BS EN IEC 60268-21:2018:2019 Edition
$215.11
Sound system equipment – Acoustical (output-based) measurements
| Published By | Publication Date | Number of Pages |
| BSI | 2019 | 84 |
This part of IEC 60268 specifies an acoustical measurement method that applies to electroacoustical transducers and passive and active sound systems, such as loudspeakers, TV-sets, multi-media devices, personal portable audio devices, automotive sound systems and professional equipment. The device under test (DUT) can be comprised of electrical components performing analogue and digital signal processing prior to the passive actuators performing a transduction of the electrical input into an acoustical output signal. This document describes only physical measurements that assess the transfer behaviour of the DUT between an arbitrary analogue or digital input signal and the acoustical output at any point in the near and far field of the system. This includes operating the DUT in both the small and large signal domains. The influence of the acoustical boundary conditions of the target application (e.g. car interior) can also be considered in the physical evaluation of the sound system. This document does not assess the perception and cognitive evaluation of the reproduced sound and the impact of perceived sound quality.
NOTE Some measurement methods defined in this document can be applied to headphones, headsets, earphones and earsets in accordance with [1]1. This document does not apply to microphones and other sensors. This document does not require access to the state variables (voltage, current) at the electrical terminals of the transducer. Sensitivity, electric input power and other characteristics based on the electrical impedance will be described in a separate future standard document, IEC 60268-22, dedicated to electrical and mechanical measurements.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 5 | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications |
| 7 | CONTENTS |
| 13 | FOREWORD |
| 15 | INTRODUCTION |
| 16 | 1 Scope 2 Normative references |
| 17 | 3 Terms, definitions and abbreviated terms 3.1 Terms and definitions 3.2 Abbreviated terms 4 Type description 5 Physical characteristics 5.1 Marking of terminals and controls 5.2 Dimensions 5.3 Mass |
| 18 | 5.4 Connectors and cable assemblies 6 Design data 7 Conditions 7.1 Rated conditions 7.2 Climatic conditions 7.3 Normal measuring conditions |
| 19 | 8 Test signals 8.1 General 8.2 Sinusoidal chirp |
| 20 | 8.3 Steady-state single-tone signal 8.4 Steady-state two-tone signal 8.5 Sparse multi-tone complex |
| 21 | 8.6 Broadband noise signal 8.7 Narrow-band noise signal 8.8 Hann-burst signal |
| 22 | 8.9 Impulsive signal 9 Acoustical environment 9.1 General 9.2 Free-field conditions 9.3 Half-space, free-field conditions 9.4 Simulated free-field conditions 9.5 Half-space simulated free-field conditions |
| 23 | 9.6 Diffuse sound field conditions 9.7 Target application conditions 10 Positioning of the DUT 10.1 Rated geometrical conditions 10.1.1 General 10.1.2 Reference plane and normal vector 10.1.3 Reference point Figures Figure 1 – Rated conditions used to describe the position ofthe DUT in the coordinate system |
| 24 | 10.1.4 Reference axis 10.1.5 Orientation vector 10.1.6 Evaluation point 10.1.7 Evaluation distance Figure 2 – Recommended position and orientation of the DUT |
| 25 | 10.2 Measuring distance between DUT and microphone 10.2.2 Near-field conditions 10.2.3 Diffuse field conditions |
| 26 | 10.2.4 Target application condition 11 Measurement equipment and test results 12 Accuracy of the acoustical measurement 12.1 General 12.2 Measurement uncertainty |
| 27 | 13 Mounting of the DUT 13.1 Mounting and acoustic loading of drive units 13.2 Mounting and acoustic loading of an electro-acoustic system |
| 28 | 14 Preconditioning 15 Rated ambient conditions 15.1 Temperature ranges 15.1.1 Performance limited temperature range 15.1.2 Damage limited temperature range 15.2 Humidity ranges 15.2.1 Relative humidity range 15.2.2 Damage limited humidity range 16 Rated frequency range 17 Input signal 17.1 Rated maximum input value 17.1.1 Condition to be specified |
| 29 | 17.1.2 Direct measurement |
| 30 | 17.1.3 Indirect measurement based on SPLmax 17.2 Maximum input level |
| 31 | 18 Sound-pressure output 18.1 Rated maximum sound pressure 18.1.1 Conditions to be specified 18.1.2 Direct measurement |
| 32 | 18.1.3 Indirect measurement based on maximum input value 18.2 Rated maximum sound-pressure level 18.3 Short term maximum sound pressure level 18.3.1 Conditions to be specified |
| 33 | 18.3.2 Method of measurement 18.4 Long term maximum sound pressure level 18.4.1 Conditions to be specified |
| 34 | 18.4.2 Method of measurement 18.5 Sound pressure in a stated frequency band 18.5.1 Condition to be specified 18.5.2 Method of measurement |
| 35 | 18.6 Sound-pressure level in a stated frequency band 18.7 Mean sound-pressure in a stated frequency range 18.7.1 Condition to be specified 18.7.2 Method of measurement 18.8 Mean sound-pressure level in a stated frequency range 19 Frequency response of the fundamental component 19.1 Transfer function 19.1.1 Conditions to be specified 19.1.2 Method of measurements |
| 37 | 19.2 SPL frequency response 19.2.1 Conditions to be specified 19.2.2 Method of measurement |
| 38 | 19.3 Time-varying amplitude compression of the fundamental component 19.3.1 General 19.3.2 Method of measurement 19.4 Amplitude compression at maximum input 19.4.1 Short term amplitude compression 19.4.2 Method of measurement |
| 39 | 19.4.3 Long-term amplitude compression 19.4.4 Method of measurement 19.5 Corrections based on a free-field reference measurement 19.5.1 General 19.5.2 Correction of the measured sound pressure signal |
| 40 | 19.5.3 Correction of the amplitude response |
| 41 | 19.6 Effective frequency range 19.6.1 Conditions to be specified 19.6.2 Method of measurement 19.7 Internal latency 19.7.1 Conditions to be specified 19.7.2 Methods of measurement |
| 42 | 20 Directional characteristics 20.1 General 20.2 Direct sound field in 3D space 20.2.1 Directional transfer function 20.2.2 Extrapolated far-field data |
| 43 | 20.2.3 Parameters of the holographic sound field expansion |
| 44 | 20.2.4 Extrapolated near-field data 20.3 Directional far field characteristics 20.3.1 Directional factor Figure 3 – Valid region of expansion of the sound pressure p(r)at the observation point r at the distance r > a |
| 46 | 20.3.2 Directional gain 20.3.3 Directivity factor 20.3.4 Directivity index |
| 47 | 20.4 Acoustic output power 20.4.1 Conditions to be specified 20.4.2 Methods of measurement |
| 49 | 20.5 Sound power level 20.6 Mean acoustic output power in a frequency band 20.6.1 Conditions to be specified 20.6.2 Method of measurement 20.7 Radiation angle 20.7.1 Conditions to be specified 20.7.2 Method of measurement |
| 50 | 20.8 Coverage angle or angles 20.8.1 Conditions to be specified 20.8.2 Method of measurement 20.9 Mean sound pressure level in an acoustical zone 20.9.1 General 20.9.2 Method of measurement |
| 51 | 21 Harmonic distortion 21.1 General 21.2 Nth-order harmonic component 21.2.1 Conditions to be specified 21.2.2 Method of measurement |
| 52 | 21.3 Total harmonic components 21.3.1 Conditions to be specified 21.3.2 Method of measurement 21.4 Total harmonic distortion 21.4.1 Conditions to be specified 21.4.2 Method of measurement |
| 53 | 21.5 Higher-order harmonic distortion 21.5.1 Conditions to be specified 21.5.2 Method of measurement |
| 54 | 21.6 Maximum sound pressure level limited by total harmonic distortion 21.6.1 Conditions to be specified 21.6.2 Method of measurement |
| 55 | 21.7 Nth-order equivalent input harmonic distortion component 21.7.1 Conditions to be specified 21.7.2 Method of measurement |
| 56 | 21.8 Equivalent input total harmonic distortion 21.8.1 Conditions to be specified 21.8.2 Method of measurement |
| 57 | 22 Two-tone distortion 22.1 Variation of excitation frequencies 22.2 Modulation distortion 22.2.1 Conditions to be specified 22.2.2 Method of measurement |
| 58 | 22.3 Amplitude modulation distortion 22.3.1 Conditions to be specified |
| 59 | 22.3.2 Method of measurement 23 Multi-tone distortion 23.1 Conditions to be specified |
| 60 | 23.2 Method of measurement 24 Impulsive distortion 24.1 Impulsive distortion level 24.1.1 Conditions to be specified Figure 4 – Measurement of the distortion generated by a multi-tone stimulus |
| 61 | 24.1.2 Method of measurement 24.2 Maximum impulsive distortion ratio 24.2.1 Conditions to be specified 24.2.2 Method of measurement Figure 5 – Measurement of impulsive distortion |
| 62 | 24.3 Mean impulsive distortion level 24.3.1 Conditions to be specified 24.3.2 Method of measurement 24.4 Crest factor of impulsive distortion 24.4.1 Conditions to be specified 24.4.2 Method of measurement |
| 63 | 25 Stray magnetic fields 25.1 General 25.2 Static component 25.2.1 Characteristic to be specified 25.2.2 Method of measurement |
| 64 | 25.3 Dynamic components 25.3.1 Characteristics to be specified 25.3.2 Method of measurement |
| 65 | Annex A (informative)Uncertainty analysis Figure A.1 – Relationship between tolerance limits, corresponding acceptanceintervals and the maximum permitted uncertainty of measurement, UMAX. |
| 66 | Tables Table A.1 – Example uncertainty budget – acoustical loudspeaker evaluation |
| 67 | Annex B (normative)Transducer mounting B.1 Standard baffle Figure B.1 – Standard baffle, dimensions |
| 68 | Figure B.2 – Standard baffle with chamfer Figure B.3 – Standard baffle with sub-baffle |
| 69 | B.2 Standard measuring enclosures B.2.1 General B.2.2 Type A B.2.3 Type B Figure B.4 – Standard measuring enclosure type A (net volume is about 600 l) |
| 70 | Figure B.5 – Standard measuring enclosure type B (net volume is about 450 l) |
| 71 | Annex C (normative)Simulated programme signal Figure C.1 – Block diagram of test setup for generating the simulated noise signal used for testing passive loudspeaker systems comprising a network filter |
| 72 | Table C.1 – Power spectrum of simulated programme signal in 1/3 octave bandsrated |
| 73 | Annex D (informative)Rating the maximum input and output values |
| 75 | Annex E (informative)Spherical wave expansion E.1 Coefficients of spherical wave expansion E.2 Directional factor |
| 76 | E.3 Directivity factor E.4 Acoustic output power |
| 77 | Annex F (informative)Non-linearity F.1 Equivalent harmonic input distortion F.2 Two-tone intermodulation Figure F.1 – Signal flow chart of the electro-acoustical system |
| 78 | F.3 Signal distortion generated in audio systems Figure F.2 – Variation of the frequencies of the two-tone stimulusin the intermodulation measurement Figure F.3 – Generation of the signal distortion in audio systems |
| 80 | Annex G (informative)Stray magnetic field Figure G.1 – Measuring apparatus for stray magnetic field |
| 81 | Bibliography |
