IEC TS 61949:2007

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 List of symbols
5 Equipment required
6 Test methods
  6.1 Establishing quasi-linear conditions
      6.1.1 The local distortion parameter
      6.1.2 Upper limit for quasi-linear conditions for sigma[q]
      6.1.3 Range of applicability for quasi-linear conditions
  6.2 Measurement procedure for estimated in situ exposure
      6.2.1 Identification of quasi-linear conditions
      6.2.2 Tables of limiting mean peak acoustic pressure
      6.2.3 Measurement of acoustic quantities under quasi-linear
            conditions
      6.2.4 Measurement of the scaling factor
      6.2.5 Calculation of attenuated acoustic quantities
  6.3 Uncertainties
Annex A (informative) Review of evidence
Annex B (informative) Review of alternative methods
        for managing finite-amplitude effects during
        field measurement
Annex C (informative) Parameters to quantify nonlinearity
Annex D (informative) Tables of upper limits for mean peak
        acoustic pressure for quasi-linear conditions
Bibliography

This Technical Specification describes means to allow "attenuated" acoustic quantities to be calculated under conditions where the associated acoustic measurements, made in water using standard procedures, may be accompanied by significant finite-amplitude effects. This Technical Specification establishes: - the general concept of the limits of applicability of acoustic measurements in water resulting from finite-amplitude acoustic effects; - a method to ensure that measurements are made under quasi-linear conditions in order to minimise finite-amplitude effects; - the definition of an acoustic quantity appropriate for establishing quasi-linear conditions; - a threshold value for the acoustic quantity as an upper limit for quasi-linear conditions; - a method for the estimation of attenuated acoustic quantities under conditions of nonlinear propagation in water.