NEN EN ISO 7235 : 2009

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Test facilities and requirements for instrumentation
  5.1 Purpose and types of test facilities
  5.2 Equipment for acoustic testing of silencers
  5.3 Equipment for acoustic testing of air-terminal
      units
  5.4 Equipment for flow testing
  5.5 Equipment for dynamic testing
6 Test procedures
  6.1 General
  6.2 Insertion loss
  6.3 Transmission loss
  6.4 Sound power level of the flow noise (or regenerated
      sound)
  6.5 Volume flow rate and pressure loss coefficient
7 Information to be recorded
  7.1 Description of the test object
  7.2 Instrumentation
  7.3 Sound-source equipment
  7.4 Test, substitution and transmission ducts
  7.5 Transitions
  7.6 Anechoic termination
  7.7 Reverberation room
  7.8 Acoustical test results
  7.9 Measurement uncertainty
8 Information to be reported
Annex A (normative) Design of the sound field excitation
        equipment and qualification tests
Annex B (normative) Transmission element
Annex C (normative) Duct walls and limiting insertion
        loss
Annex D (normative) Conversion of one-third-octave-band
        attenuation values to octave-band attenuation
        values
Annex E (normative) Measurements on large parallel-baffle
        silencers
Annex F (normative) Test of longitudinal attenuation
Annex G (informative) Anechoic terminations
Annex H (informative) Examples of measurement
        arrangements
Bibliography

Defines methods for determining the insertion loss, in frequency bands, of ducted silencers with and without airflow, the sound power level, in frequency bands, of the flow noise (or regenerated sound) generated by ducted silencers, the total pressure loss of silencers with airflow, and the transmission loss, in frequency bands, of air-terminal units.