JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 39

The sound of composite violins investigated

liked when played by the second
player. Listeners' evaluations can be
influenced by the performer's way
of playing the instrument. In our
evaluation experiment, this violin's
sound color was described as harsh.
This is less clear in our selection experiment, as the nature of this experiment emphasizes the positive
qualities of each instrument.
UDC, with a higher anisotropy
than TwillCA and TwillCB, was described as round and soft and was
chosen less as powerful. This could
be an indicator that for composite
materials, a higher degree of anisotropy results in an instrument with a
round and soft tonal color preferred
by many listeners, but with a less
powerful sound. More research is
definitely needed to investigate this
aspect and correlate it with numerical predictions.
In our evaluation experiment, two
violins were preferred more than
others. One had a soundboard from
a laminate of unidirectional and
woven carbon (TwillCB), the other
was made from unidirectional flax
(UDFlax). Although UDFlax had
the least powerful sound among our
prototypes, its sound color being
described as warm, soft and round
still made it a favorite for many listeners. The other favorite instrument TwillCB had a sound color
described as warm and rich. In our
selection experiment, TwillCB was
favored over UDFlax by the listeners with both players. The listener's
preference in our experiments seem
mostly guided by sound color, and
less by projection or loudness of the
instruments. However, when both
instruments have a favorable sound
color, the instrument with the better
projection was favored between the
two most preferred violins. In both
experiments, listeners indicated to
find a warm sound an important
quality parameter, followed by adjectives such as clear, open, round

Fig. 7: Percentage distribution on the description
of the favored sound color
for each of the violins

and rich.
The instruments presented in this
study differ from a classic violin
in a number of ways, therefore we
cannot directly extrapolate the results from our violin with a spruce
soundboard to that of wooden violins in general. We can only say that
between our prototypes, the violin
with a spruce soundboard was not
favored over the full-composite
violins and did not stand out in a
particular way with regard to tonal
color or projection. Future research
has to be performed in order to allow for more direct comparisons between instruments with composite
top plates and truly conventional,
wooden violins.
An alternative road future studies
and artists could take is to investigate the full-composite instruments
as a class of sound-generators of
their own, with their own sonic
possibilities, and be less concerned
about a comparison with their conventional counterparts.
Conclusion
Contrary to popular opinion among
violin players, there is no specific
sound property or quality that we
can assign to the material group of
fiber reinforced composites. As a
consequence no generalizations like
'the sound of carbon violins lack
warmth' hold in our experiments.
Composite materials allow to create violins with a large diversity in
sounds and therefore offer possibilities to change the sound to the

criteria of the player. In theory, by
only varying the material and layup of the soundboard, the sound
of a violin could be changed to fit
the requirements of the player. Our
results follow the logic that soundboards which are more lightweight
and have a lower anisotropy are
more efficient sound radiators than
heavier soundboards with a higher
anisotropy.
Although all our participants can
be considered experienced listeners, individuals prefer different violin-like sounds.
Depending on which violin player is
playing, the preference of the listener can shift between instruments.
Although the sound of some violins
was favored more than others, there
was no such thing as the 'best' violin
sound overall.
This research provides insight in
how violins with soundboards from
different composites can sound, the
possible advantages these materials
can offer in relation to the sound
they produce as a soundboard for
violins, and which of these violins
were favored by listeners. However,
composite materials offer a great
diversity of fibers, polymer matrix
and core materials that must still be
examined. While the craftsmanship
of making good wooden violins has
evolved over centuries, resulting in
an optimization of the realization of
the material's potential. Composite
instruments are very new and may
require a new kind of craftsmanship

SPECIAL ISSUE Sports, Health & Leisure / November 2020 /

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JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020

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