The acoustic characterization of porous mediaand its standards

ISO 9053 (resistivity, under revision)

ISO 9237 (Textiles -- Determination of the permeability of fabrics to air)

ISO 4590 (porosity, not always convenient for acoustical porous media)

ISO 10534-2 (normal surface impedance, revision scheduled)

ISO 6721 series (elastic moduli)

ISO 18437-5 (Poisson's ratio[s])

L. Jaouen, F.-X. Bécot, F. Chevillotte

with acknowledgements toP. Bonfiglio & K. Horoshenkov

Details

Do we need [to improve] standards ?

2

Do we need [to improve] standards ?Case of a benchmark involving 7 laboratories (same samples of materials)

1000 2000 3000 4000 5000 60000

0.2

0.4

0.6

0.8

1

Frequency (Hz)

Sound absorption coefficient (normal incidence)

Melamine foam (open pores)

Measurements in impedance tubes following ISO 10534-23

Do we need [to improve] standards ?Case of a benchmark involving 7 laboratories (same samples of materials)

1000 2000 3000 4000 5000 60000

0.2

0.4

0.6

0.8

1

Frequency (Hz)

Sound absorption coefficient (normal incidence)

Coustone(granular)

Measurements in impedance tubes following ISO 10534-24

Do we need [to improve] standards ?Case of a benchmark involving 7 laboratories (same samples of materials)

1000 2000 3000 4000 5000 60000

0.2

0.4

0.6

0.8

1

Frequency (Hz)

Sound absorption coefficient (normal incidence)

Armasound(semi-closed pores)

Measurements in impedance tubes following ISO 10534-25

Do we need [to improve] standards ?Case of a benchmark involving 6 laboratories (same samples of materials)

10 000

15 000

5 000

0

Melamine foam(open pores)

Static air­flow resistivity

10 900± 700

11 000± 500

16 400± 200

9 700± 400

8 800± 500

10 400± 500

Measurements following ISO 9053(mostly without strict conformity to the standard)

6

Do we need [to improve] standards ?Case of a benchmark involving 6 laboratories (same samples of materials)

10 000

0

Static air­flow resistivity

40 500± 5 100

15 900± 100

20 000

30 000

40 000

50 000

Coustone(granular)

47 100± 5 100

25 800± 4 700

26 400± 3 300

41 200± 5 900

Measurements following ISO 9053(mostly without strict conformity to the standard)

7

Do we need [to improve] standards ?Case of a benchmark involving 6 laboratories (same samples of materials)

Static air­flow resistivity

210 000± 46 700

133 300± 13 100

50 000

Armasound(semi­closed pores)

205 700± 11 000

115 300± 16 400

274 200± 65 400

254 500± 56 000

0

150 000

100 000

250 000

300 000

200 000

Measurements following ISO 9053(mostly without strict conformity to the standard)

8

Do we need [to improve] standards ?Obvioulsy: yes concerning ISO 9053.

9

Currently:Diameter (edge) of the samples ≥ 95 (90) mm (leakage may be negligible if ratio area / perimeter is largebut a leakage is a leakage and we test permeable materials ! )

Proposition:Diameter depending on Representative Elementary Volume,examples :29 mm minimum for a foam with small pores95 mm for a granular road pavement.

Some propositions for ISO 9053 revision(Static-air flow resistivity measurement)

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Details

Currently:Superimposed samples with small thickness up to a max of 5

Observation & proposition:Obviously it cannot be applied to all morphologies.(Add an informative note about the estimation using an impedance tubefor perforated plates, woven / non-woven screens and other facings)

Some propositions for ISO 9053 revision(Static-air flow resistivity measurement)

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Details

Proposition:Addition of 3- & 4- microphones methods (as in ASTM E2611)(Explaining what one can do and what one cannot do we willprevent diffuse field computations from TL measurements in tube)

 

Proposition:Addition of estimations for dynamic mass density and bulk modulus(leading to estimation of acoustic parameters forthe Johnson-Champoux-Allard-Lafarge model)

Some propositions for ISO 10534-2 revision(Impedance tube measurements)

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Details

Often read in current standards:"Inter-laboratory experiments are planned"

Ongoing work:Inter-laboratory test started (more than 10 labs, 5 different materials). First results should be presented in 2017(probably during next SAPEM in Le Mans  ).

Concerning elastic parameters

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Thank you for your attention

 

luc.jaouen@matelys.com

@ ljaouen on  

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