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GB/T 21228.2-2023: Acoustics - Sound-scattering properties of surfaces - Part 2: Measurement of the directional diffusion coefficient in a free field
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| GB/T 21228.2-2023 | English | 384 |
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Acoustics - Sound-scattering properties of surfaces - Part 2: Measurement of the directional diffusion coefficient in a free field
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GB/T 21228.2-2023
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Basic data | Standard ID | GB/T 21228.2-2023 (GB/T21228.2-2023) | | Description (Translated English) | Acoustics - Sound-scattering properties of surfaces - Part 2: Measurement of the directional diffusion coefficient in a free field | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | A42;P31 | | Classification of International Standard | 91.120.20 | | Word Count Estimation | 20,296 | | Date of Issue | 2023-05-23 | | Date of Implementation | 2023-12-01 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 21228.2-2023: Acoustics - Sound-scattering properties of surfaces - Part 2: Measurement of the directional diffusion coefficient in a free field
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ICS 91:120:20
CCSA42;P31
National Standards of People's Republic of China
Acoustic Surface Sound Scattering Properties
Part 2: Free-field directional diffusion coefficient measurement
(ISO 17497-2:2012, IDT)
Released on 2023-05-23
2023-12-01 implementation
State Administration for Market Regulation
Released by the National Standardization Management Committee
table of contents
Preface I
Introduction II
1 Scope 1
2 Normative references 1
3 Terms and Definitions 1
4 Measuring principle 3
5 frequency range 3
6 Measurement arrangement 4
6:1 Measurement environment 4
6:2 Measurement area 5
6:3 Specimen 7
7 Test method 7
7:1 Test signal 7
7:2 Sound source and receiving equipment 7
7:3 Measurement 7
7:4 Processing of Polar Coordinate Responses 8
8 Result expression 11
8:1 Directional diffusion coefficient 11
8:2 Normalized directional diffusion coefficient 11
8:3 Calculation of area factor 12
8:4 Random incidence diffusion coefficient 12
8:5 Results expression 13
9 Test report 13
Appendix A (Normative) Requirements for Measurement Space 14
A:1 Space requirements14
A:2 Environmental conditions 14
A:3 Placement requirements 14
Reference 15
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 2 of GB/T 21228 "Sound Scattering Characteristics of Acoustic Surfaces": GB/T 21228 has issued the following parts:
--- Part 1: Measurement of scattering coefficient of random incident sound in reverberation chamber;
--- Part 2: Free field directional diffusion coefficient measurement:
This document is equivalent to ISO 17497-2:2012 "Acoustic Surface Sound Scattering Properties Part 2: Free Field Directional Diffusion Coefficient
Measurement":
The following minimal editorial changes have been made to this document:
---Changed the index number description 5 in Figure 1, and changed the "receiver" in ISO 17497-2:2012 to "receiving point trajectory (arc or
sphere)", to make the explanation clearer:
Please note that some contents of this document may refer to patents: The issuing agency of this document assumes no responsibility for identifying patents:
This document was proposed by the Chinese Academy of Sciences:
This document is under the jurisdiction of the National Acoustic Standardization Technical Committee (SAC/TC17):
This document was drafted by: Institute of Acoustics, Chinese Academy of Sciences, Tongji University, Hangzhou Aihua Intelligent Technology Co:, Ltd:, Chongqing University, Zhengzhou
Hongsen Energy Saving Technology Co:, Ltd:, Southeast University, China Academy of Building Research Co:, Ltd:, Nanjing University, Qingdao University of Technology:
The main drafters of this document: Lu Yadong, Li Xiaodong, Cheng Xiaobin, Mo Fangshuo, Xiong Wenbo, Jiang Guorong, Yu Wuzhou, Xie Hui, Zhang Jianxun, Fu Xiuzhang,
Tan Hua, Tao Jiancheng, Xu Xin, Yin Cho, Liu Bilong:
Introduction
The degree of surface sound scattering is very important in various occasions of room acoustics (such as: concert halls, recording studios, workshops and reverberation rooms, etc:): indoor
The degree of scattering and absorption is an important factor affecting the sound quality of the room: This document deals with the measurement and characterization of scattering surfaces:
GB/T 21228 is proposed to be divided into the following parts:
--- Part 1: Reverberation chamber random incident sound scattering coefficient measurement: The purpose is to describe the force from the surface caused by the surface roughness
The degree to which the acoustic reflection deviates from the specular reflection:
--- Part 2: Free field directional diffusion coefficient measurement: The aim is to describe the space of surface acoustic scattering that characterizes the quality of diffuse surfaces:
distribution characteristics:
The random incident sound scattering coefficient introduced in Part 1 of GB/T 21228 is different from the directional diffusion coefficient described in this document
The former describes the degree of sound scattering, and the latter describes the directional uniformity of sound scattering: The two are related, and they have different applications:
use the occasion:
Acoustic Surface Sound Scattering Properties
Part 2: Free-field directional diffusion coefficient measurement
1 Scope
This document describes a method for measuring the directional diffusion coefficient of a surface:
The diffusion coefficient describes the uniformity of the directional distribution of the surface reflected sound, and is an index to measure the scattering characteristics of the surface sound:
The user accounts for the sound diffusing properties of surfaces and also provides information for developers and users of predictive room acoustics models: However, the diffusion coefficient is not
Suitable directly as an input to the current diffusion algorithm in the geometric-acoustic model of the room:
This document also details methods for characterizing the sound diffusion properties of surfaces in a free field:
2 Normative references
The contents of the following documents constitute the essential provisions of this document through normative references in the text: Among them, dated references
For documents, only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to
this document:
Note: Commonly used frequencies in GB/T 3240-1982 acoustic measurement (neqISO 266:1975)
IEC 61260 Electroacoustic octave and fractional octave filters (Electroacoustics-Octave-bandandfractional-
Note: GB/T 3241-2010 Electroacoustic octave and fractional octave filters (IEC 61260:1995, MOD)
3 Terms and Definitions
The following terms and definitions apply to this document:
3:1
sound ray soundray
A line originating from the point of sound source that traces a possible direction of sound propagation:
3:2
Specular reflection specular reflection
Reflection that obeys Snel's law (that is, the angle of reflection equals the angle of incidence):
NOTE: Specular reflection can be approximated by a rigid plane much larger than the wavelength of the incident sound:
3:3
Specular reflection area specularzone
The area enclosed by the sound rays from the virtual sound source (i:e: the specific reference plane and the sound rays around the edge of the reference plane and the receiving point arc
or the area formed by the sphere):
Note 1: The reference plane is a rigid plane with the same projected shape or footprint as the surface of the test piece:
Note 2: The position where the sound rays from the virtual sound source to the receiving point pass through the diffuser is the specular reflection point (see Figure 1):
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