SN EN ISO 7731 : 2008

Foreword
Introduction
1 Scope
2 Normative references
3 Terms, definitions and symbols
4 Safety requirements
  4.1 General
  4.2 Recognition
      4.2.1 Introduction
      4.2.2 Audibility
      4.2.3 Distinctiveness
      4.2.4 Unambiguity
      4.2.5 Moving sources
  4.3 Review of the signal
  4.4 Recommended maximum level of the danger signal
5 Test methods
  5.1 Measurement equipment
  5.2 Objective acoustic measurements
      5.2.1 General
      5.2.2 Weighted measurements
      5.2.3 Measurements made in the frequency domain
      5.2.4 Measurement of the auditory signal with
            ambient noise present
  5.3 Subjective test method
6 Design criteria for auditory danger signals
  6.1 General
  6.2 Sound-pressure level
  6.3 Spectral characteristics
  6.4 Temporal characteristics
      6.4.1 Temporal distribution of the danger signal
      6.4.2 Temporal distribution of the frequencies
      6.4.3 Duration of the danger signals
  6.5 Information required from suppliers
Annex A (normative) Definitions of symbols
Annex B (normative) Calculation of effective masked
                       threshold
Annex C (normative) Listening test
Annex D (informative) Examples of danger signals
Annex ZA (informative) Relationship between this European
                       Standard and the Essential Requirements
                       of EU Directive 98/37 EEC
Bibliography

ISO 7731:2003 specifies the physical principles of design, ergonomic requirements and the corresponding test methods for danger signals for public and work areas in the signal reception area and gives guidelines for the design of the signals.