GB/T 20441.8-2025Electroacoustics - Measurement microphones - Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison (English PDF)

Foreword

This 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.

Introduction

The 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 method

1 Scope

This 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 references

The 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