JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 35

The sound of composite violins investigated

Tab.1: Weight of the finished soundboards, engineering constants calculated using eLamX² and estimation of damping of the materials.
The damping is an approximation in comparison to spruce, which was given the 0 value as the benchmark material.

Soundboard

Weight (g)

D11 (Nmm)

D22 (Nmm)

D66 (Nmm)

Damping

Spruce

74.8

15.8

1.1

1.5

0

UDFlax

100.3

14.7

0.9

1.2

0/+

UDC

72

14.7

0.9

0.6

-

TwillCA

71

15.5

6.4

0.7

-

TwillCB

74.8

15.5

6.4

0.7

-

Sandwich

42.3

15.7

15.7

0.7

-

was added as a reference material
(Figure 1):
-	 UDFlax: unidirectional flax fiber
reinforced polymer.
-	 UDC: unidirectional carbon fiber reinforced polymer.
-	 TwillC: laminate of twill woven
and unidirectional carbon fiber
reinforced polymer.
-	 Sandwich: sandwich structure
consisting of CFRP skin and an
aramid honeycomb core.
-	 Spruce: Picea Abies.
The TwillC violin was produced
twice (TwillCA and TwillCB) to
check the consistency of the influence of the material and production
methods on the sound of the violin.
The bending stiffness of a plate is
thought to be crucial to the sound
of a wooden instrument [10], therefore it is taken as a guide to make
these novel composite violins.
Soundboards of old conventional
violins deform most often along the
axis of the instrument [11]. As composite materials offer a variety in anisotropy, the bending stiffness along
the axis of the instrument (D11)
was chosen as the primary design
criteria.
Weight of the soundboards, calculated bending stiffness's D11 (along
the axis/longitudinal), D22 (transversal/radial), D66 (shear) and approximate damping of the materials
are provided in Table I. The plate
rigidities show the variety in anisotropy between the materials.

Tab.2: Strong and weak evidence to reject the null-hypothesis and
link adjectives to the sound of each of the seven investigated violins.

Strong evidence (p-value<0.05)

Weak evidence (p-value<0.1)

TwillCA(1)

dim

loud, closed, bad

TwillCB

warm, clear, loud, good,
powerful, rich

open, round, bright

Sandwich

loud, harsh, nasal, powerful

sharp, rich, bright

UDFlax

warm, soft, round

dull, quiet, closed,
good, weak, rich

TwillCA(2)

loud, sharp, powerful

warm, clear, good, nasal, bright

Spruce

loud, powerful, rich, bright

harsh, good

UDC

warm, soft, good, round

bright

The evaluation experiment
Methodology
Experienced listeners with relevant
musical experience were invited to
take part in the experiment.
The group of participants included
(student) instrument makers, musicians, music teachers and composers.
In the first listening test the members of the audience, rated the six
violins individually on a number
of attributes. This method was
chosen as it is a common way to
judge instruments or musicians in
competitions.
One after another, with approximately 25-30 seconds in between,
each violin was played and the audience was asked to rate the same
set of pairs of adjectives for each
violin and were asked about their
overall preference.
During the entire evaluation experiment, the violinist was positioned on stage approximately

1m behind a lightweight polyester
fabric screen. The violin player was
blinded with a sleeping mask and
the scent of the instruments was
covered with a perfume.
The musician played a musical
fragment of her own choice (88
seconds) to evaluate the violins.
Results
First, we examined how the participants described the sound of each
violin, based on presented pairs of
opposite adjectives.
The null-hypothesis (H0) was that
the audience did not favor one adjective over the other in a pair in
order to describe the sound of a
violin. Strong and weak evidence
to reject this null-hypothesis was
found for each of the presented violins in a number of cases (Table
II). Through this method, adjectives could be objectively linked to
the sound of the instruments.
To investigate how reliable these

SPECIAL ISSUE Sports, Health & Leisure / November 2020 /

jec composites magazine

35



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

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020

Cover
Edito
Contents
TRENDS
Business - Sports and health: a wealth of opportunities for composites
e-Bike - Uncertainties over Chinese supply chains put pressure on electric bike producers
Opportunities - The Gaming industry asks composites players: are you ready?
PROCESSING
Characterization - Bamboo versus maple from a skateboard manufacturer’s viewpoint
Engineering lntegrated loop technology provides new high strength joints for carbon fibre composites
Additive manufacturing - Disrupting the composite tooling supply chain
Biocomposites - Changing the outdoor hardware industry
APPLICATION
Climbing - A mountain in the middle of the city
Acoustic - The sound of composite violins investigated
Loudspeakers - Best sound in the world
Jewellery - Shine bright like a composite
Travel - Carbon fibre composites give luggage a leg up
Watersports - Closed-loop recycling of epoxy composites
Running shoes - Composites make their own mark in China
Sprinting shoes - Future of sprinting: spikeless CFRTP sprinting shoe
Medical - Advanced composite materials for prosthetic sockets in developing countries
Prostheses - A new way to make prostheses and orthoses
Paralympics - ‘‘The company’s objective is to design a future full of choices”
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Cover
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 2
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Edito
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 4
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 5
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Contents
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Business - Sports and health: a wealth of opportunities for composites
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 8
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 9
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 10
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - e-Bike - Uncertainties over Chinese supply chains put pressure on electric bike producers
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 12
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 13
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Opportunities - The Gaming industry asks composites players: are you ready?
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 15
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 16
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 17
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 18
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 19
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 20
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Characterization - Bamboo versus maple from a skateboard manufacturer’s viewpoint
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 22
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Engineering lntegrated loop technology provides new high strength joints for carbon fibre composites
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 24
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 25
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 26
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Additive manufacturing - Disrupting the composite tooling supply chain
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 28
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 29
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Biocomposites - Changing the outdoor hardware industry
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 31
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Climbing - A mountain in the middle of the city
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 33
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Acoustic - The sound of composite violins investigated
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 35
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 36
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 37
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 38
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 39
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 40
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Loudspeakers - Best sound in the world
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 42
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Jewellery - Shine bright like a composite
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 44
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Travel - Carbon fibre composites give luggage a leg up
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 46
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Watersports - Closed-loop recycling of epoxy composites
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 48
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 49
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Running shoes - Composites make their own mark in China
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 51
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Sprinting shoes - Future of sprinting: spikeless CFRTP sprinting shoe
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 53
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 54
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Medical - Advanced composite materials for prosthetic sockets in developing countries
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 56
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 57
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 58
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 59
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 60
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 61
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Prostheses - A new way to make prostheses and orthoses
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 63
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - Paralympics - ‘‘The company’s objective is to design a future full of choices”
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 65
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 66
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 67
JEC COMPOSITES MAGAZINE - Special Issue Composites for Sports, Health & Leisure - November 2020 - 68
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