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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)
10
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)
11
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)
12
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
13
