BS EN IEC 61265:2018
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Electroacoustics. Instruments for measurement of aircraft noise. Performance requirements for systems to measure sound pressure levels in noise certification of aircraft
| Published By | Publication Date | Number of Pages |
| BSI | 2018 | 30 |
IEC 61265:2018 specifies requirements for the electroacoustical performance of systems of instruments used to measure sound for the purposes of aircraft noise certification, and for other comparisons among aircraft models, and provides methods by which tests can be made periodically to verify that the performance continues to conform to the requirements within stated limits. In general, a sound measurement system for this purpose comprises a combination of instruments extending from a microphone, including its windscreen and other accessories, through data recording and processing devices to a suitable output. Different measurement systems, regardless of their composition, perform the necessary functions in different ways and operate on either analogue or digital principles. IEC 61265:2018 cancels and replaces the first edition published in 1995. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) addition of guidance for measurements for aircraft other than large transport aeroplanes; b) addition of microphones used in ground plane measurement systems; c) addition of weighted sound level measurements other than one-third-octave band measurements, for certain aircraft types; d) revision and clarification of requirements for digital audio recording; e) addition of requirements for evaluation of measurement uncertainty.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 7 | English CONTENTS |
| 9 | FOREWORD |
| 11 | INTRODUCTION |
| 12 | 1 Scope 2 Normative references 3 Terms and definitions |
| 16 | 4 Purpose Table 1 – ICAO measurement protocols (informative) |
| 17 | 5 Requirements 5.1 General 5.1.1 Output data 5.1.2 Time-pressure history 5.1.3 Measurements of sound from aircraft ground power units 5.1.4 Measurements of aircraft operations on the ground 5.2 Measurement uncertainty 5.2.1 Relationship with regulatory requirements |
| 18 | 5.2.2 Performance verification 5.2.3 Periodic tests 5.3 Reference environmental conditions 5.4 Sound calibrator 5.5 Microphone system 5.5.1 Pressure and free-field type microphones |
| 19 | 5.5.2 Grazing incidence microphone configuration |
| 20 | 5.5.3 Ground plane microphone configuration Figure 1 – Illustration of sound incidence anglesfrom the principal axis of the microphone Table 2 – Maximum difference between the free-field sensitivity level of a microphoneused in grazing-incidence microphone configuration at normal incidence andat specified sound incidence angles |
| 21 | 5.5.4 Measurement configurations 5.6 Measurement system exclusive of the microphone 5.6.1 Frequency response 5.6.2 Level linearity |
| 22 | 5.6.3 Floating-range measurement systems 5.7 Spectrum analysis system 5.7.1 Third-octave analysis 5.7.2 Time constants 5.7.3 Time offset |
| 23 | 5.7.4 Anti-aliasing 5.8 Readout device resolution 5.9 Sensitivity to various environments 5.9.1 General 5.9.2 Atmospheric pressure 5.9.3 Air temperature |
| 24 | 5.9.4 Humidity 5.9.5 Electromagnetic compatibility |
| 25 | Annex A (informative)Methods of testing the electroacoustical performanceof a measurement system A.1 General A.2 Operating conditions for test A.3 Sound calibrator A.4 Microphone system frequency response |
| 26 | A.5 Frequency response of the measurement system exclusive of the microphone A.6 Linear operating range of the measurement system exclusive of the microphone A.7 Spectrum analysis system |
| 27 | Annex B (informative)Relationship between tolerance interval, corresponding acceptance interval and the maximum permitted uncertainty of measurement Figure B.1 – Relationship between tolerance interval, corresponding acceptanceinterval and the maximum permitted uncertainty of measurement |
| 29 | Bibliography |
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