GB/T 12060.21-2025Sound system equipment - Part 21: Acoustical (output-based)measurements (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 21 of GB/T 12060 "Sound system equipment". GB/T 12060 has published the following parts.

--- Part 1: Overview;

--- Part 2: Interpretation of general terms and calculation methods;

--- Part 3: Audio amplifier measurement methods;

--- Part 4: Microphone measurement methods;

--- Part 5: Test methods for main performance of loudspeakers;

--- Part 7: Measurement methods for headphones and earphones;

--- Part 9: Measurement methods for artificial reverberation, time delay and frequency shift devices;

--- Part 11: Application of connectors for interconnection of acoustic system equipment;

--- Part 13: Loudspeaker listening test;

--- Part 16: Objective evaluation of speech intelligibility through the speech transmission index;

--- Part 21: Output-based acoustic measurements.

This document is modified to adopt IEC 60268-21:2018 "Sound system equipment Part 21: Output-based acoustic measurements".

The technical differences between this document and IEC 60268-21:2018 and the reasons are as follows.

--- Added the abbreviations "EIHD", "EITHD", "HOHD", "IMD", "OCT" and "THD" (see 3.2) to facilitate the use of the standard;

--- Added normative references GB/T 12060.11 (see 5.4), GB/T 15212 (see 5.4) and IEC 63034:2020 (see 9.3~9.5, 10.2.1, 13.1), to adapt to my country's technical conditions;

--- Changed "free field conditions", "semi-free field conditions", "simulated free field conditions" and "far field conditions" (see 9.2, 9.3, 9.4 and 10.2.1) to adapt to my country's technical conditions;

--- Changed the evaluative description of near-field measurement (see 10.2.2.1) to adapt to the writing specifications of my country's national standards;

--- Changed the signs of the quantities "harmonic distortion", "intermodulation distortion under dual frequency excitation", "multitone distortion" and "impulse distortion" (see No. 21 Chapter 24) to adapt to the writing specifications of my country's national standards.

The following editorial changes were made to this document.

--- Corrected the formula of Hann burst signal and added the explanation of Hann window (see 8.8);

--- Changed the description of "pulse signal" in "test signal" (see 8.9);

--- Correct "long-term" to "short-term" (see 19.4.2);

--- Correct "Hlinf,r,umax" to "Hlinf,r,alpha umax" [see 19.4.4b)];

--- Combine the explanation of c in formula (31) into item b) (see 19.7.2);

--- Correct "phi 1=theta 2" to "phi 1=phi 2" (see 20.2.2.1);

--- Corrected the formula for output sound power [20.4.2b)];

--- Correct the "logarithmic ordinate (vertical) axis" to "logarithmic abscissa (horizontal) axis" (see 20.7.2);

--- Correct "logarithmic horizontal coordinate (y-axis)" to "logarithmic horizontal coordinate (x-axis)" (see 21.4.2, 21.5.2);

--- Correct "ETHD" in the note to "EIHD" (see 21.7.1);

--- Corrected the formula for expressing amplitude modulation distortion as a percentage [see 22.3.2f)];

--- Supplemented the explanation of uncertainty (see Appendix A);

--- GB/T 12060.7 replaced IEC 60268-7 (see 13.1) and GB/T 27418-2017 replaced ISO /IEC Guide98-3 (see 12.2, Appendix A);

--- Corrected the formula for the output sound power at frequency f (see E.4).

Introduction

GB/T 12060 "Sound System Equipment" is a basic standard that regulates the technical requirements and testing methods of sound system equipment in my country.

12060 (all parts) aims to establish a technical specification system covering the entire process of acoustic system equipment design, production, testing and application.

Acoustic product performance parameters, test conditions, safety requirements and compatibility criteria are planned to consist of twenty parts.

--- Part 1: Overview;

--- Part 2: Interpretation of general terms and calculation methods;

--- Part 3: Audio amplifier measurement methods;

--- Part 4: Microphone measurement methods;

--- Part 5: Test methods for main performance of loudspeakers;

--- Part 6: Auxiliary passive components;

--- Part 7: Measurement methods for headphones and earphones;

--- Part 8: Automatic gain control devices;

--- Part 9: Measurement methods for artificial reverberation, time delay and frequency shift devices;

--- Part 10: Peak programme level meter;

--- Part 11: Application of connectors for interconnection of acoustic system equipment;

--- Part 12: Application of connectors for broadcasting and similar sound systems;

--- Part 13: Loudspeaker listening test;

--- Part 16: Objective evaluation of speech intelligibility through the speech transmission index;

--- Part 17: Standard volume meter;

--- Part 18: Peak programme level meter - Digital audio peak level meter;

--- Part 21: Output-based acoustic measurements;

--- Part 22: Electrical and mechanical measurements on transducers;

--- Part 23: Televisions and monitors-Speaker systems;

--- Part 24: Headphones and earphones - Active acoustic noise reduction characteristics.

As the use of loudspeakers, headphones, and other drivers grows, new measurement techniques are needed to evaluate these systems.

A series of examples, all of which require new measurement techniques.

- Limited access to transducer electrical terminals The high integration of electrical, acoustic and mechanical components limits access to the transducer's electrical terminals.

- Analog or digital audio input signal Audio input can be analog or digital in various formats.

- Delays and other types of distortion associated with digital signal processing Digital signal processing is used to modify the transfer behavior of passive systems and generate the desired acoustic output, which may ultimately be produced in analog devices.

- Over-balancing Excessive equalization may cause the transducer to operate in the large signal domain, resulting in thermal and nonlinear effects.

- Active protection Active protection attenuates input signals to avoid mechanical and thermal overload of the transducer and other components.

- Other transducer principles While most loudspeaker systems use electrodynamic transducers with moving coils, there is a need to expand the application to electrostatic, electromagnetic, and Other transduction principles.

- Other mechanical and acoustic components In order to improve the sound radiation, closed boxes, duct reflex boxes, passive radiation reflex boxes, horns, waveguides, flat plates and other mechanical and Acoustic elements.

- Pulse distortion Imperfections in manufacturing (such as voice coil friction) or operation under overload conditions may cause pulse distortion, which can have a significant impact on perception.

The sound quality of the sound is greatly affected, but it cannot be detected by traditional measurements (such as total harmonic distortion).

- Directivity characteristics and complex near-field properties By considering the complex near-field properties as a supplement to existing far-field measurement techniques, a comprehensive evaluation of professional equipment can be achieved, including In addition, for devices used in the near field, such as handheld personal audio devices (e.g. laptops, tablets computers, smartphones, and other portable acoustic systems need to be evaluated in a manner appropriate to their intended use.

1 Scope

This document describes the specifications for passive and active sound systems (such as loudspeaker units, televisions, multimedia equipment, personal portable audio equipment, etc.)

The device under test (DUT) can consist of electronic components and passive drivers.

The electrical input signal is first processed by electronic components for analog and digital signal processing, and then converted into an acoustic output signal by a passive driver.

This document describes physical measurements that can evaluate any analog or digital input signal of the DUT at any point in the near and far fields of the system.

The physical measurement of the transfer behavior between the signal and the acoustic output. This includes measuring the DUT in both the small signal domain and the large signal domain.

When performing a physical evaluation, the impact of the acoustic boundary conditions of the target application (e.g., the interior of a car) may also be considered. This document does not evaluate the effects of the reproduced sound.

Perceptual and cognitive evaluation and the impact of perceived sound quality.

NOTE According to reference [1], some of the measurement methods defined in this document can be applied to headphones, headphone-microphone combinations, earphones and headphone-microphone combinations.

This document does not apply to microphones and other sensors. This document does not require the acquisition of state variables (voltage, current) at the electrical terminals of the transducer.

Sensitivity, electrical input power and other characteristics based on electrical impedance are described in a separate standard document, IEC 60268-22, which is dedicated to Electrical and mechanical measurements.

2 Normative references

The contents of the following documents constitute 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.

GB/T 321 Priority numbers and priority number systems (GB/T 321-2005, ISO 3:1973, IDT)

GB/T 6881-2023 Acoustics - Determination of sound power level and sound energy level of noise source by sound pressure method - Reverberation chamber precision method (ISO 3741. 2010, IDT)

GB/T 6882 Acoustics Sound pressure method for determining the sound power level and sound energy level of noise sources - Anechoic chamber and semi-anechoic chamber precision method (GB/T 6882-2016, ISO 3745:2012, IDT)

GB/T 12060.1 Sound system equipment Part 1: Overview (GB/T 12060.1-2017, IEC 60268-1:1985, MOD)

GB/T 12060.2-2011 Sound system equipment Part 2: General term interpretation and calculation methods (IEC 60268-2:1987, IDT)

GB/T 12060.11 Sound system equipment Part 11: Application of connectors for interconnection of sound system equipment (GB/T 12060.11-2012,IEC 60268-11:1987,NEQ)

GB/T 15212 Application of connectors for broadcasting and similar sound systems (GB/T 15212-1994, eqvIEC 60268-12.1987)

GB/T 20441.4 Measurement Microphones Part 4: Specifications for Working Standard Microphones (GB/T 20441.4-2006, IEC 61094-4:1995,IDT)

ISO 3741 Acoustics-Determining the sound power level and sound energy level of noise sources by sound pressure method - Reverberation chamber precision method

ISO 3744 Acoustics - Determination of sound power level and sound energy level of noise sources by sound pressure method - Engineering method for approximation to free field above reflecting surfaces

Note: GB/T 3707-2016 Acoustics - Determination of sound power level and sound energy level of noise source by sound pressure method - Engineering method for approximate free field above reflecting surface (ISO 3744:2010, IDT)