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Determination of emission sound pressure level and sound power level in situ


The project will:
- develop new qualification requirements for the test environment to be used when applying a revised standard ISO 3747(to become EN later) for the determination of sound power levels in situ and to improve a Nordtest proposal for a new method, a future ISO "11205" using sound intensity for the determination of emission sound pressure levels
- carry out comparison measurements to determine the measurement uncertainty of EN ISO 11201, EN ISO 11202 and EN ISO 11204 and the new "11205" for the determination of emission sound pressure levels in situ, and ISO 3747(under revision)and ISO/DIS 9614-2 for the determination of sound power levels in situ
- analyze the test results in order to propose improvements which will reduce the measurement uncertainty of the standards tested and which later can be incorporated in revised versions of the standards
- Both random and systematic errors will be studied.

State of progress
The results indicate that the revised ISO 3747 has no significant bias and that the standard deviation of reproducibility is that of an engineering method. ISO 9614-2 yields a small underestimate of the sound power level in relation to the one determined according to ISO 3741. The reproducibility standard deviation of EN ISO 11 201 and EN ISO 11 202 is better than 2 dB. EN ISO 11 202 has a bias. The emission sound pressure levels are overestimated. The standard could be improved and the overestimate diminished if the maximum, allowable local environmental correction is increased from 2,5 dB to 4 dB. EN ISO 11 204 is difficult to implement and its range of validity is difficult to foresee. The reproducibility standard deviation of ISO 11 205 is about 2 dB. The method has a bias. Normally the emission sound pressure level is underestimated. If further restrictions are imposed not to allow several intensity vectors of about equal amplitude incident with an angular separation larger than 90 the bias will be small.

There is an urgent need to improve standards for the measurement of noise from machines which are being developed jointly by CEN TC 211 and ISO TC 43/SC 1. The standards are B-standards which according to EN ISO 12001 have to be used when elaborating product specific C-standards for use for noise declaration purposes. They are essential in order to be able to comply with the EC Machinery directive 89/392.
- The work programme has three work packages(WP):
- Improve the draft standards used for the project. This WP is carried out by the 5 main partners.
- Carry out comparison measurements on 8 different machines in different test environments. This WP is carried out by 17 laboratories from 7 different countries.
- Analyze the results and propose improvements for the standards. This WP is carried out by the 5 main partners.

Funding Scheme

CSC - Cost-sharing contracts


Swedish National Testing and ResearchInstitute SP
501 15 Boräs

Participants (4)

Bundesastalt für Arbeitsschutz
44149 Dortmund
Delta Danish Electronics, Light & Acoustics
2800 Lungby
Institut National de Recherche et de Sécurité
Avenue De Bourgogne
54501 Vandoeuvre-les-nancy
Universität Stuttgart
6,Pfaffenwaldring 6
70569 Stuttgart