SN EN 61094-2 : 1993

Cooperating organizations
National foreword
Foreword
1 Scope
2 Normative references
3 Definitions
3.1 reciprocal microphone
3.2 phase angle of pressure sensitivity of a
       microphone
3.3 electrical transfer impedance
3.4 acoustic transfer impedance
3.5 coupler
4 Reference environmental conditions
5 Principles of pressure calibration by reciprocity
5.1 General principle
5.1.1 General principles using three microphones
5.1.2 General principles using two microphones and an
       auxiliary sound source
5.2 Basic expressions
5.3 Insert voltage technique
5.4 Evaluation of the acoustic transfer impedance
5.5 Heat-conduction correction
5.6 Capillary tube correction
5.7 Final expressions for the pressure sensitivity
5.7.1 Method using three microphones
5.7.2 Method using two microphones and an auxiliary
       sound source
6 Factors influencing the pressure sensitivity
6.1 General
6.2 Polarizing voltage
6.3 Ground shield reference configuration
6.4 Pressure distribution over the diaphragm
6.5 Dependence on environmental conditions
6.5.1 Static pressure
6.5.2 Temperature of microphone
6.5.3 Humidity
6.5.4 Atmospheric conditions
7 Calibration uncertainty components
7.1 General
7.2 Electrical transfer impedance
7.3 Acoustic transfer impedance
7.3.1 General
7.3.2 Coupler dimensions
7.3.3 Front cavity
7.3.4 Acoustic impedance
7.3.5 Physical quantities
7.3.6 Environmental conditions
7.3.7 Correction factors
7.4 Polarizing voltage
7.5 Uncertainty on pressure sensitivity level
Annexes
A Heat conduction in a closed cavity
B Acoustic impedance of a capillary tube
C Examples of cylindrical couplers for calibration
       of microphones
C.1 Plane-wave couplers
C.2 Large-volume couplers
D Environmental influence on the sensitivity of
       microphones
D.1 General
D.2 Dependence on static pressure
D.3 Dependence on temperature
E Methods for determining microphone parameters
E.1 Front cavity depth
E.2 Front cavity volume and equivalent volume
E.3 Acoustic impedance of the microphone
F Physical quantities
ZA (normative) Other international publications
       quoted in this standard with the references of
       the relevant European publications
National annex NA (informative) Committees responsible

Specifies a primary method for pressure calibration of laboratory standard microphones by the reciprocity technique. Coverage includes: reference environmental conditions; factors influencing the pressure sensitivity; calibration of uncertain components. Also gives detailed definitions.