BS EN 61094-3:2016:2017 Edition
$167.15
Electroacoustics. Measurement microphones – Primary method for free-field calibration of laboratory standard microphones by the reciprocity technique
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 36 |
This part of IEC 61094
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specifies a primary method of determining the complex free-field sensitivity of laboratory standard microphones so as to establish a reproducible and accurate basis for the measurement of sound pressure under free-field conditions,
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is applicable to laboratory standard microphones meeting the requirements of IEC 61094‑1 ,
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is intended for use by laboratories with highly experienced staff and specialized equipment.
NOTE
The calibration principle described in this part of IEC 61094 is also applicable to working standard microphones, preferably used without their protection grid.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 6 | Blank Page |
| 7 | English CONTENTS |
| 9 | FOREWORD |
| 11 | 1 Scope 2 Normative references 3 Terms and definitions |
| 12 | 4 Reference environmental conditions 5 Principles of free-field calibration by reciprocity 5.1 General principles 5.1.1 General 5.1.2 General principles using three microphones |
| 13 | 5.1.3 General principles using two microphones and an auxiliary sound source 5.2 Basic expressions |
| 14 | 5.3 Insert voltage technique 5.4 Free-field receiving characteristics of a microphone Figures Figure 1 – Equivalent circuit for a receiving microphone under free-field conditions |
| 15 | 5.5 Free-field transmitting characteristics of a microphone Figure 2 – Equivalent circuit for a transmitting microphone under free-field conditions |
| 16 | 5.6 Reciprocity procedure 5.7 Final expressions for the free-field sensitivity 5.7.1 Method using three microphones |
| 17 | 5.7.2 Method using two microphones and an auxiliary sound source 6 Factors influencing the free-field sensitivity 6.1 General 6.2 Polarizing voltage 6.3 Shield configuration |
| 18 | 6.4 Acoustic conditions 6.5 Position of the acoustic centre of a microphone |
| 19 | 6.6 Dependence on environmental conditions 6.6.1 General 6.6.2 Static pressure 6.6.3 Temperature 6.6.4 Humidity 6.6.5 Transformation to reference environmental conditions |
| 20 | 6.7 Considerations concerning measurement space 7 Calibration uncertainty components 7.1 General 7.2 Electrical transfer impedance 7.3 Deviations from ideal free-field conditions |
| 21 | 7.4 Attenuation of sound in air 7.5 Polarizing voltage 7.6 Physical properties of air 7.7 Imperfection of theory |
| 22 | 7.8 Uncertainty on free-field sensitivity level Tables Table 1 – Uncertainty components |
| 24 | Annex A (informative) Values for the position of the acoustic centre Figure A.1 – Example of the estimated values of the acoustic centres of LS1P and LS2aP microphones given in the bibliographical references for Annex A |
| 25 | Annex B (normative) Values of the air attenuation coefficient B.1 General B.2 Calculation procedure |
| 27 | Table B.1 – Values for attenuation of sound pressure in air (in dB/m) |
| 28 | Annex C (informative) Environmental influence on the sensitivity of microphones C.1 General C.2 Dependence on static pressure C.3 Dependence on temperature |
| 30 | Annex D (informative) Application of time selective techniques for removal of unwanted reflections and acoustic interference between microphones D.1 General D.2 Practical considerations D.2.1 Signal-to-noise ratio D.2.2 Reflections from walls and measurement rig |
| 31 | D.3 Frequency limitations D.3.1 General D.3.2 Measurements based on frequency sweeps D.3.3 Measurements based on pure tones |
| 32 | D.4 Generating missing portions of the frequency response previous to transforming to the time-domain. D.4.1 General D.4.2 Missing frequencies below the minimum measurement frequency D.4.3 Missing frequencies above the maximum measured frequency |
| 33 | D.4.4 Filtering the extended frequency response |
| 34 | Bibliography |
