BS 5677:1979

National foreword
Cooperating organizations
1. Scope
2. Object
3. Explanation of terms
3.1 Open circuit voltage
3.2 Pressure sensitivity of a microphone
3.2.1 Pressure sensitivity of a microphone
3.2.2 Pressure sensitivity phase angle of a microphone
3.3 Electrical impedance of a microphone
3.4 Acoustic impedance of a microphone
3.5 Equivalent volume of a microphone
3.6 Coupler
3.7 Electrical transfer impedance
3.8 Acoustic transfer impedance
3.9 Reciprocal microphone
4. Principles of pressure calibration by reciprocity
4.1 General
4.1.1 General principles using three microphones
4.1.2 General principles using two microphones and an
        auxiliary sound source
4.2 Coupler requirements
4.3 Reciprocity procedure
4.4 Evaluation of Zab
4.5 Heat-conduction correction
4.6 Capillary correction
4.7 Final expressions for the pressure sensitivity
      level
4.7.1 Method using three microphones
4.7.2 Method using two microphones and an auxiliary
        sound source
5. Absolute accuracy of calibration
5.1 General
5.2 Factors influencing the accuracy of calibration
5.2.1 Polarizing voltage
5.2.2 Static pressure
5.2.3 Frequency
5.2.4 Electrical transfer impedance
5.2.5 Heat conduction correction
5.2.6 Capillary correction
5.2.7 Cross-sectional area of the coupler
5.2.8 Effective length of the coupler
5.2.9 Effective volume of the coupler
5.2.10 Temperature of the coupler and microphones
5.2.11 Pressure distribution over the diaphragm
5.2.12 Acoustic losses
5.3 Over-all accuracy
6. Calibration methods and equipment
6.1 Coupler
6.2 Reference configuration of ground-shield
6.3 Insert voltage technique
6.4 Dependence on static pressure
6.5 Polarizing voltage
6.6 Effective length of the coupler
6.7 Acoustic impedance of the microphone
6.8 Maximum geneator voltage
6.9 Noise
Appendix A: Examples of cylindrical couplers for
calibration of microphones

Applies to laboratory standard condenser microphones with the highest obtainable accuracy for interchange of information between testing authorities.

This Recommendation describes the calibration of one-inch condenser microphones used as laboratory standards. It is restricted to reciprocity pressure calibration by the coupler method.