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Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 20441.8-2025: Electroacoustics - Measurement microphones - Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison Status: Valid
Basic dataStandard ID: GB/T 20441.8-2025 (GB/T20441.8-2025)Description (Translated English): Electroacoustics - Measurement microphones - Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: A59 Classification of International Standard: 17.140.50 Word Count Estimation: 26,253 Date of Issue: 2025-05-30 Date of Implementation: 2025-05-30 Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration GB/T 20441.8-2025: Electroacoustics - Measurement microphones - Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order. ICS 17.140.50 CCSA59 National Standard of the People's Republic of China Electroacoustic Measurement Microphones Part 8.Measurement of working standard microphones Free-field sensitivity comparison method Released on 2025-05-30 2025-05-30 Implementation State Administration for Market Regulation The National Standardization Administration issued Table of contentsPreface III Introduction IV 1 Scope 1 2 Normative references 1 3 Terms and Definitions 2 4 Reference environmental conditions 3 5 Principle of free-field calibration by comparison method 3 5.1 General Principles 3 5.2 General Principles of Sequential Excitation Method 3 5.3 General Principles of Simultaneous Excitation Method 3 6 General requirements 4 6.1 Test Space 4 6.2 Methods of establishing a free field 4 6.3 Sound Source 5 6.4 Reference Microphone 5 6.5 Monitoring Microphone 6 6.6 Test Signal 6 6.7 Mounting structure of reference microphone and microphone under test 7 7 Factors Affecting Free-Field Sensitivity 7 7.1 Overview 7 7.2 Polarization voltage 7 7.3 Microphone Acoustic Center 7 7.4 Angle of incidence and coaxiality of the sound source 7 7.5 Installation and Configuration 7 7.6 Relationship with environmental conditions 8 8 Components of calibration uncertainty 8 8.1 Overview 8 8.2 Sensitivity of the reference microphone 8 8.3 Measurement of microphone output 8 8.4 The difference in sound pressure between the microphone under test and the reference microphone 8 8.5 Effects of indirect sound 9 8.6 The impact of signal processing 9 8.7 Effects of Microphone Characteristics and Measurement System Performance 9 8.8 Uncertainty of the free-field sensitivity level 9 Appendix A (informative) Basic substitution calibration in a free-field room 11 A.1 Basic principles of the method 11 A.2 Application Example 11 A.3 Loudspeaker Source Example 12 Appendix B (Informative) Time Selection Technology 14 B.1 Basic principles 14 B.2 Step Sine Method 16 B.3 Sweep frequency excitation method 16 B.4 Random Noise Excitation Method 17 B.5 Longest Sequence (MLS) Method 18 B.6 Direct Pulse Excitation Method 18 Reference 20ForewordThis document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1.Structure and drafting rules for standardization documents" Drafting. This document is Part 8 of GB/T 20441.GB/T 20441 has been published in the following parts. --- Microphones for electroacoustic measurements Part 1.Specifications for laboratory standard microphones; --- Microphones for electroacoustic measurements Part 2.Primary method for sound pressure calibration of laboratory standard microphones using the reciprocity technique; --- Microphones for electroacoustic measurements Part 3.Primary levels for free-field calibration of laboratory standard microphones using the reciprocity technique method; --- Measurement microphones Part 4.Specifications for working standard microphones; --- Microphones for electroacoustic measurements. Part 5.Comparison method for sound pressure calibration of working standard microphones; --- Microphones for electroacoustic measurements Part 6.Electrostatic actuators for determining frequency response; --- Microphones for electroacoustic measurements Part 7.Free-field sensitivity levels and sound pressure field sensitivity levels of laboratory standard microphones The difference between --- Microphones for electroacoustic measurements Part 8.Comparison method for determining the free-field sensitivity of working standard microphones. This document is equivalent to IEC 61094-8.2012 "Measurement microphones Part 8.Comparison of the sensitivity of working standard microphones Law". The following minimal editorial changes were made to this document. --- To be consistent with the existing series of standards, the standard name is changed to "Electroacoustic Measurement Microphones Part 8.Determination of Working Standard Microphones A comparative method for the free-field sensitivity of acoustic instruments. Please note that some of the contents of this document may involve patents. The issuing organization of this document does not assume the responsibility for identifying patents. This document is proposed and coordinated by the National Electroacoustics Standardization Technical Committee (SAC/TC23). This document was drafted by. Beijing 797 Audio Co., Ltd., Institute of Acoustics, Chinese Academy of Sciences, China Institute of Metrology, The Third Research Institute of China Electronics Technology Group Corporation. The main drafters of this document are. Song Ming, Yan Xin, Li Xiaodong, Niu Feng, He Longbiao and Zhao Jing.IntroductionThe measuring microphone is a microphone with electroacoustic performance and mechanical structure that meets the specified requirements and is used in sound pressure measurement standards, sound measurement instruments and automatic sound-based In the control system, an electroacoustic transducer converts acoustic oscillations into electrical signals. The laboratory standard microphone is mainly used to establish the sound pressure level. Measurement standard; working standard microphone is mainly used as an important part of practical measuring instruments and is widely used in various acoustic measurement fields. It is widely used in the measurement of environmental noise, machine noise and workplace noise, as well as sound detection under some special conditions. It is also used for electroacoustic equipment and electrical Testing of acoustic device performance characteristics; transfer standard microphones are used to achieve the sound pressure difference between laboratory standard microphones and working standard microphones. Value passing. GB/T 20441 "Electroacoustic Measurement Microphones" is intended to define laboratory standard microphones, transfer standard microphones and working standard microphones. The performance specifications and structural requirements of the microphones are given, and the calibration methods of the sound pressure sensitivity and free field sensitivity of these measuring microphones are given. GB/T 20441 is planned to consist of 10 parts. --- Part 1.Laboratory standard microphone specification. The purpose is to determine the electroacoustic performance and mechanical dimensions of laboratory standard microphones. to standardize the calibration method and achieve comparison between laboratories. --- Part 2.Primary method for sound pressure calibration of laboratory standard microphones using the reciprocity technique. The purpose is to establish a reproducible and The basis for accurate sound pressure measurements. --- Part 3.Primary method for free-field calibration of laboratory standard microphones using the reciprocity technique. This provides the basis for reproducible and accurate sound pressure measurements under these conditions. --- Part 4.Specification for working standard microphones. The purpose is to determine the electroacoustic performance and mechanical dimensions of working standard microphones so that Used as transfer standards in acoustic measurements or as electroacoustic transducers in practical sound measurement systems. --- Part 5.Comparison method for sound pressure calibration of working standard microphones. The purpose is to compare with calibrated standard microphones Determine the sound pressure sensitivity of the working standard microphone. --- Part 6.Electrostatic actuators for determining frequency response. The purpose is to determine the performance and structure of electrostatic actuators to provide A convenient method for determining the sensitivity and frequency response of measurement microphones. --- Part 7.The difference between the free-field sensitivity level and the sound pressure sensitivity level of the laboratory standard microphone. These differences are used to determine the free-field sensitivity level of the laboratory standard microphone from the known sound pressure sensitivity level. --- Part 8.Comparison method for determining the free-field sensitivity of a working standard microphone. The purpose is to compare the free-field sensitivity of a working standard microphone with a calibrated standard microphone. The free-field sensitivity of the working standard microphone is determined by comparison with the --- Part 9.Specification for transfer standard microphones. The purpose is to determine the electroacoustic characteristics and mechanical dimensions of transfer standard microphones so that Used as transfer standards in acoustic measurements and for performance evaluation and calibration of acoustic calibrators and comparison couplers. --- Part 10.Low-frequency absolute sound pressure calibration of microphones using computable pistonphones. The purpose is to provide The measurement provides a reproducible and accurate standard. This document only specifies the method of establishing a free field, i.e., using a surface-absorbing test space and a time-selection method to obtain free field sensitivity. The various timing techniques for quantifying free-field room performance are presented in Appendix B. The principle is the same as that in GB/T 20441.5-2017 "Electroacoustic measurement microphones Part 5.Comparison method for sound pressure calibration of working standard microphones" The principles of the sequential excitation method and the simultaneous excitation method are the same, so the working group of this document did not conduct further experiments or verification. Electroacoustic Measurement Microphones Part 8.Measurement of working standard microphones Free-field sensitivity comparison method1 ScopeThis document specifies the free-field sensitivity of a working standard microphone as determined by comparison with a laboratory standard microphone or a working standard microphone. These standard microphones are calibrated in accordance with either of the following documents. ---IEC 61094-3; ---IEC 61094-2 or IEC 61094-5, and has been applied to the elements given in IEC TS61094-7; ---IEC 61094-6; ---This document. This document applies to standard microphones that meet the requirements of IEC 61094-4.This document covers microphones that are used in acoustic environments that are very close to the ideal The method is carried out in a free-field acoustic environment (e.g. a high-quality free-field room) and the results are post-processed to reduce The method simulates the free field environment by considering the influence of defects in the acoustic environment. Comparisons are possible but are beyond the scope of this document. NOTE 1 This document also applies to laboratory standard microphones that meet the requirements of IEC 61094-1, since such microphones also have requirements for the electroacoustic specifications of working standard microphones. Is satisfied. NOTE 2 This document also applies to microphone-preamplifier combinations where the measured sensitivity is related to the no-load output voltage of the preamplifier. NOTE 3 Other equipment, such as sound level meters, can be calibrated using the principles of this document but are outside the scope of this document.2 Normative referencesThe contents of the following documents constitute the essential clauses of this document through normative references in this document. For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to This document. ISO 26101 Acoustics - Test methods for the assessment of free-field environments Note. GB/T 34828-2017 Acoustic free-field environment assessment test method (ISO 26101.2012, IDT) Note. GB/T 27418-2017 Evaluation and expression of measurement uncertainty (ISO /IEC Guide 98-3..2008, MOD) Note. GB/T 20441.1-2010 Electroacoustic Measurement Microphones Part 1.Specifications for Laboratory Standard Microphones (IEC 61094-1.2000, IDT) IEC 61094-2 Electroacoustic measurement microphones Part 2.Sound pressure calibration of laboratory standard microphones using the reciprocity technique ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 20441.8-2025_English be delivered?Answer: Upon your order, we will start to translate GB/T 20441.8-2025_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. The lengthier the document the longer the lead time.Question 2: Can I share the purchased PDF of GB/T 20441.8-2025_English with my colleagues?Answer: Yes. The purchased PDF of GB/T 20441.8-2025_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. 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