoint, the vibrato, as a means for securing a heightened urge for expression, should only be employed when it is musically justifiable.21
Munrow has annotated his photocopy of The Interpretation of Early Music with the words ‘musically justifiable’ where they are cut off on the page-turn, suggesting that they hold some importance or interest for him. Certainly, in his Grove entry Donnington records his final thoughts as:
Current opinion tends to disfavour the true vibrato unconditionally, but to encourage the tremolo or singer’s ‘vibrato’, provided that it is consciously and skilfully controlled and used with restraint for deliberately expressive purposes.22
Donnington suggests that the use of vocal vibrato is usually an intensity (breath pressure) vibrato and suggests that even this type of vibrato is encountered too frequently and without thought as to musical context.

2. The catalyst for Munrow’s essay

Vocal vibrato was the subject of an exchange of letters in The Musical Times in 1969 and 1970, beginning with Jerome Roche’s review of the album Monteverdi and his Contemporaries by Denis Stevens and the Academia Monteverdiana.23 In his review Roche complained that his enjoyment of the music was marred by what he deemed ‘excessive’ vibrato in the singing of the five soloists. He added that ‘… questions such as the singing of pure thirds in triads […] cannot be given proper consideration with such general vibrato.’24 He then chose, as an example, the last cadence of Gesualdo’s Luci serene where he thought that the bass should have supported the harmony rather than wobbling.
A few issues later, Denis Stevens refuted the charge of excessive vibrato and even went as far as to measure it on electronic equipment, finding that ‘the speed of the individual vibratos never falls below the accepted seven per second, and that deviation from pitch is less than ±3%’ proving, in his opinion, that the lines are never obscured.25 He also pointed out that his singers could not have been using excessive vibrato because they only used it for the embellishment of key moments: ‘I asked the singers for vibrato on the final chord of Gesualdo’s madrigal because the words are more e non langue, indicating a climax both musical and sexual.’26 Roche replied in the same issue that ‘MT readers need not be blinded by the science […], for on these matters the ear is, thankfully, the ultimate judge.’27
And then the critic Norman Suckling entered the fray:
The Gesualdo passage pointed by Professor Stevens may indicate a sexual climax, but that is no excuse for performing it so as to sound like the kind of noises that people would make when undergoing such a climax.28 [my emphasis]
What do we learn from these letters? Firstly, we learn that Roche is objecting to ‘such general vibrato’ because it obscures tuning. Also, he mentions that choral performance could be the only way to achieve ‘steady intonation’. From Stevens’ reply we learn that he is unaware of the constant nature of the vibrato in his own ensemble’s performances. Stevens also says he feels the use of vibrato is suitable when, as in this case, the music expresses ‘tremendous excitement and tension’ as well as ‘a climax both musical and sexual.’ By employing electronic measurement, he mentions that seven cycles-per-second are acceptable, as is a deviation from pitch of less than ±3% (but does not explain what it is 3% of).

3. Munrow’s views

This particular exchange of letters so intrigued David Munrow that he took them as a starting point for his little-known essay entitled ‘Vibrato’ which is presumed to have been written during 1970 after The Musical Times correspondence was published.29 The essay may be unfinished or perhaps survives only in part, but some drafts of the concluding remarks make it possible to judge the tenor of Munrow’s argument and trace his reasoning backwards into the earlier part of his text. The essay itself is a handwritten document – a page of it on Dartington Summer School headed paper – with several substantial re-workings and corrections, and it is currently held in the special collections at the Royal Academy of Music.
To illustrate his essay, Munrow chose 13 examples of recordings that he felt were representative of vibrato used in different ways, some instrumental and some vocal; it is also possible to compare his comments with the actual sound recordings and to undertake sonic analysis to see if any correlations can be extracted when spectrograms are considered.
Munrow’s opens his essay with a comment on the letters from The Musical Times:
This correspondence is the first really good argument in print about vibrato which I have come across. It illustrates the confusion that exists about the word – exactly what it means, how it is defined and how far it should go.30
He suggests, as a starting point, a simple definition of vibrato as ‘the slight and more or less rapid fluctuation of pitch’31 which we can see has been taken directly from Donnington’s entry in the Grove dictionary already discussed.32 Even though Munrow acknowledges that his definition is not complete, its simplicity still comes as something of a surprise.33 Limiting himself to pitch should strike us as unexpected when, before this, he mentions the two studies by Carl Seashore which discuss how sound waves reveal the complexity of vibrato not just in terms of speed, but also loudness and timbre. That Munrow has not included this information suggests that his intention in this essay may be to explore Roche’s very particular comments about intonation and just pitch vibrato. Another possible reading is that Munrow did not use Seashore’s definitions because he was anxious to explore the common assumption that vibrato is simply a wobbly pitch.
On the back of one of his handwritten pages he notes a few comments from the letters:
A real contrast between resonance and dissonance cannot be given proper consideration with general vibrato. (Roche)
Vibrato [is] used as a means of ornamentation and expression. (Stevens)
On these matters [vibrato] the ear is the ultimate judge. (Roche)
Vibrato is hardly a legitimate means of musical expression at all. (Suckling)34
Each of these comments refers either to tuning (Roche) or to vibrato as expression (Stevens and Suckling). Taking these comments as a key to Munrow’s thinking, each recorded extract from the discography will be considered in terms of vibrato depth and speed, and also the visual nature of the spectrogram information.

4. Method 

Since there is a varied discography to consider it is imperative to choose a method of analysis which is appropriate for each of the recordings so that comparisons can be drawn between them. In order to measure the different vibratos at the same time, spectrographs have been chosen; these are graphs of frequency and intensity over time and can be plotted from any sound-source.
All of the recordings considered from the short discography compiled by Munrow have required digitisation. Where possible, recordings have been sought from commercial re-releases and details of the source are given for each recording in the results section. Where the source has been digitised from an LP using domestic equipment it has been recorded into Audacity software running on Mac OS X.
Short sections of each audio extract have been chosen to include reasonably long and prominent notes where vibrato can be heard most clearly; this way it is possible to read the vibrato shape from spectrogram pictures clearly.35 However, in order to facilitate not only accurate measurement but also comparison between the different spectrogram plots, the sensitivity of the spectrogram has been calibrated to reduce ‘noise’ readings such as surface noise from 78rpm records; this has been done by following suggestions given in the CHARM Tutorial.36 It is important to reiterate that changes to the scales of the graph affect the way it is coloured and sized, not the values of the results themselves and, therefore, are purely for a clarity of screen image.
For example, the following figure is a spectrogram showing an extract from the first record in Munrow’s discography. Jussi Björling is singing the duet Solenne in quest’ ora from Verdi’s La forza del destino, Act III. The spectrogram image is taken from the Sonic Visualiser program.37 This program, like many basic sound-editors, allows the user to view the waveform of the sound signal in various ways. Sonic Visualiser cannot itself edit the sound wave so there is no possibility of the results becoming corrupted by accidental user intervention.
Figure 1
Figure 1: Björling extract
About halfway across the screen we can see a long note is being sung. The harmonic content of this note can clearly be seen in the way that is visible at higher and lower pitches. It is also easy to observe the differing intensity of the note. On the third waveform from the bottom (the one below the green square) we see how the orange colour shows points of maximum volume while the green shows the points of minimum volume.
The green square is a measuring tool. Here it has been placed around five consecutive vibrato cycles so that the time value of cycles per second can be calculated. The same square can also be repositioned to read the amplitude of the waveform to see how wide an individual cycle is.
If the ear is indeed the ultimate judge as Jerome Roche said (and David Munrow quoted), then it ought to be possible to find links between what Munrow’s ear heard, and what judgments he made. Ignorance of the physiology of the singer (such as whether the vibrato was learned or innate, diaphragmatic or laryngeal…), while to the detriment of a thorough investigation will not hinder an exploration of Munrow’s comments since it is fair to work with the assumption that he did not know the exact circumstances of each of the performances in his discography either.

5. Results 

KeyMunrow's recordAuthor's source Vibrato speed on long note (cycles per second) Vibrato depth on long note (cents)
JU Solenne in quest' ora Jussi Björling tenor, Robert Merrill baritone.
RCA CM 9844-E (10")
Jussi Björling: Greatist Hits
iTunes store
JP Duet from Cantata No 42 J.S. Bach
Eileen Farrell Soprano, Jan Peerce Tenor.
RCA LM 6023
Private record collector 6.2249
PM Kyrie from Missa da capella – Monteverdi.
Prague madrigal singers
Supraphon SUA 10558
Transfer from LP 6.1 147
TYT John Barleycorn
The young tradition.
Transatlantic TRA 172
Transatlantic Folk Box Set
iTunes store
 Wedding song
Bulgarian Women.
The living tradition series, ARGO RG562
‘World Music’ has not been sourced for this paper.  
JN ‘Triste Espana’ Janita Noorman & Musica Reservata.
Philips SAL 3697
Transfer from LP12.7 45
JB ‘Triste Espana’ James Bowman & EMC
BBC Broadcast (Plaistow)
This recording is not available. The same track is taken from ‘Music for Ferdinand and Isabella of Spain’ Testament SBT 12517.1111
LT The mad scene Lucia de Lammermor, Donizetti
Luisa Tetrazzini
ATL 4079 Fidelio
Internet download 7.2110
AD Agnus Dei from Mass in B Minor. Alfred Deller. Leonhardt Baroque Ensemble. BachGuild BG 550.LP transfer purchased from 6.7227
CL ‘Please don’t talk about me when I’m gone’ Cleo Laine.
Fontana TL 5 316
Cleo Laine: The Collection
iTunes store
 ‘Llul arique’ The Flute of Latin America – Los Calchakis. Major Minor records SMLP76‘World Music’ has not been sourced for this paper.   
CD Heartsease
Carl Dolmetsch, Joseph Saxby
Decca LM 4518 (10”)
Carl Dolmetsch
Pearl CD transfer.
Gem 0234
HY Air on a G String
Hozan Yamomoto Shakuhachi
Victorola VICS 1458
LP transfer4.4101
 Doina Oltu Hora
Panpipes and Romanian Folk Orchestra
Artia AZp-105
‘World Music’ has not been sourced for this paper.   
 ‘Mevlana’ Mustafa Kandirali
Clarinet and Turkish night club band
‘World Music’ has not been sourced for this paper.   
HS Feathers by Hale Smith
Eric Dolphy saxophone.
ESQ 32. 153
Out There/Eric Dolphy
New Jazz
OJCCD-023-2 (NJ-8252)

Figure 2
Figure 2: speed and depth of vibrato in prominent long notes from the above recordings.

6. Discussion

The graph above shows the plots of vibrato speed and depth for each of the extracts listed in the results table. Taking each example in turn will help to identify some of the key features of these findings.
What can be observed from the example of Jussi Björling’s singing? Vibrato can be heard clearly on every note except one (in the turn before the climax). The oscillations on the long climactic note were extremely regular. This information can be seen clearly on the spectrogram.
Munrow said that this example was ‘a good illustration of the battle between voices and orchestra… [and]… it makes clear that vibrato has become one of the singer’s principal weapons in a formidable armoury.’38 In his essay he made a clear link between vibrato and the process of making enough volume to sing with a large orchestra. Below this recording in his list he wrote: ‘Whatever you may think of this style of singing and its use in romantic opera, it has produced generations of singers who can’t sing in any other way.’39 Since this is the only recording on the list that has a specific location embedded in the essay, we know that he chose to follow it with a quote from Marafioti’s book Caruso’s Method of Voice Production:
A wonderful display of brute force […] performed by ignorant screamers who feel proud of their athletic achievements.40

Firstly let us consider why the vibrato is present in the first place. Munrow suggests that it is a necessary by-product of making a lot of volume, yet he does not elaborate on how or why these two factors are linked. By quoting Marafioti he also implies that he agrees that it has a ‘macho’ element attached (‘brute force…’). Munrow avoids comments about the physics of the sound waves as he would not have been able to without laboratory equipment. However, when it comes to the psychology of hearing, he makes several comments: firstly he suggests an appreciation of the craft of this singing (‘formidable armoury’) and then goes on to imply an alignment of his views with those of Marafioti that it is or could be ‘ignorant’ and ‘athletic’. Finally, Munrow gives us his opinion that these sorts of singers have lost the ability to sing in any other way. This implies that Munrow seeks to criticise every classical singer who uses this vocal technique, but on closer reading he only seeks to highlight the fact that this style of singing often means that artists sing in no other way. In other words, it is the inflexibility of this style that he is bemoaning.
Munrow would have also realised that without the sort of laboratory equipment used in Seashore’s vibrato studies he would have been unable to comment on the exact measurements of vibrato. However, Seashore himself suggests that ‘to prepare for an actual and effective appreciation of the magnitude, the universality, and the complication of the vibrato...’ records can simply be played at slower speeds.41 Munrow may well have followed this advice by simply selecting the 16rpm setting on his turntable rather than the 33 setting. Current software packages can also preserve the pitch of the performance while slowing it down. When this is done it is possible to listen for the changes in timbre during each vibrato cycle.
Let us now observe the cycles on a spectrogram image taken from the Sonic Visualiser programme.
Figure 3
Figure 3: Björling’s spectrogram created by the author
The spectrogram displays the regularity we heard in the vibrato. While we are not measuring the extent of regularity, it is to be noted as a general trend.
As explained in the method, a measuring line has been applied to the image so that the depth of the vibrato (in cents) can be read off, as can the amount of time taken per cycle (in seconds).42 This has been done at the mid-point of long notes where five clear cycles can be observed in each example. Björling’s vibrato on this part of the long note is 6.1 cycles per second and moves through 198 cents.
For his second example, Munrow again chooses a recording of internationally recognised solo singers. For comparative purposes (with Björling), the tenor soloist, Jan Peerce, was measured on an entry 1’9” into the track. His vibrato on that prominent and long note was found to be similarly fast at 6.2 cycles per second but almost half of an equal-temperament semitone wider at 249 cents.
Having taken note of these results, we now turn to next example on Munrow’s list: The Prague Madrigal Singers. Munrow wrote on his list next to this recording: ‘It’s not just solo singing: listen carefully to this choir – exhibiting many other faults besides vibrato.’ He also adds: ‘The lines of polyphony aren’t clear…’ which is a negative reaction to The Prague Madrigal Singers and their use of vibrato. We also note that it is generally dismissive of their performance standards. When he writes: ‘It’s not just solo singing’, Munrow is referring to his previous comments about Jussi Björling’s style of singing and the two soloists singing Bach. This Prague Madrigal Singers example supports Munrow’s observation that ‘it has produced generations of singers who can’t sing in any other way’ because here, as in the Bach, are singers performing music which is clearly not Romantic opera but using the vocal technique one would expect to hear in Verdi’s music, for example. Once again, measurements were taken from a prominent tenor entry, in this case at the return of the Kyrie text.
Contrasted with the choral singing of The Prague Madrigal Singers is this song which Munrow also played in his radio series Music of Ritual: ‘John Barleycorn’, sung by The Young Tradition. The recording sounds unusual because of the acoustic space, or lack thereof – when a spectrogram is examined it is obvious that it has been recorded in an anechoic chamber because there is no reverberation at all. This confuses us as listeners and as a result the voices sound more clearly delineated than they really are. Despite these very clear vocal lines we can observe from the graph plots, there is vibrato here after all. The Young Tradition were at the centre of the folk music revival in 1960s London and had at this time just released their 1969 album ‘Galleries’ which featured David Munrow among other artists. They were typical inclusions to a young person’s record collection at this time and their specialism in unaccompanied singing also extended to medieval music. ‘Galleries’ included a version of the Agincourt Carol.
The next two recordings are both of the same piece of music and follow on in the same section of Munrow’s list from ‘John Barleycorn’. Since these extracts have no specific comments written next to them we might also hear them as if in response to the Prague Madrigal Singers; suggesting that here Munrow thinks the lines are clear. Triste Espana was first sung by Jantina Noorman and then by James Bowman. Noorman was the main singer with Musica Reservata with whom Munrow also played at this time. Michael Morrow who directed this ensemble had particular views about singing which he articulated in Early Music magazine during the 1970s. Much influenced by the ‘world music’ research of A. L. Lloyd at Goldsmiths University, Morrow realised that ‘singers (and their public) through the ages have always maintained that there is only one valid vocal style – their own.’43 He also felt that this was problematic when pursuing ‘authenticity’ because ‘one still needs to insist that for the music of any period an appropriate vocal style is absolutely essential.’ An idea that he found difficult to take into the concert hall because ‘there are two things that most audiences and all music critics abhor: non-conventional singing and non-conventional violin playing.’44 Morrow knew that his route away from what he calls ‘conventional’ singing, i.e., like those heard in the first group of recordings on Munrow’s discography, would be unpopular but he was convinced that it was essential to understanding this music.
In an interview with J. M. Thomson, Morrow revealed that he felt ‘singers […] are disinclined to do anything that is vocally unfamiliar – and, of course, they’re often technically unable to do things that singers of the past learned as part of their basic training.’45 This chimes with his article Musical Performance and Authenticity where Morrow observes that in order to understand and explore past vocal styles one must look beyond current Western music to appreciate the enormous variety of vocal sounds that can be made. He observes that ‘quality need not necessarily spring from a flawless technique – indeed by its conviction it can often override technique altogether.’46
These views would have most certainly been known to Munrow when he compiled this discography on the cusp of the 1970s. Indeed, in a Gramophone Magazine interview in 1974 Munrow says: ‘I think that the vocal music of thaxt time [Shakespearean] needs to be sung in a radically different way from later music. Basically, there was no vibrato.’47 In the second example of Triste Espana, by Munrow’s own ensemble, we hear the voice of countertenor James Bowman. Bowman and Munrow met at a madrigal rehearsal in West London in the 1960s and his voice matches this ‘radically different’ way of singing which has very little noticeable vibrato. In the same interview Munrow described meeting Bowman in 1967 and thinking that ‘here was the most fabulous “noise” I’d ever heard.’48 The contrast between Musica Reservata attempts to reconstruct older singing techniques and Munrow’s success led John Potter to describe Munrow’s ensemble as the first time that ‘early music singing was perceived as attractive to listen to.’49
This recording of James Bowman’s singing is not the exact one that Munrow listed in his paper. When he was writing, the album Music for Ferdinand and Isabella of Spain still lay in the future and Munrow had listed a live BBC broadcast of this piece from Plaistow; a broadcast which appears not to have survived. It is, however, the same singer singing the same piece under the same direction. When these two examples of Triste Espana were compared it was not possible to measure the speed of James Bowman’s vibrato on any notes apart from the last one as that was the only note that had enough clear cycles on it.50 We may also note that Jantina Noorman exhibited a measurable vibrato despite her oscillations being difficult to identify by ear.
These three recordings appear to belong together in the same way as the first three. They represent a minimal vibrato style and vibrant, clear lines of music. However, there now follows a pair of recordings of soloists that Munrow grouped with the same explanation:
Many of the best early opera singers did use vibrato with taste, care and could effect a portamento.51
The Tetrazzini example is of particular interest since she, like Jussi Björling, was famous for her Romantic opera roles. However, in this extract it is clear that she is not limited to singing with the same style as Björling because she uses minimal vibrato to imitate birdsong. Tetrazzini called this her ‘white voice’ and wrote about her decision to sing this way:
Too wide a smile often accompanies what is called ‘the white voice.’ This is a voice production where a head resonance alone is employed […]. This ‘white voice’ should be thoroughly understood and is one of the many shades of tone a singer can use at times, just as the impressionist uses various unusual colours to produce certain atmospheric effects.
For instance, in the mad scene in Lucia the use of the ‘white voice’ suggests the babbling of the mad woman, as the same voice in the last act of Traviata or in the last act of Bohème suggests utter physical exhaustion and the approach of death.
An entire voice production on these colourless lines, however, would always lack the brilliancy and the vitality which inspire enthusiasm.52
So Munrow liked this singing and thought it was in good taste. But his point seems to be not that it was representative of Tetrazzini’s voice but rather that it demonstrated her flexibility as an artist. It shows that she is in control of her vibrato because she can reduce it in her ‘white noise’ passages, which Munrow seems to suggest artists like Björling or the Prague Madrigal Singers cannot as he indicated by his comment: ‘...who can’t sing in any other way.’
Tetrazzini also writes directly about the subject of vibrato:
The pupil suffering from tremolo or even very strong vibrato must have courage to stop at once and to forego having a big voice. After all, the most beautiful voices in the world are not necessarily the biggest voices, and certainly the tremolo is about the worst fault a singer can have. But that, like almost any other vocal defect, can be cured by persistent effort of the right kind.53
Here she suggests that a big voice is a choice after all and we can see that this is one possible place Munrow may have read about a link between vibrato and volume.
Alfred Deller is the second countertenor to feature on this list but his sound is quite distinct from James Bowman’s although we should note that he is singing quite different repertoire and at a higher tessitura than Bowman. Deller’s vibrato is much more obvious towards the ends of the notes where it reaches 227 cents.
Our last vocal example appears in section grouped under a note by Munrow: ‘Use of all kinds of controlled vibrato in jazz and pop worlds’. Cleo Laine is one of the most famous jazz singers of all time. Laine also uses vibrato most noticeably towards the end of her notes.
When all of these vocal vibratos are plotted on the same graph we can draw comparisons between them. Undoubtedly, it is possible to form an opinion simply by ear but even as far back as the 1930s Harold Seashore concluded that ‘the vibrato is not heard even by the best musician as it really is, which lies at the bottom of the confusion which has prevailed on this subject.’54
So with Seashore’s words in mind, it ought not to surprise us that these figures turn out to be rather unexpected.
Figure 4
Figure 4: graph of results for vocal extracts.
One of the first things we can note is that none of these singers completely eliminates vibrato from their voice. That is no great surprise since vibrato is one of the features that enables us recognise a sound as human, a phenomenon which has been described by John Chowning in his study ‘Perceptual Fusion and Auditory Perspective’.55 Even when Luisa Tetrazzini comes close to eliminating vibrato, none of her notes exhibit an utterly unwavering tone. James Bowman, as I mentioned earlier, only produced a single note with more than five clear vibrato cycles but each note did have cycles.56
Whereas the depth of vibrato shows considerable change between each example, there is a far smaller variation between the speeds of the vibrato. Each voice displays a rate between 5.6 and 7.2 cycles per second with only two exceptions, Jantina Noorman (as part of the ensemble Musica Reservata) and The Young Tradition. This would suggest that speed is linked to vocal training since both Noorman and The Young Tradition are using singing techniques that are not normally associated with Western classical music. This ‘folk’ singing sounds as though it has no vibrato present yet the spectrogram records clear cycles.
Is it just vibrato that enables us to identify voices as human? Chowning demonstrates that it is in fact a combination of harmonics and vibrato that make a note sound human to us; harmonics being what make up the timbre of the note; that is all the extra information after the fundamental tone creating shrillness or richness.[57] Timbre can come in cycles too – we can hear that in the very first example of Jussi Björling when it is slowed down, it sounds as if his vowel is changing between the rising and falling parts of each cycle. But are these significant findings if we can’t hear them without technological aid?
In would appear that Munrow got stuck at this point too which may be why he moved away from Seashore’s research and assembled this discography to try to illustrate the way vibrato appears to the listener in different situations. This means that however we choose to analyse data in this particular study, the features that both our ears and spectrograms make quite obvious lies not on this scientific plane at all: a defining feature of vibrato in these examples is when it is used. Not when in the phrase or when in the piece but when in the individual note. And this is what I suggest Munrow was trying to illustrate.
Let us consider two extremes: Jussi Björling uses vibrato fairly uniformly throughout his singing to the point that Denis Stevens’ school of thought is inverted – Björling’s only straight-toned note seems to be for expressive reasons!58 Each note begins instantly with vibrato which continues at an approximately uniform rate all the way through. This can be seen quite clearly with the naked eye on the spectrograph of his singing. However, Cleo Laine – a singer whom Munrow openly admired – does not59. She shares a common trait with both James Bowman and Alfred Deller in that she begins a note with an almost straight-tone and then allows the vibrato to develop during the note. It’s a best-of-both-worlds approach; the pitch stability of a ‘pure note’ and the richness and expression of vibrato. A very obvious example of this can be heard in Triste Espana on the recording by The Early Music Consort of London, in the voice of the tenor, Martyn Hill, who is not measured in this study. Hill’s last note in the first phrase of this track is a clear example of vibrato developing during a note.
It is easy to see this developing vibrato on the spectrograms as the following two examples show:
Figure 5
Figure 5: Spectrogram of Deller’s vibrato developed
Figure 6
Figure 6: Spectrogram of Cleo Laine’s vibrato developed
From the colouring of the spectrogram plot we can also see that the intensity of the waveform is subject to a vibrato where the peak of each vibrato wave is more red than the middle or bottom. This could contribute to the bright sound of Cleo Laine’s voice. In Deller’s example we notice a general swelling of intensity that occurs with the developing vibrato which suggests he uses vibrato as an expressive device.
So what of the final three non-vocal examples, can they provide any clues to help us interpret this discography? Not surprisingly Munrow has chosen an example of recorder playing by Carl Dolmetsch. On first listening Dolmetsch seems to be using an unusually obvious amount of vibrato, much more than in other tracks from the same recording session with Joseph Saxby. It is fair to assume, therefore, that vibrato is an important part of his interpretation of Heartsease. The result when plotted on the graph (CD) is most similar to James Bowman (JB). The vibrato from Carl Dolmetsch is more shallow than James Bowman, so why is it more obvious to the listener?
One possible explanation is that Dolmetsch’s playing is an example of a pressure vibrato where what we hear is a difference in wind-pressure on the recorder to make the oscillating sound. In order to see this clearly the colour rotation has to be increased to 100 on the spectrogram software. This colouring allows us to see how the intensity of the waveform changes constantly through each note with green being the least intense and red the most intense.
Figure 7
Figure 7: Pressure vibrato in the recorder playing of Carl Dolmetsch.
Dolmetsch’s entry in this discography came after a ‘world music’ recording (The flute of Latin America) under which Munrow had written: ‘Quite wrong to suggest that vibrato is a sophisticated device…and that primitive musicians don’t use it.’ This suggests that Munrow was drawing a parallel between vibrato in the Latin American flute and similar vibrato in Dolmetsch’s playing. This would have been to show it is not a purely Western phenomenon. The world-music recordings have not been included in this study.
In the last examples Munrow simply wrote above them on his list ‘Vibrato as an expressive device’ and here we see the most pronounced demonstration of the developed vibrato. Firstly, Bach’s famous Air on a G String played on the Japanese shakuhachi (bamboo flute). Here is the first note of that famous tune taken from the spectrogram plot.  
Figure 8
Figure 8: Air on a G string played on the Japanese shakuhachi.
There is a clear development of the vibrato through the note in this example too and the same phenomenon is observed in much of the shakuhachi playing on this track. We should also note that at a rate of 4.4 cycles per second this is one of the slowest vibratos we have heard so far.
The slowest vibrato, however, is recorded in the last example on Munrow’s list: Feathers by Hale Smith, played on the saxophone by Eric Dolphy. This has a rate as low as 1 cycle per second on certain prominent long notes, and moves through 117 cents. In this spectrogram plot we can see not only is the vibrato prominent and slow but that portamento is also an important part of this performance.
Figure 9

Figure 9: extract from a long note in ‘Feathers’ by Hale Smith (Eric Dolphy, alto sax)

7. Interpreting the results

Taking the information above, we can now consider how Munrow has built his discography. It starts with two groups of three examples. In the first group he played an example of operatic singing as used chiefly in Romantic opera. This was the voice of Jussi Björling. Munrow expressed disappointment that many artists exclusively use this style of singing included a recording of Bach cantata 42 sung in a Romantic style and also The Prague madrigal singers singing Monteverdi in similar Romantic style. Munrow’s point would appear to be that while this is a perfectly legitimate and impressive style of singing it is not suitable for all forms of music, particularly since it only developed once the orchestra got louder i.e. in later operatic repertoire.
Contrasted with this ‘Romantic style’ singing, Munrow’s next section of the list included some music where minimal vibrato was used. Firstly the folk singing of The Young Tradition where the style was bold and clear, and then the voices of Jantina Noorman and James Bowman both singing the same song with minimal vibrato but using very different vocal techniques. This section of the discography seems to demonstrate how much variation there is in a minimal vibrato sound and also how clearly choral and polyphonic textures can be when vibrato is reduced. Munrow also included a track of Bulgarian singing in this section of his discography that might have been intended as drawing a parallel with the research that Michael Morrow (director of Musica Reservata) was undertaking into folk singing as an explanation of Jantina Noorman’s singing style.
The next two extracts show famous solo singers from a Western music tradition singing solo arias with little vibrato. Luisa Tetrazzini and Alfred Deller both sing parts of their arias with minimal vibrato but do allow it to develop on longer notes. This theme is then taken up in the track from Cleo Laine who develops a very wide vibrato on long notes which all start with minimal oscillation suggesting that she uses vibrato consciously rather than automatically. This section highlights how artists can exercise choice and control over their vibrato.
Then Munrow turns to instruments and includes two examples of vibrato on the recorder, one from Latin America (not included) and one by Carl Dolmetsch which is notable for its use of pressure vibrato. And in the last two examples included in this study we find uses of vibrato as an ‘expressive device’ by a Japanese shakuhachi player and a jazz saxophonist. Both of these tracks show vibrato developing on long notes but not being omnipresent on every note. These vibratos were among the slowest measured.
As for the records sourced, we can be reasonably sure that they were from Munrow’s own collection. In an interview he once said: ‘That’s one of the reasons I like doing Pied Piper so much – I use my own records, often rare ones, that aren’t in the BBC library.’60

8. Conclusions

Munrow’s own conclusion in his essay touches on the central idea behind this discography when he quotes extensively from Carl Flesch’s 1924 violin tutor, which suggests that we tire of ‘perpetual vibrating in an excited manner’ [my emphasis], because such an effect makes ‘all performers appear too like one another.’ 61
So, in searching through Munrow’s text, the only completely negative comment he makes about vibrato is when it is used indiscriminately; that is, on every note to a more-or-less unvarying extent and even then only outside the Romantic operatic repertoire. This is heard in the examples of JP and PM. We should note that these examples show no extremes of depth or speed in their vibrato but are united by their constant use of it.
Including The Prague Madrigal Singers in this discography serves an interesting purpose. Not only does it allow Munrow to comment on how unclear the lines of polyphony are when sung with unrelenting vibrato but it also allows him to draw favourable attention to the sound of The Young Tradition, Musica Reservata and his own ensemble, The Early Music Consort of London, all of whom Munrow had performed with before 1970. Munrow may also be suggesting how unavoidable The Prague Madrigal Singers were since they were recording much historically important early repertoire at a time when few other groups were tackling such an area. There was little alternative choice if you wanted to hear the Monteverdi masses or similar early choral repertoire. With this in mind we can assume that a subtle advertisement for the newer early music ensembles (chiefly The Early Music Consort of London) is in operation…
The minimal vibrato sounds that Munrow listed, chiefly TYT, JN, JB and LT, were all faster and shallower than the other examples of vibrato. When this is combined with Munrow’s own explicit disapproval of constant vibrato we begin to understand that he is suggesting a preference for ‘controlled’ vibrato. Such controlled vibrato is heard in the examples of LT and AD where they consciously opt for a minimal vibrato sound even though in different repertoire we may hear them use more vibrato. By ‘controlled’ he refers to vibrato when used as the artists chooses, rather than unrelentingly applied. In the instrumental extracts he also refers to this vibrato as being used for expressive purposes.
Munrow’s discography, therefore, shies away from scientific observation as in the Seashore studies almost 50 years before him, and opts for an observational approach justified by a comment in that catalytic record review by Jerome Roche: ‘MT readers need not be blinded by the science […] for one these matters [vibrato] the ear is, thankfully, the ultimate judge’.62


  • Apel, Willi: ‘Vibrato’ in The Harvard Dictionary of Music. London: Heinemann, 1944.
  • Blythe, Alan: ‘David Munrow Talks to Alan Blythe’ The Gramophone, May 1974 1974.
  • Chowning, John: ‘Perceptual Fusion and Auditory Perspective’ in Music, Cognition, and Computerized Sound, edited by Perry Cook, Cambridge, Massachusetts: The MIT Press, 1999.
  • Caruso, Enrico: Luisa Tetrazzini Caruso and Tetrazzini on the Art of Singing Metropolitan Company, 1909,
  • Cook, Nicholas, & Leech-Wilkinson, Daniel: ‘Charm Tutorial: Techniques for Analysing Recordings: An Introduction’
  • Donington, Robert: The Interpretation of Early Music. London: Faber and Faber, 1963.
  • ——— ‘Vibrato’ in Grove’s Dictionary of Music and Musicians, edited by Eric Blom, 1954.
  • Flesch, Carl: The Art of Violin Playing. Translated by F. H. Martens. Vol. 2. Boston, 1924–30.
  • Leech-Wilkinson, Daniel: ‘The Changing Sound of Music: Approaches to Studying Recorded Musical Performance’ CHARM,
  • Marafioti, P. Mario: Caruso’s Method of Voice Production: the Scientific Culture of the Voice. New York; London: D. Appleton and company, 1922.
  • Metfessel, Milton: ‘The Vibrato in Artistic Voices’ in Studies in the Psychology of Music Iowa: The University Press, Iowa City, 1932.
  • Morrow, Michael: ‘Musical Performance and Authenticity.’ Early Music, 6, no. 2 (1978), 233–46.
  • Morrow, Michael, and J. M. Thomson: ‘Early Music Ensembles 1: Musica Reservata’ Early Music, 4, no. 4 (1976), 515–21.
  • Munrow, David: ‘Dm 9/11: Vibrato’ The Royal Academy of Music Archive, London, 1969/1970.
  • Potter, John Vocal Authority: Singing Style and Ideology. Cambridge: Cambridge University Press, 1998.
  • Roche, Jerome: Review of ‘Monteverdi and His Contemporaries’ The Musical Times, 110, no. 1522 (1969): 1252.
  • ——— ‘Vocal Vibrato’ The Musical Times, 111, no. 1526 (1970): 387–88.
  • Schoen, Max: ‘Pitch and Vibrato in Artistic Singing: An Experimental Study’ The Musical Quarterly, 12, no. 2 (1926): 275–90.
  • Seashore, Carl E.: Psychology of the Vibrato in Voice and Instrument, University of Iowa Studies in the Psychology of Music. Iowa City, Ia.: The University Press, 1936.
  • ——— The Vibrato, Studies in the Psychology of Music V. 1. Iowa City, Ia.: The University, 1932.
  • Stevens, Denis: ‘Vocal Vibrato’ The Musical Times, 111, no. 1526 (1970): 387–88.
  • Suckling, Norman: ‘Vocal Vibrato’ The Musical Times, 111, no. 1528 (1970): 601.

Edward Breen

Edward Breen was a choral scholar at King’s College, London and holds a Master’s degree in Historical Musicology (Goldsmiths College) and a Postgraduate Vocal Diploma (Trinity College of Music). He is currently writing his PhD under the supervision of Professor Daniel Leech-Wilkinson on ‘The performance practice of David Munrow and the Early Music Consort of London’. This year Edward holds an Edison Fellowship at the British Library Sound Archive. As part of his research, Edward is undertaking a series of interviews with musicians from The Early Music Consort of London and Musica Reservata, details of which are available from
For the last ten years Edward worked as a singer and specialized in choral music and oratorio. He has performed with ensembles such as Chapelle du Roi, Kammerkórinn Carmina (Reykjavik), Euterpe Baroque Consort (Antwerp) and The London Festival Orchestra; and with many of London’s professional church choirs including St Paul’s Cathedral and Westminster Abbey. He now teaches at Morley College.
  1. The most obvious example of this is: G. Moens-Haenen, ‘Vibrato’ In Grove Music Online. Oxford Music Online, (accessed March 1, 2010).
  2. Carl E. Seashore, The Vibrato, Studies in the Psychology of Music V. 1 (Iowa City, Ia.: The University, 1932), 344.
  3. Max Schoen, ‘Pitch and Vibrato in Artistic Singing: An Experimental Study’, The Musical Quarterly, 12, no. 2 (1926).
  4. The date, 1921, is supplied in Seashore’s summary when he reviews Schoen’s work: Seashore, The Vibrato, 345.
  5. Ibid., 8.
  6. Ibid.
  7. Ibid., 9.
  8. Ibid., 349.
  9. Robert Donington, ‘Vibrato’ in Grove’s Dictionary of Music and Musicians, ed. Eric Blom (1954), 764.
  10. Milton Metfessel, ‘The Vibrato in Artistic Voices’ in Studies in the Psychology of Music (Iowa: The University Press, Iowa City, 1932).
  11. Ibid., 18.
  12. Ibid., 69.
  13. Ibid., 18.
  14. Ibid., 72.
  15. Ibid., 84.
  16. Carl E. Seashore, Psychology of the Vibrato in Voice and Instrument, University of Iowa Studies in the Psychology of Music (Iowa City, Ia.: The University Press, 1936), 48.
  17. Willi Apel, ‘Vibrato’ in The Harvard Dictionary of Music (London: Heinemann, 1944), 791.
  18. Ibid.
  19. Donington, ‘Vibrato’.
  20. The pages in question are nos. 168 and 169 which also contain some crossings-out and an annotation in Munrow’s hand: David Munrow, ‘Dm 9/11: Vibrato’ (The Royal Academy of Music Archive, London, 1969/1970). Photocopied sheets from: Robert Donington, The Interpretation of Early Music (London: Faber and Faber, 1963).
  21. Carl Flesch, The Art of Violin Playing, trans. F. H. Martens, vol. 2 (Boston, 1924–30). Quoted in Donington, The Interpretation of Early Music, 169.
  22. Donington, ‘Vibrato’, 765.
  23. Jerome Roche, ‘Review: [Monteverdi and His Contemporaries]’, The Musical Times, 110, no. 1522 (1969).
  24. Ibid.
  25. Denis Stevens, ‘Vocal Vibrato’, The Musical Times, 111, no. 1526 (1970).
  26. Ibid.
  27. Jerome Roche, ‘Vocal Vibrato’, The Musical Times, 111, no. 1526 (1970).
  28. Norman Suckling, ‘Vocal Vibrato’, The Musical Times, 111, no. 1528 (1970).
  29. This date is suggested by the RAM catalogue.
  30. Munrow, ‘Dm 9/11: Vibrato’.
  31. Ibid.
  32. Donington, ‘Vibrato‘.
  33. Munrow’s actual words: ‘if we accept for the moment the fairly simple definition of vibrato as…’ Munrow, ‘Dm 9/11: Vibrato‘.
  34. Ibid.
  35. By ‘long’ I mean a note which is long within the context of the piece.
  36. Daniel Leech-Wilkinson and Nicholas Cook, ‘Charm Tutorial – Techniques for Analysing Recordings: An Introduction’
  37. Sonic Visualiser is Free Software, distributed under the GNU General Public License (v2 or later) and available for Linux, OS/X, and Windows. It was developed at the Centre for Digital Music at Queen Mary, University of London This particular spectrogram plots (among other things) the pitch of a sound (in cents) against time; and in the example shown here the notes sung by Jussi Björling show not only their fundamental tone but also their partials (harmonics) too. For an explanation of measuring vibrato from spectrograms using Sonic Visualiser readers are referred to: Daniel Leech-Wilkinson, ‘The Changing Sound of Music: Approaches to Studying Recorded Musical Performance’ CHARM, Chapter 8, Paragraphs 72–77.
  38. Munrow, ‘Dm 9/11: Vibrato‘.
  39. Ibid.
  40. P. Mario Marafioti, Caruso’s Method of Voice Production: the Scientific Culture of the Voice (New York ; London: D. Appleton and company, 1922), 35.
  41. Seashore, Psychology of the Vibrato in Voice and Instrument, 11.
  42. Please note that in the Sonic Visualiser software programme, this measuring device is locked into the image on screen so that any spectrogram can be viewed at any magnification level without affecting the measurements from this ruler. In this case I enlarged the image significantly in order to set the measuring tool at the peak and trough of the waveform as accurately as the naked eye would allow.
  43. Michael Morrow, ‘Musical Performance and Authenticity’, Early Music, 6, no. 2 (1978), 237.
  44. Ibid.
  45. Michael Morrow and J. M. Thomson, ‘Early Music Ensembles 1: Musica Reservata’, Early Music, 4, no. 4 (1976), 515.
  46. Morrow, ‘Musical Performance and Authenticity’, 241.
  47. Alan Blythe, ‘David Munrow Talks to Alan Blythe’, The Gramophone, May 1974 1974, 2010.
  48. Ibid., 2009.
  49. John Potter, Vocal Authority: Singing Style and Ideology (Cambridge: Cambridge University Press, 1998), 115.
  50. 5 clear cycles of vibrato were taken as the standard measurement for vibrato speed throughout this paper.
  51. Munrow, ‘Dm 9/11: Vibrato‘.
  52. Luisa Tetrazzini Enrico Caruso, ‘Caruso and Tetrazzini on the Art of Singing’. Metropolitan Company, 1909,
  53. Ibid.
  54. Seashore, The Vibrato, 10.
  55. John Chowning, ‘Perceptual Fusion and Auditory Perspective’, in Music, Cognition, and Computerized Sound, ed. Perry Cook (Cambridge, Massachusetts: The MIT Press, 1999), 265.
  56. Due to their scarcity, these cycles could be what John Chowning refers to as ‘jitter’ however, but they have been included because he also explains, ‘The auditory system […] is able to detect a variation in period of a small fraction of a percent.’ Ibid., 236–64.
  57. Readers are pointed in particular to section 20.2.3 ‘Source Identification’ and the corresponding audio example on the compact disc that accompanies the book. In the example Chowning creates a G-pitched sinusoid, then adds harmonics and finally a regular vibrato. The human characteristics of the sound with vibrato can be heard clearly. Ibid.
  58. I refer readers here to Stevens’ remark quoted earlier that the singers in his madrigal recording only used vibrato for the embellishment of key moments.
  59. Munrow mentions his admiration for both Cleo Laine and Alfred Deller in an interview for Gramophone Magazine. Blythe, ‘David Munrow Talks to Alan Blythe‘.
  60. Ibid., 2009.
  61. Flesch, The Art of Violin Playing. Quoted in Munrow, ‘Dm 9/11: Vibrato‘.
  62. Roche, ‘Vocal Vibrato‘.

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