Acoustics－Guide to STANDARDs on the measurement of airborne acoustical noise and evaluation of its effects on human beings
Some standard content:
National Standard of the People's Republic of China
Acoustics-Guide to standards on the measurement of airborne acoustical noise and evaluation of its effects on human beings
Acoustics-Guide to standards on the measurement of airborne acoustical noise and evaluation of its effects on human beings GB/T1425993
This standard refers to and adopts the International Standard IS2204-1979 "Acoustics-Guide to standards on the measurement of airborne acoustical noise and evaluation of its effects on human beings".
1 Subject matter and scope of application
This standard specifies the basic issues related to noise measurement and evaluation of its effects on people, and briefly introduces the commonly used measurement methods and general procedures, as well as some methods specified in other standards. This standard can be used as a guide to the relevant standards published by my country and the International Organization for Standardization. It includes noise measurement and evaluation methods, detailed experimental procedures and interpretation methods.
2 Reference standards
GB 3.101 General principles for terms, units and symbols GB3238 Levels of acoustic quantities and their reference values
GH3240 Frequencies commonly used in acoustic measurements
GB3241 1/1 and 1/3 fold pass filters for sound and vibration analysis Acoustic terms
GB3947
G33767
GB3768
GB 3769
Determination of sound power level of noise source by upper range method and engineering method Simple method for determination of sound power level of noise source
Scale and size for drawing frequency characteristic diagram and polar coordinate diagram Electrical and acoustic properties and test methods of sound level meter GB3785
GB4963
Standard equal loudness contours of pure tones in self-field
GB 6881
AcousticsDetermination of sound power level of noise sourcePrecision method and engineering method in reverberation chamberGB3096
Standard for environmental noise in urban areas
GB/T14366AcousticsMeasurement of occupational noise and evaluation of hearing loss caused by noiseGB/T14367Measurement of sound power level of noise sourceUse basic standards and rules for the formulation of noise test specificationsDetermination of sound power level of noise sourcePrecision method in anechoic chamber and semi-anechoic chamberGB6882Acoustics
GT36446Frequency weighting (D-weighting) for aircraft noise measurementGB9660Environmental standard for aircraft noise around airportsGB9661
Measurement method of aircraft noise around airports
Acoustics-Force method for calculating loudness levelWww.bzxZ.net
ISO 532
Evaluation of the impact of noise on speech intelligibility
1S0/TR 3352
Approved by the State Administration of Technical Supervision on March 17, 1993 and implemented on December 1, 1993
m.IEC804 Integrating Average Sound Level Meter
3 Classification of Noise Problems
3.1 Human Part Noise problems can be divided into two categories
GB/T 1425993
3.11 Determination of the size and characteristics of the noise radiated by one or more noise sources, or the prediction of the performance of the sound source under specified conditions. For this type of problem, the purpose of noise measurement is to determine certain physical quantities, usually the sound pressure level at a certain point or the sound power level of the sound source. The characteristics of noise can be described by the relationship between the frequency spectrum and the sound level and time, as well as the characteristics of the sound field. 3..1.2 Evaluation and prediction of various effects of noise on people. For this type of problem, the purpose of noise measurement is to obtain a quantity that represents the relationship between the size of the sound stimulus and the effect of noise on people. 3.2 Overview The problems in 3.1.1 are mainly related to the generation and propagation of noise. The problems in 3.1.2 are mainly related to the reception of noise. It must be emphasized that these two types of problems are not mutually exclusive, because a specific noise problem is usually related to both types of problems. For example, the purpose of many noise treatments is to reduce the noise radiated by the sound source to an acceptable level of impact on people. 4 Classification of channel sound characteristics
The characteristics of noise can be described by its spectrum, the change of sound level over time, and the characteristics of the sound field. Many noises have a continuous spectrum, that is, the sound energy is relatively evenly distributed in most of the audible sound frequency range. In some cases, single-frequency sounds in the noise can be clearly heard. The most commonly encountered noise in practice can be classified according to the following characteristics: 4.1 Spectrum
4.1.1 Continuous spectrum
4.1.2 Spectrum with audible single-frequency sound
4.2 Time relationship
4.2.1 Steady-state noise: noise with negligible small sound level fluctuations during the observation time. 4.2.2 Non-steady-state noise: noise with a large sound level fluctuation during the observation time. The fluctuating noises often encountered in practice, intermittent noise and impulse noise are non-steady-state noises.
4.2.2.1 Fluctuating noise: noise with a sound level that continuously changes within a fairly large range during the observation time. 4.2.2.2 Intermittent noise: noise with a sound level that suddenly drops to the background sound level several times during the observation time, and the time when the sound level is different from the ambient sound level is 1 s minus 1 s. 4.2.2.3 Impulse noise: noise composed of one or more distinct sounds, each burst lasting less than about 1s. 4.2.2.3.1 Quasi-steady-state impulse noise: a series of bursts with similar amplitudes and intervals less than 0.2s. 4.2.2.3.2 Independent bursts: including sounds with constant and nearly constant waveform amplitudes, or bursts with transient decay. 4.3 Characteristics of sound fields
4.3.1 Free field: a sound field in an isotropic homogeneous medium where the boundary effect can be ignored. 4.3.2 Reverberation field: a part of the sound field where the direct sound radiated by the sound source can be ignored during the test. 4.3.3 Semi-reverberation sound field: most of the sound field in a large room with ordinary reflecting surfaces. 4.3.4 Hemispherical divergent field: a sound field radiated by an omnidirectional sound source located near a hard reflecting plane (usually the ground) but with no other objects around. 5 Physical measurement of noise
The measurement method is based on:
the characteristics of the noise problem (see Chapter 3);
the characteristics of the noise (see Chapter 4) and the characteristics of the sound source; c. the degree of rigor required to describe the noise problem. 5.1 Noise problems belonging to 3.1.1
This type of problem generally requires determining the characteristics of the noise source and the noise radiated by the noise source. 5.1.1 Measurement
GB/T 14259-93
To solve this problem, the relationship between the sound pressure level (dB, the reference value is 20Pa) and time is measured. The sound level can be measured in a wide band or a narrow band covering the entire audible frequency range. The width of these bands is 1/1 or 1/3 octave or narrower.
The sound pressure level obtained in a specific band is called the band sound level. After passing through a specific weighting network in the measurement system, the number read is called the sound level. The term sound level is used only when there is no danger of mixing between levels of different magnitudes, such as sound pressure and power. Note: A-weighting network is commonly used (see GB3785). The digital sound level read out, expressed in decibels, is usually called dB(A). Aviation noise is measured with I-weighting (see G136446).
5.1.2 Choice of measurement method
The choice of measurement method depends on the type of sound source and its environment, the characteristics of the noise and the degree of rigor of the required description. 5.1.2.1 Sound source and environment
The International Organization for Standardization and my country's State Administration of Technical Supervision have developed some standards for noise measurement, including information on the selection of appropriate measurement methods, measurement points, corrections for background noise, and research results on some noise sources and environments such as machinery, rotating motors, vehicles and aircraft.
5.1.2.2 Characteristics of noise
The various types of noise are listed according to their characteristics (see Chapter 4) according to the difficulty of measurement. The steps for measuring steady-state noise are relatively simple and the method is mature. The best way to measure the most fluctuating noise is to use an integrating average sound level meter to read the equivalent continuous sound pressure level within a fixed time. The method for measuring impulse noise is relatively complex and not yet mature. 5.1.2.3 Rigorousness of description
Rigorous analysis of noise problems requires recording the frequency band sound pressure levels in the problem band measured at appropriate microphone positions and appropriate time intervals. For some problems, such rigorous analysis is unnecessary. It is sufficient to measure the noise with simple measurement steps. Therefore, the choice of method depends on the rigor of the description required for the noise to be determined. 5.1.3 Available methods
Available methods can be classified according to the requirements for the measurement environment, the number of instruments and the amount of labor. Due to the complexity of noise sources and sound fields, it is impossible to specify the general relationship between these requirements and the overall accuracy of the results obtained. Information on the accuracy obtained by using specific measurement methods for different types of noise can be found in relevant standards and experimental specifications. Three methods are introduced below, which depend on the equipment and labor required. For convenience, a grade is assigned to each method, and the grade system is similar to GB3785.
5.1.3.1 Survey method (level 3)
This method requires simple equipment and takes less time; it can be used to compare noise sources of similar nature. The sound field is described by the sound level measured by the sound level meter, with only a limited number of measurement points, and no detailed analysis of the acoustic environment is made. However, the time relationship of the measured noise should be recorded.
Usually, the reading of the sound level meter gives the weighted sound level, bandwidth sound pressure level or equivalent continuous A sound level. GB3785 gives the specifications of the sound level meter. The use of Class 2 sound level meters is permitted.
Generally speaking, if noise reduction measures are to be evaluated, information on the band sound pressure level is also meaningful. 5.1.3.2 Engineering Method (Class 2)
In this method, in addition to measuring the sound level or sound pressure level, the frequency band sound pressure level is also measured. The acoustic environment should be analyzed to determine its influence on the measurement. The measurement point and frequency range are selected based on the characteristics of the sound source and its working environment. During the observation process, the time relationship of the sound level should be kept in mind. The measuring instruments used should comply with the provisions of GB3785 and GB3241. This method requires the use of Class 1 sound level meters and Class 1 integral average sound level meters.
The information provided by the above method is usually sufficient for the use of engineering measures in many cases, such as noise reduction plans. Note that if the data do not use engineering measures, it is not required to measure the band sound pressure level. 5.1.3.3 Precision method (<1 level)
.GB/T 14259-93
This method gives the most complete description of the noise problem. In addition to the sound level or sound pressure level, the sound pressure level of the frequency band should be measured. According to the duration and fluctuation characteristics of the noise, it should be recorded at an appropriate time period. The acoustic environment should be carefully analyzed, and the measurement points and frequency range should be selected based on the nature of the noise source and the environment. If possible, the impact of the environment on the measurement should be analyzed. This can be measured under controlled laboratory conditions, such as in a self-reverberation field and a reverberation room. The precision method is used when a close description of the sound field is required: the instruments used should be consistent with GB3785, IEC:804 and GB3241. For some problems, such as the measurement of impulse noise, other standardized instruments can be used. This method requires the use of a zero-level sound level meter and a zero-level integrating average sound level meter.
5.1.4 Description of results
Measurements made using the survey method can calculate the average sound level. Guidance for making such calculations is given in GB3768. Measurements made using engineering and precision methods can calculate the average sound pressure level of broadband or narrowband noise. If the environment is appropriate, the sound power level and directivity of the sound source can also be calculated. Guidance for calculations can be found in GB/T14367. Fluctuating and intermittent noise can be described by equivalent continuous A-level or time distribution function of sound pressure level. Measurements made using precision methods can also evaluate the characteristics of impulse noise. The sound power level of the sound source is precisely calculated and its directivity is determined.
When comparing data measured by the methods described in this standard with each other or with other acoustic data, care should be taken to ensure that the comparison is valid in all aspects. This is especially true when comparing with other set values or specified values. 5.2 Acoustic problems belonging to 3.1.2
This type of problem is to determine the effects of noise on people. These effects cannot be directly measured using existing physical instruments, but the methods discussed in Section 6.2 can be used to collect data from which an approximate measure of the effects of noise on people can be obtained. 6 Evaluation of the effects of noise on people
6.1 The quantities to be determined
of the effects of noise on people include:
a, A-weighted sound level,
b, loudness level (L) of noise
. Perceived noise level (LP) of noise
d. Risk of hearing loss caused by noise 1
The interference of noise with people's activities (such as talking, working, resting or sleeping). e
6.2 Approximate measurement methods linking the physical characteristics of noise to subjective effects "Conversion" can be achieved by calculation or measuring an electrical network with specified characteristics in the instrument, or a combination of these methods. The results obtained are usually valid only within a limited range of situations corresponding to the method used, and even within this range, they are often only approximate characteristics. 6.2.1 A-weighted sound level
An equal loudness curve related to the sound level. This is the simplest method for estimating the impact of noise on the base equipment. Note that as long as the characteristics of the noise are similar, the sound level measurement is more useful, especially the data obtained by using the A-weighting network, and the noise is ranked according to the loudness level. It should be emphasized that the value measured in this way is not the loudness paper, but the A-weighted sound level expressed in decibels. 6.2.2 Loudness level and loudness
The loudness level () of a sound signal expressed in this way is defined as the sound pressure level of a 1 kHz pure tone judged as equally loud by a normal listener under standard listening conditions (the reference value is 20 μPa). Loudness expressed in sones (N) is a digital representation of the sound intensity, which is proportional to the subjective quantity judged by a normal listener. 1 sone is equal to the loudness of a sound with a loudness level of 40 s.
For the approximate calculation method of the loudness level and loudness of steady-state noise, see ISC>532. The data required for the calculation are the 1/3 or 1/1 octave band positive level.
Note: The calculated results are consistent with the results obtained by direct subjective measurement according to the regulations, especially for steady-state noise with obvious narrow spectral peaks. In some cases, there may be a slight deviation between the calculated loudness level and the results obtained by measurement according to the regulations. 6.2.3 Perceived noise level and noisiness
The perceived noise level (Le) of an acoustic signal expressed in decibels is defined as the acoustic noise level (base 20 μPa) of an octave band of noise with a center frequency of 1 kHz coming from the front and subjectively judged to have the same perceptual loudness as the test signal. Noiseiness expressed in na is a number that is proportional to the subjective quantity of disturbance caused by the noise. 1 na is equal to the perceived noisiness of noise with a perceived noise level of AotB.
For the calculation method of perceived noise level, see GB9661. This method was developed for the description of aircraft noise. Note: (1) The data required for the calculation of perceived noise level are the sound pressure levels in the 1/3 octave bands. When the presence of audible monotonic noise is to be considered, the calculation method is modified and the result is called the tone-corrected perceived noise level (LTN). If the duration of the aircraft overflight is further considered, another calculation method is used, which is essentially to add the values of LTM obtained at intervals of U.5. The result is called the effective perceived noise level (LiHr). A simple and direct method of approximating the perceived noise level is to use the D-weighting network in the test equipment and the formula IP-In+1, where L is the D-weighted sound level. This method does not provide monotonic correction. In most cases, the A-weighted sound level can be used to select cases with similar characteristics in terms of perceived noise level. 6.2.4 Annoyance caused by noise
Based on physical measurement: The problems of evaluating noise according to its annoyance are so complex that existing knowledge allows only very approximate solutions. The basic aspects of this problem have been studied in GB3096, which provides a basis for the relevant management departments to formulate the permissible noise limits under various conditions. The method described in
is effective for estimating the public's response to noise inside and outside homes, offices, shops, canteens and factories. 6.2.5 Interference with speech communication
The interference with speech communication caused by noise can be estimated by calculating a quantity called the clarity index. The clarity index is used to derive the speech intelligibility under noise conditions. The calculation requires the frequency band sound pressure level of the noise and other information. The detailed calculation method can be found in the relevant acoustic literature. The method is not very complicated. For steady-state noise with a wide-band spectrum, the calculated results are in good agreement with the above observed results. There are two relatively simple methods that can be used, the measurement of equivalent continuous A-weighted sound level and the measurement of the sub-band sound pressure level based on the center frequency of 500, 1000, 2000 and 4000 Hz. The average value of the sound pressure level in these frequency bands is called the Speech Interference Level (SIL), see the relevant regulations in ISO/TR3352.
6.2.6 Evaluation of occupational noise for hearing protection
The damage to hearing sensitivity caused by noise exposure varies greatly among different people. Not every situation can be predicted.Therefore, when determining the permissible limit of noise exposure, the permissible limit should be selected and properly explained. This issue is addressed in GB/T14366, which details the calculation method of the expected permanent changes in hearing (NIPTS) caused by noise exposure at different sound levels and different times for adult populations. At the same time, when the hearing threshold of the commonly used measurement hearing frequency or the combination of these frequencies exceeds a certain value, this standard also provides a basis for various formulas for calculating hearing impairment. Additional explanation:
This standard was proposed and coordinated by the National Technical Committee for Acoustic Standardization. This standard was developed by the Institute of Acoustics, Chinese Academy of Sciences, and was jointly compiled by Nanjing University of Applied Sciences, Tongji University of Applied Sciences, and Beijing Institute of Labor and Social Security. The main drafter of this standard is Zhang Ruwei.
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