Q: When you set up this experiment, what were you trying to
prove/discover?
A: After working with Kenneth Bozeman at a Nebraska
NATS workshop where he discussed what he calls, "Practical Vocal
Acoustics", I had the idea that perhaps Britten was using some of the
principles that Bozeman was discussing in the workshop and in his book, Practical Vocal Acoustics. So,
what we were looking to discover was whether or not Britten set the text in
such a way as to exploit “passive vowel modification” strategies resulting in a
timbre that would coincided with the dynamic making, thus making the music
vocally and expressively easier for the singer. Passive vowel
modification differs from Active Vowel modification in that passive vowel
modification results from a change of pitch resulting in a harmonic/formant
interaction without a change of vowel shape, where active vowel modification is
when there is a change in vowel shape so as to create a harmonic/formant
interaction regardless of pitch. The main difference is that the singer
has to "actively" change or modify their vowel as opposed to
"passively" letting the vowel modify as a result of the pitch. In the
end it is a matter of whether you move the pitch (passive vowel modification)
or move the formant (active vowel modification).
Q: What made you choose Benjamin Britten as the example?
A: Both Matthew and I are tenors, and we both have a fondness for
Britten and his music. One of the reasons we love Britten so much is that
we find it to be so easy to sing from a vocal standpoint, and so easy to sing
expressively. Knowing that he was very particular about how he composed his
vocal works, and that he composed them with specific individuals in mind, we
thought he was a natural choice to explore the relationship between the timbres
resulting from passive vowel modification and dynamics.
Q: How can we use physics to prove this?
A: Physics doesn’t necessarily “prove” anything, but
it does help us explain what we observe.
What we now know is that for "covering" to occur the second harmonic
(H2 or 2F0) has to rise above the first vowel formant (F1) or F1 has to be
lowered below H2 usually by lengthening the vocal tract which can occur from
depressing the larynx, puckering the lips, changing a vowel shape, etc.
This passing of the H2 through F1 is what Bozeman calls "Closed"
Timbre. So, using [a], which has a F1 at approximately G5 (middle C is C4), as
an example, if one were to sing a tenor "high A" or A4 on an [a]
vowel one would only need to maintain the [a] vowel shape to achieve "cover",
the crossing of H2 (A5) above F1 (G5). If one wanted to actively modify
by puckering slightly, this would then shift F1 to a lower pitch, perhaps (E5
or F5) and increase the "Closed" or "Covered" quality of the
sound. If F1 is continually lowered to where it is just above or in tune with
H1, the fundamental, then a new quality takes over, what Bozeman calls
“Whoop”. “Whoop” is a very fluty, light
quality that is often associated with soft dynamics or falsetto sounds. In contrast to “Whoop” is a quality Bozeman
calls “Yell” which occurs when F1 is tuned to H2, and as its name suggests is
associated with aggressive and loud dynamics.
The last timbre that Bozeman labels is “Open” which also has an
association with loud dynamics, and occurs when F1 is above H2. Now these qualities can be associated with
different laryngeal modes, for example, Mode 1 is associate with “Open”,
“Close”, and “Yell” timbres, where Mode 2 is associate with “Whoop”. Looking at the research of Fabiani and
Friberg, their study looked at the influence of pitch, loudness, and timbre on
instrument dynamics. They report that
dynamics can even be recognized if the loudness (not intensity) is the same,
therefore loudness can only partially explain dynamic recognition. They argue
that timbre is that missing factor. So, if you put these pieces together then,
you have timbres that coincide with dynamics via established vocal registers or
modes. Using the F1/H2 interaction, you
can then predict what the likely resulting timbre or vocal register/mode is
based on the vowel and pitch, and therefore, the likely resulting dynamic. If the predicted dynamic matches the dynamic
indicated by Britten, then the expressiveness of the singing would be more
naturally and easily accomplished. Furthermore,
if the timbre, dynamic, and pitch corresponded with the most conducive vocal
register or mode, it would also be vocally easier to sing.
Q: How did you set the parameters?
A: For the timbre prediction we used Kenneth
Bozeman’s book, Practical Vocal Acoustics. To determine the vowels for the text we used
an online IPA generator set to American English. We did this because Received British English
tended to favor more mixed vowels and not the purer, if you can call American
vowels pure, American vowels. For
example, the word “blow” in American English is [bloʊ] but in British English is [bləʊ]. We confirmed this by listening to British
tenors who were well-known for their interpretation of Britten’s music. When the transcription software didn’t produce
a transcription, we looked up the word in the Oxford English Dictionary. Following standard classical diction rules,
i.e. Madeleine Marshall’s Singer’s Manual
of English Diction, vowel and “r” combinations were all muted, i.e. changed
to [ə]. For the formant pitches we adapted Scott
McCoy’s suggested pitches in conjunction with Lindsey’s combination of Well’s
and Jones’ vowel chart. To determine
when one timbre was truly different from another, we looked at research about
pitch perception and harmonics. We determined that a plus or minus of a major 2nd
was sufficient to properly identify a timbre.
For example, if F1 was C5, then if H2 was between Bb4 and D5, we would
conclude that H2 was tuned to F1 resulting in “Yell” timbre. Finally, we
associated the timbres with dynamics using established descriptors for the
vocal registers, and dynamics shaping was approximated by increasing or
decreasing the dynamic level one level, i.e. p to mp, every two
beats. The predicted dynamic shaping was
compared to a recording of a well-known tenor and mirrored the tenor’s dynamic
shaping quite well.
Q: How can you tell whether the vowels and the pitches are a
good match?
A: We assigned various dynamics to the timbres, so pp-p was “Whoop”, mp-f was “Closed”, f-ff
was “Open” and f-fff was “Yell”. Then if the predicted timbre matched the
marked dynamic, it was a good match. For
example, if the dynamic was forte,
then “Closed”, “Open” or “Yell” were considered to be a good match. Then, if
the timbre was used in what would be considered an appropriate pitch range, so
for a tenor one would expect “Closed” around G4 or higher, that further
strengthened the match. We also looked at groups of dynamics/timbres, meaning
how often was “Whoop” used correctly with soft dynamics or incorrectly with
loud dynamics. What we are doing now is looking a little more carefully at when
there wasn’t a good match or when the dynamic isn’t used correctly with the
timbre to see if there is a reason why Britten may have chosen to mismatch the
timbre and dynamic. At the moment it
looks like this mismatch is occurring to aid projection.
Q: What was the upshot of the experiment?
A: What we found was that overall, the predicted timbre matched
Britten’s dynamic only 25% of the time.
There were occasions, however, when the predicted timbre matched the
dynamic as much as 50%, but it depended on the individual song. Furthermore, we found that Britten often
assigned the “correct” vocal register or mode for the dynamic when in the upper
portion of the voice. We also looked at
occasions when F2 happened to correspond to H3 or H4. The supplemental amplification of F2 is a
common technique for tenors, and has the effect of aiding diction clarity. We found the F2 supplemental tuning was
occurring over 37% of the time. It was
also frequently being used in the upper portion of the voice and when the
dynamic was soft in conjunction with louder timbres which we interpret as being
Britten’s attempt to aid the singer in projection at soft dynamic levels. Finally, we noticed that when the predicted
timbre and dynamic did not match, the timbre shifts mirrored the dynamic
shifts, i.e. a shift from “Closed” to “Open” would correspond to a dynamic
change of p to mp, etc., as if Britten were cueing the singer as to how a line
should be shaped.
Q: How is this useful for singers? Should it change their
approach to the text/performance?
A: The big take away for singers here
is that with Britten, if you just sing the pitch and the vowel he asks, you
will likely sing the dynamic or dynamic shaping he wants. In other words, Britten has programmed by his
choice of pitch and vowel, how to sing his music. We think this type of analysis would be
beneficial to singers, at least on a macro level. Both of us teach singing, and we frequently
see singers making their lives more difficult by imposing an interpretation on
a piece. If they would just take a
moment and consider what might happen if they just sing what is on the page,
they may find that they don’t need to work as hard to provide a musically
pleasing product. Of course, this is not
always true, but it would seem logical, at the very least, to begin from that
point of view. We think this type of
analysis also has a tremendous impact on the practice of transposing art songs,
particularly. It has become very popular for women to sing song repertoire that
was originally composed for men and vice versa. If you have a composer, like
Britten, who was very specific about what colors or timbres they wanted from
the singer and was also adept at building that into their composition,
transposing them or simply singing them up or down an octave would destroy the
composer’s artistic concept, not to mention making it very difficult vocally to
sing the music. For example, in
Britten’s “Nocturne” from Serenade,
he has very carefully chosen his pitch/vowel/dynamic combinations, a 50% match
and 64% match above C4. To have that piece
sung by soprano an octave higher would completely destroy those combinations
resulting in either the soprano not accomplishing what Britten has asked for or
accomplishing it with great difficulty and vocal manipulation. It is really
wise to do that? With some composers, who are less intentional and adept, this may not be an issue, but it is important
to consider. So, we would say that this
analysis definitely is useful in aiding interpretation, and vital when
considering singing repertoire in transposition.
**********
In case we needed another reminder that singing the text and the proper vowels is important, here we have it!
--Ellen
