OPTISOUNDWOOD project: enhancing poplar plywood with sound

1CEWPPW2 – September 8th-10th, León, Spain

León, September 8th-10th 2016

OPTISOUNDWOOD project: enhancing poplarplywood with sound absorption properties

Francesco Negro, Corrado Cremonini, Gaetano Castro, Marco

Fringuellino, Antonio Spinelli, Guido Callegari, Roberto Zanuttini


Perforated panels

Acoustic frames

Bass traps

Helmholtz resonance Membrane resonance

Development of sound absorbing wood-based products

Project outline

OPTISOUNDWOOD


Index

INTRODUCTION

• Acoustics of closed spaces

• Helmholtz and membrane resonance

• Wood-based acoustic products

• Why Poplar?

EXPERIMENTAL AND RESULTS

• Perforated panels and frames

• Cylindrical and cubic bass traps

• Acoustic testing

• Acoustic performance

FINISHED PRODUCTS

• Drilling, Finishing, Assembly and Installation

CONCLUSION


Acoustics of large closed spaces

Intended for speech:

• commercial centres

• offices

• dining rooms

• conference halls

Example of noise spectra produced in an office with 24 workers: within

office hours; � during lunch time

Introduction


Acoustics of closed spaces intended for speech

A

VRT

161.0

60=

Reverberation: the persistence of sound due to the reflection of the

sound waves on the surfaces of the room.

Cocktail party effect: talkers are induced to raise their voice.

Ideal reverberation time

depends on volume and use

of the environmentV is the volume of the room, in m3; A is the

total absorption of the room, in sabines.

Introduction


Introduction

Perforated wood-based panels

Walls or ceilings coveringsSeveral variables: materials,

drilling percentage etc.


Helmholtz resonance

Introduction

neck

cavity


Helmholtz resonance

Introduction


Helmholtz resonance

Introduction


Helmholtz resonance

Introduction


Helmholtz resonance

Introduction


neck

air

cavity

Helmholtz resonance

Perforated panel wall

Helmholtz resonator

Introduction


Introduction

Acoustics of recording studios or home theatres

Installation on corners, walls or ceilingsSeveral variables: materials,

drilling percentage etc.


Introduction

Membrane resonance

membrane

air volume

panel surface at the back


Introduction

Membrane resonance


Poplar plywood

Perforated panels

Acoustic frames

Bass traps

Helmholtz resonance Membrane resonance

Development of sound absorbing wood-based products

OPTISOUNDWOOD


poplar

PlywoodPlywood

68%

90 % in 3-5 layers plywood only90 % in 3-5 layers plywood only

Why Poplar?

Introduction

• remarkable lightness to produce light and easy to install elements;

• low density can also be exploited for realizing vibrating elements;

• it is suitable for realizing bendable plywood;

• its light color is suitable for several finishing types;

• it is the only local species able to meet the national industrial needs.


Trends in Poplar cultivation in Italy

ECOPIOPPOGuidelines for sustainable cultivation of poplar: reduction ofchemical products and of farming operations.

EN

VIR

ON

ME

NTA

LS

US

TA

INA

BIL

ITY

• reduction of environmental impact

• accurate planning

• staff training

• workplace safety

SHARED FEATUES

Introduction

• FSC is more demanding (native

vegetation, clone differentiation…)

• PEFC pays more attention to

traditional practices

DIFFERENCIES

• new forms of association

• clone differentiation

• double Chain of Custody (CoC)

FEEDBACKS


Introduction

Trends in Poplar cultivation in ItalyN

EW

CL

ON

ES

MSA clones (higher environmental sustainability)

• good resistance to deseases• fewer treatments• better mechanical properties• funding provided for MSA


Introduction

PO

LY

CY

CL

ICP

LA

NTA

TIO

NS


• reduction of single-species risks

• better trunk conformation

• income at an early stage of the overrall rotation


Introduction


ENVIRONMENTAL

SUSTAINABILITYNEW CLONES

POLYCYCLIC

PLANTATIONS

Wood obtained from the above “non-conventional” plantations is slightly heavier andthe derived material is generally lesshomogeneous, since various clones are used.

It is important to find different uses.


Physicalmodel

Kundt’s tubeReal

application

Reverberationroom

Acoustic testing outline

Experimental

Physicalmodel

Realapplication

Reverberationroom

Panels and frames

Bass traps

Theoretical or small scale specimens Samples in end-use dimensions


Testing on small scale specimens (EN 10534-2)

Experimental – Panels and frames

0.90

0.83

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

64

12

017

623

228

834

440

045

651

256

862

468

073

679

284

890

496

010

16

10

72

11

28

11

84

12

40

12

96

13

52

14

08

14

64

15

20

15

76

α

Hz

1.41%, holes 3 mm

1.41%, holes 5 mm


Experimental

Production of samples in end-use dimensions

Perforated panels

Acoustic frames


Experimental

Production of samples in end-use dimensions

Cylindrical bass traps

Cubic bass traps


Experimental

Reverberation room

EN 354:2003 Acoustics. Measurement of sound

absorption in a reverberation room.


Experimental

Dining room

EN 3382-1,2,3:2012 Acoustics -

Measurement of room acoustic parameters.


00.10.20.30.40.50.60.70.80.9

1

10

0

12

5

16

0

20

0

25

0

31

5

40

0

50

0

63

0

80

0

10

00

12

50

16

00

20

00

25

00

31

50

40

00

50

00

α

Hz

Results

0.000.100.200.300.400.500.600.700.800.901.00

10

0

12

5

16

0

20

0

25

0

31

5

40

0

50

0

63

0

80

0

10

00

12

50

16

00

20

00

25

00

31

50

40

00

50

00

α

Hz

0.000.100.200.300.400.500.600.700.800.901.00

10

0

12

5

16

0

20

0

25

0

31

5

40

0

50

0

63

0

80

0

10

00

12

50

16

00

20

00

25

00

31

50

40

00

50

00

α

Hz

0.000.100.200.300.400.500.600.700.800.901.00

40

50

63

80

10

012

516

020

025

031

540

050

063

080

010

00

12

50

16

00

20

00

25

00

31

50

40

00

50

00

α

Hz

Sound absorbing panel Sound absorbing frame

Cylindrical bass trap Cubic bass trap


Final products

Decorative milling Printing

InstallationAssembly

Drilling, surface finishing, assembly and installation

Painting


Final products

Sound absorbing panels and frames

Basstraps


Conclusions

The OPTISOUNDWOOD project enabled to develop, test and realize

at industrial level new panels and composites.

The project constituted an opportunity of collaboration among

different subjects operating in the poplar chain.

The developed products enable to differentiate the production

of the manufacturer.

The results obtained confirmed the interesting performance

of the prototypes.

Poplar plywood turned out to be adequate for realizing

the designed products.

The availability of poplar timber of local provenance was relevant

to meet the demand of raw material.


Documents

OPTISOUNDWOOD project: enhancing poplar plywood with sound