Some standard content:
National Standard of the People's Republic of China
Auditory danger signals
Danger signals for work places-Auditory danger signals
UDC .654. 92
GB 1251.1—89
This standard is equivalent to the international standard ISO7731—1986 "Danger signals for work places-Auditory danger signals". 1 Subject content and scope of application
This standard specifies the safety requirements, test methods and design criteria for auditory danger signals. This standard applies to workplaces, especially workplaces with high sound level ambient noise; it does not apply to danger warnings expressed in words (such as shouting, loudspeaker broadcasts, etc.).
Special provisions on public hazards and public transportation are not affected by this standard. 2 Reference standards
GB3240 Common frequencies in acoustic measurements
GB3241 1/1 and 1/3 octave filters for sound and vibration analysis 5 Electrical and acoustic properties and test methods of sound level metersGB3785
GB3947
Terms of acoustic terms
3 Terms
3.1 Auditory danger signal The auditory danger signal indicates the beginning of the danger. If necessary, it also indicates its continuation and termination. According to the urgency of the impact of the danger on personal safety, the auditory danger signal is divided into two categories: warning auditory signal and emergency evacuation auditory signal.
3.1.1 Warning auditory signal (including pre-start warning signal) The auditory warning signal indicates a possible or ongoing danger, and also indicates the corresponding means to control and eliminate the danger and its implementation procedures. 3.1.2 Auditory emergency evacuation signal indicates an emergency situation that has begun to occur or is occurring and may cause harm, and orders people to leave the danger zone immediately in a recognizable manner.
3.2 Signal reception area The area where people can recognize and respond to auditory signals of danger. This standard does not cover various problems that may arise when auditory signals of danger are heard outside the signal reception area. 3.3 Ambient noise Ambient noise
In the signal reception area, all sounds except those produced by the generator of the danger signal. 3.4 Masked threshold (effective hearing in ambient noise) In ambient noise, it refers to the sound pressure level at which the auditory signal of danger can just be heard. The hearing impairment of the listener and the sound attenuation of the ear protectors should be taken into account.
4 Symbols
Octave center frequency, Hz;
Approved by the State Administration of Technical Supervision on March 22, 1989 and implemented on October 1, 1989
GB 1251.1—89
Lx1---Octave band sound pressure level (reference sound pressure, 20uPa), dB; IN...Ambient noise A-weighted sound level, dB; LN.o
Ambient noise octave band sound pressure level, dB;
LN,1/3cAmbient noise 1/3 octave band sound pressure level, dB; Ls.A---Accident auditory signal A-weighted sound level, dB; Ls,oi
Octave band sound pressure level of dangerous auditory signal, dB; Lr.ot
Octave band sound pressure level of masking threshold, dB;
1/3 octave band sound pressure level of masking threshold, dB;
A-weighted sound power level of dangerous auditory signal (reference sound power: 1pW), dB; d, sound attenuation of ear protector, dB;
j——lower angle code, j=1, 2,, 8; corresponding to octave center frequency: 63, 125, 250, 500, 1k, 2k, 4k, 8kHzn--— The lower angle code, n = 1, 2,, 22; corresponding to the 1/3 octave center frequency: 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.15k, 4k, 5k, 6.3k, 8kHz.5 Safety requirements
5.1 General
The characteristics of the hazard auditory signal must be that anyone in the signal receiving area can recognize and make the expected response to the signal. In order to be easy to identify, the hazard auditory signal should be different from all other auditory signals, and the emergency evacuation auditory signal should be different from all warning auditory signals.
The effectiveness of the hazard auditory signal should be checked regularly. Whenever a new auditory signal is activated or a new noise source appears, the effectiveness of the hazard auditory signal must be reviewed in time.
5.2 Identification
In order to reliably identify dangerous auditory signals, the signal must have the following characteristics: clear audibility; distinguishability; clear meaning. 5.2.1 Clear audibility
The signal must be clear and audible and exceed the masking threshold. Usually, when using A-weighted sound level analysis, the A-weighted sound level of the signal exceeds the A-weighted sound level of the ambient noise by 15dB. Using octave analysis or 1/3 octave analysis can obtain more accurate results. In most cases, using octave analysis is accurate enough.
When doing octave analysis, the signal has one or more octaves in the frequency range of 300 to 3000Hz, and the sound pressure level of the signal band exceeds the masking threshold by at least 10dB.
When doing 1/3 octave analysis, the signal has one or more 1/3 octaves in the frequency range of 300 to 3000Hz, and the sound pressure level of the signal band exceeds the masking threshold by at least 13dB. In addition, the hearing of the personnel in the signal receiving area and the use of ear protectors should also be considered. In order to ensure clear audibility for people with normal hearing and mild hearing loss, the A-weighted sound level of the signal shall generally not be lower than 65dB; when the A-weighted sound level of the signal is less than 65dB, the personnel in the receiving area can indeed identify it, then the signal can also be used. At this time, the personnel should do a listening test, see 6.2. If there are moderately deaf and severely deaf personnel in the signal receiving area, the above representatives must participate in the listening test, otherwise the signal cannot be considered to have been identified. 5.2.2 Distinguishability
Sound level, frequency characteristics and instantaneous distribution are three acoustic parameters that affect the identification of dangerous auditory signals. In the receiving area, at least two acoustic parameters of the dangerous auditory signal are significantly different from the ambient noise. 5.2.3 Clarity of meaning
The meaning of the dangerous auditory signal must be clear, and the signal cannot be similar to signals used for other purposes. The distress auditory signal emitted from the mobile distress signal source must be audible and recognizable, regardless of the 28
moving speed and number of rotations of the signal source.
6 Test method
6.1 Acoustic measurement
GB 1251.1--89
Use measuring instruments to verify whether the distress auditory signal meets the three conditions for identifying distress auditory signals in 5.2: measure the A-weighted sound level of the distress auditory signal and the ambient noise, and it can be identified when the former is 15dB greater than the latter; a.
When the A-weighted sound level measurement cannot obtain appropriate results, frequency analysis should be performed; b.
Measure the instantaneous distribution of the A-weighted sound level of the distress auditory signal. c.
The measuring instrument must comply with the provisions of GB3240, GB3241 and GB3785. The accuracy of the sound level meter is Type 2 or better. When measuring environmental noise, use "slow" time weighting. When there are fluctuations, take the maximum value. 6.2 Listening test
When all people in the signal receiving area can identify the dangerous auditory signal, it is considered that the signal meets the identification conditions of 5.2. The steps for doing a listening test in the signal receiving area are as follows: Select no less than ten subjects. If the total number of people in the signal receiving area is less than ten, all people should participate in the listening test. The subjects should include people of all age groups and people with hearing loss. People who wear ear protectors should also wear ear protectors when doing the listening test.
When doing a listening test, before sending the dangerous auditory signal, the subjects should not be notified in advance, and the time and place that are most unfavorable for listening should be selected to send it. This test should be repeated five times, and all should be able to identify it. 7 Calculation method of effective masking
The masking threshold can be calculated based on the octave band sound pressure level or 1/3 octave band sound pressure level of the ambient noise: The masking threshold Lr.oer for octave band analysis is calculated as follows: Step 1: The lowest octave j1
LT1,ot = LN1,oet
At this time, the masking threshold is equal to the octave band sound pressure level of the ambient noise. Step j: (j>1)
LTjoet = max · (LNjot; Ltj-1.ot 7. 5dB) From j2,,8
That is, the greater of the difference between the masking threshold of the (j-1)th octave band minus 7.5dB and the noise sound pressure level of the jth octave band is taken as the masking threshold of the jth octave band.
The above method is still applicable when wearing ear defenders. First, in each octave band, the octave band sound pressure levels of the ambient noise and the dangerous auditory signal are subtracted from the sound attenuation of the ear defender in the corresponding octave band, and then the above calculation is performed, see Example 6 in Appendix A. The masking value for 1/3 octave band analysis is LT,1/3oct, and the calculation is performed as follows: Step 1: Lowest 1/3 octave band n-1
Lr1.1/30et = LN1.1/30et
Step n: (n>1)
Ln.1/30ct =max (LN.1/30t; LIv-1,1/30et —2.5dB) from n=1,2,.·,22.
8 Design criteria for auditory signals of dangerous situations
When designing auditory signals of dangerous situations, the following criteria should be observed: 8.1 Sound level
The A-weighted sound level of the auditory signal of dangerous situations is equal to or greater than 65dB, and it can be identified when it exceeds the sound level of the ambient noise by more than 15dB. If the frequency characteristics or instantaneous distribution of the auditory signal of dangerous situations are obviously different from the corresponding characteristics of the ambient noise, the auditory signal of dangerous situations with a lower sound level can also be accurately and reliably identified (see 5.2.1) and can also be used. When determining the sound level of the auditory signal of dangerous situations, in addition to making it easy to identify, it is also necessary to avoid a sharp increase in the sound level in an instant (such as an increase of more than 30dIB within 0.5s), otherwise it will cause panic. If the A-weighted sound level of the ambient noise in the signal receiving area is greater than 110dB, the auditory signal of dangerous situations cannot be used alone, but other signals, such as visual signals of dangerous situations, must be added.
8.2 Frequency
The frequency of the danger auditory signal is generally in the range of 300 to 3000Hz. Compared with the ambient noise, the greater the difference in the center frequency of the octave band with the largest sound pressure level of the danger auditory signal, the easier it is to identify. When the frequency of the danger auditory signal is lower than 1500Hz, it should have sufficient sound level to meet the needs of people with hearing loss and wearing ear protectors.
8.3 Transient characteristics
8.3.1 Transient distribution of sound level
Under normal circumstances, the pulse danger auditory signal is better than the steady-state danger auditory signal. The pulse repetition frequency should be in the range of 0.2~~5Hz. Compared with the periodically changing ambient noise in the signal receiving area, the pulse repetition frequency and pulse width of the danger auditory signal cannot be the same.
The emergency evacuation auditory signal is a special danger auditory signal. Its sound level instantaneous diagram 1 is as follows. The instantaneous diagrams of all other danger auditory signals must be significantly different from it.
Instantaneous graph of sound level of emergency evacuation auditory signal
a=0.50±10%s on;
b=0.50±10%s off;
c=1. 50±10%s off,
8.3.2 Instantaneous distribution of frequency
Full period=4.00±10%s
Time. s
Danger auditory signals whose tone changes with time are also applicable (such as: high-frequency sound, or a series of sounds with different tones). 8.4 Duration of danger auditory signal
In general, the duration of danger auditory signal should be equal to the duration of danger. In certain situations, such as when the ambient noise changes briefly, temporary masking of the danger auditory signal is allowed, but it must be ensured that the masking time after the danger auditory signal begins shall not exceed 1s, and the danger auditory signal lasts at least 2s, in accordance with the requirements of 5.1 and 5.2. The instantaneous characteristics of the danger auditory signal depend on the duration and type of the danger. 8.5 Sound level requirements for the source of the danger auditory signal The product manual of the danger auditory signal source should give the following data: a. The maximum and minimum values of the A-weighted sound power level (Lw.A); or the A-weighted sound level (Ls.A.lm) measured at 1m in the main radiation direction of the sound source in the free sound field;
b. The maximum value of the octave band sound pressure level (Ls.o1.1m) at 1m in the main radiation direction of the sound source. Adoption instructions:
1 The original international standard ISO7731 did not give the instantaneous diagram of the emergency evacuation auditory signal. This figure is quoted from ISO8201 "Acoustics - Emergency Evacuation Auditory Signal". 30
GB 1251.1 --89
Appendix A
Examples of Application of Warning Auditory Signal
(Reference)
In this part, the solid line represents the signal spectrum, the dashed line represents the ambient noise spectrum, and the dotted line represents the masking threshold. Example 1 Auditory signal of danger when approaching a reciprocating conveyor Environmental noise in the signal receiving area: Axial flow fan with acoustic damping Characteristics of environmental noise: Does not change with time
Ambient noise level: LN,A78dB
Selected auditory signal of danger: Ls,A=84dB Characteristics of auditory signal of danger: The on-off time of the intermittent signal excited by electroacoustics is about 1s. 90
50010002000
40008000
Octave center frequency f,H2-
Figure A1 Octave analysis of environmental noise, masking signal and dangerous auditory signalAs can be seen from Figure A1, although in terms of A-weighted sound level parameters, the dangerous auditory signal is less than 15dB greater than the environmental noise (only 6dB), there are obvious differences between the two parameters in terms of frequency spectrum and instantaneous distribution. Moreover, within the frequency band with better audibility, there is an octave signal that exceeds the masking signal by more than 10dB, so the dangerous auditory signal is easy to identify. Example 2 represents the dangerous auditory signal when the rolling mill is short of oil. Ambient noise in the signal receiving area: noise of heat treatment furnace, rolling mill, descaling with compressed air. Characteristics of ambient noise: no change over time. Ambient noise level: LN, A = 91 dB
Selected dangerous auditory signal: Ls.A = 100 dB. Characteristics of dangerous auditory signal: continuous whistle, no similar signal in the receiving area. 31
GB 1251.1--89
LN,oer
Octave center frequency f, Hz—
40008000
Figure A2 Octave analysis of ambient noise and dangerous auditory signal. As can be seen from Figure A2, the masked spectrum is equal to the ambient noise spectrum. Although the A-weighted sound level of the dangerous auditory signal does not exceed the ambient noise by 15dB, the octave band sound pressure level of the dangerous auditory signal exceeds the ambient noise octave band sound pressure level by more than 10dB (up to 15dB) within the octave band, and there is no similar signal in the receiving area, so the signal is easy to identify. Example 3 shows the ambient noise in the receiving area of the dangerous auditory signal when approaching the gantry crane:
Chassis running noise: LN1.A—54dB
Hoisting noise: LN2.A=74dB
Noise characteristics; Both items change with time, so the A-weighted sound level and the octave band sound pressure level are weighted with "slow" time, and the maximum value is measured. Selected dangerous auditory signal: Ls.A.sx=90dB Characteristics of dangerous auditory signal: low repetition frequency bell signal 90
LN2,
10002000
Octave center frequency.Hz
Figure A3 Octave analysis of chassis walking and lifting noise, masking threshold and dangerous auditory signal Figure 32
GB 1251.1—89
It can be seen from Figure A3 that the dangerous auditory signal exceeds the A-weighted sound level of ambient noise by 15dB, and the center frequencies of the maximum octave band sound pressure levels of the two are quite different, so the signal is easy to identify. Example 4: Dangerous situation auditory signal used for conveyor site. Characteristics of environmental noise: only slight changes during operation. Environmental noise level in signal receiving area (driver's cab): LN,A=59dB. Selected dangerous situation auditory signal: Ls,A=80dB. Characteristics of dangerous situation auditory signal: high repetition frequency electric bell. 80
10002000
40008000
Octave center frequency f, Hz
Figure A4: Octave analysis of environmental noise and dangerous situation auditory signal. It can be seen from Figure A4 that the masking valve spectrum is equal to the environmental noise spectrum, and the A-weighted sound level of the dangerous situation auditory signal is more than 15dB greater than the A-weighted sound level of the environmental noise (up to 21dB). Moreover, the center frequencies of the maximum sound pressure levels in the octave bands of the two are quite different, and their instantaneous distributions are also different, so the signal is easy to identify.
Example 5: Indicating the danger auditory signal approaching the track bed cleaning equipment in the factory. Environmental noise in the signal receiving area: LN.A-94dB Selected danger auditory signal: Ls.A=100dB Characteristics of danger auditory signal: Horn signal, base frequency is 250Hz, each pulse duration is about 2s. 33
GB 1251.1---89
1000200040008000
Octave center frequency in, Hz
Figure A5 Octave analysis of environmental noise, masking and dangerous auditory signals As can be seen from Figure A5, the spectrum and instantaneous distribution of dangerous auditory signals and environmental noise are obviously different; in two octaves, the signal octave band sound pressure level exceeds the masking by more than 10dB, so the signal is easy to identify. Example 6 Based on Example 5, the personnel in the signal receiving area wear ear protectors. When wearing ear protectors, it is recommended to verify whether the dangerous auditory signal meets the requirements of 5.2 by doing a listening test. This method is better than the calculation method; when the spectrum of the dangerous auditory signal and the environmental noise is known, the calculation method is used to select the ear protector model to obtain the required sound attenuation value.
The ear protector shown in Table A1 is a high-attenuation earplug, which is used under the conditions given in Example 5. Table A1 gives the average attenuation value dj.
Earplug average attenuation value table
Calculate the actual octave band sound pressure level when wearing ear protectors and plot it in Figure A6. 34
GB 1251.1—89
10002000
Octave band center frequency .Hz—
Figure A6 Example 5 (upper part) and actual octave band analysis diagram when wearing ear protectors (lower part) 1 Effective octave band sound pressure level after calculation of ambient noise (LN.ot.jd,) in dB; L's.ori---—Effective octave band sound pressure level after calculation of hazardous auditory signal (Ls.oet.vd,) in dB; retbZxz.net
Octave band sound pressure level of masking threshold when wearing ear protectors. As shown in Figure A6, the two-emotion auditory signal L's.ct exceeds the masking threshold by more than 10dB in the 2000Hz octave band, so it is easy to identify the signal even when wearing ear defenders.
Additional Notes:
This standard was proposed by the China Institute of Standardization and Information Classification and Coding. This standard was drafted by the China Institute of Standardization and Information Classification and Coding and the Coal Science Research Institute. The main drafters of this standard are Zhang Mingxu, Feng Baochang, and Wang Yunqiu. 35
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