This standard specifies the measurement method of acoustic characteristics of halls equipped with sound reinforcement equipment. This standard is applicable to the measurement of acoustic characteristics of various halls and other places equipped with sound reinforcement equipment. This standard does not exclude other measurement methods that can obtain the same accuracy. GB/T 4959-1995 Measurement method of hall sound reinforcement characteristics GB/T4959-1995 standard download decompression password: www.bzxz.net

UDC534.6:725.8
National Standard of the People's Republic of China
GB/T4959—1995
Methods of measurement for the characteristicsof sound reinforcement in auditoriaPublished on 199507-24
Implementation on 1996-03-01
State Administration of Technical Supervision
Subject content and scope of application
Referenced standards
Measurement conditions
Measuring instrument
Measurement method
Sound reinforcement characteristics
Transmission (amplitude>frequency characteristics
6.1.2 Transmission gain
Maximum sound pressure level
6.1.4 Sound field unevenness
System harmonic distortion||t t||Total noise
6.2 Architectural acoustic items related to sound reinforcement characteristics.......+......
6.2.1 Background noise
6.2.2 Time distribution of reflected sound
6.2.3 Reverberation time...
6.2.4 Regeneration mixing time
6.3 Rapid speech transmission index
6.4 Method for measuring Chinese intelligibility
National Standard of the People's Republic of China
Method for measuring hall sound reinforcement characteristics
Methods of measurement Tor the characteristicsof sound reinforcement in auditoria1 Subject content and scope of application
This standard specifies the measurement method of the acoustic characteristics of halls equipped with sound reinforcement equipment. This standard is applicable to the measurement of acoustic characteristics of various halls and other places equipped with sound reinforcement equipment. This standard does not exclude other measurement methods that can obtain equal accuracy. 2 Reference standards
GB 2019
Basic parameters and technical requirements of tape recorders 1/1 and 1/3 octave filters for sound and vibration analysis GB 3241
Technical conditions for testing condenser microphones
GB3661
Electrical and acoustic properties and test methods of sound level meters GB3785
GB6278
Analog program signals
GB 9401
Microphone measurement method
GB/T14476 RASTI method for objectively evaluating the intelligibility of speech in a hall GB/T15508-~1995 Acoustic speech clarity test method GBJ76 Specification for measuring reverberation time in halls
3 Terms
The terms used are only to explain the physical meaning of the relevant items in the standard. 3.1 Maximum available gain maximum available gain The gain when the sound reinforcement system generates feedback in the hall to which it belongs minus the critical gain of 6B. 3.2 Test sound source measuring sound source various forms of sound generators specially composed to measure the various indicators of the sound reinforcement system. 3.3 Syllable clarity syllablearticulatian The statistical average of the accuracy of the audiometer's judgment of the specified syllable voice. 3.4 Equalizer egualizcr
GB/T 4959—1995
Replaces GB4959·-85
In order to compensate for the frequency characteristics of the transmission (amplitude) of the hall sound reinforcement system, a frequency characteristic adjustment device is added. 3.5 Speech transmission index speech transmission index (STI) It is a physical quantity and represents the quality of speech transmission related to intelligibility. 3.6 Rapid speech transmission index rapid speech transmission index (RASTI) It is a simplified form of the speech transmission index method (STI method) under certain conditions, used to measure the quality of speech transmission related to intelligibility (see GB/T14476).
Approved by the State Administration of Technical Supervision on July 24, 1995, and implemented on March 1, 1996
4 Measurement conditions
GB/T 4959-1995
4.1 Before measurement, the sound reinforcement equipment must be installed in the hall according to the design requirements, and the sound reinforcement system must be adjusted to be in normal working condition. Note: Before measurement, the homogenizer (if any) needs to be adjusted for optimal system compensation: 4.2 During measurement, the tone adjuster of the mixer in the sound reinforcement system is set to the "flat" position. The tone compensation of the power amplifier (if any) is set to the normal position.
4.3 During measurement, the sound pressure level at the measuring point in the hall should be at least 15dB higher than the normal total sound level of the hall. When there is reverberation and regenerative reverberation, the signal-to-noise ratio during measurement should meet the 35dR requirement.
4.4 Each measurement should generally be carried out under empty and full conditions respectively. When it is difficult to fill the venue or simulate a full venue, an empty venue may be used. 4.5 The selection of measuring points shall meet the following conditions: 4.5.1 All measuring points shall be more than 1.5 m away from the ground and the height of the measuring point shall be 1.2 to 2.3 m. For halls with balcony below, the measuring points shall include the balcony area. For places with stage or podium sound reinforcement, the measuring points shall also include the stage area or the main podium area. 4.5.2 For symmetrical halls, the measuring points may be selected in the area on the side of the center line (including the vicinity of the center line). 4.5.2.1 The number of measuring points for transmission efficiency characteristics, transmission gain, maximum sound pressure level, system distortion and reflected sound time distribution shall be selected from the lower fifth of all seats in the venue, and shall not be less than five points at most. The distribution of measuring points should be reasonable and representative. If there is unevenness in the sound field at eight points (no building), the number of points should not be less than half the field) and then 1-2 rows should be evenly selected.
Point measurement of all seats
Select every few rows,
one-tenth. They can be near the center line, the left half (or in large venues. To reduce the measurement workload, the number of points can be appropriately reduced.
4.5.2.3 Reverberation time has risen. When the venue is empty, the reverberation time measurement should be no less than five points, and when the venue is full, no less than three points. The full-field measurement points are generally consistent with the empty-field measurement points.
4.5.2.4 Total noise. Scene noise measurement is only carried out under empty conditions. The selection of measurement points is the same as that of Article 4.5.2.3. 4.5.2.5 Measurement of door absorption and radiation time distribution during reverberation. When necessary, additional measurement points can be set on the stage. 4.5.2.6 Measurement of RASTI index can be It is carried out under empty field and full field conditions. The selection of measuring points shall be in accordance with Article 4.5.2.3. 4.5.3 For non-relevant measurements, additional measuring points shall be added. 4.6 The measurement of some items can be carried out by recording method (sound recording, playback 5 Measuring instruments
This standard does not exclude the use of other instruments with the same accuracy. 5.1 Frequency elimination signal generator
Frequency range: 20~20000 Accuracy better than 0.5dB Total harmonic distortion: not more than 0.3%
5.2 Noise signal generator
With pink noise output function.
Spectral density of pink noise (--3dB/oct): 20~20000Hz, unevenness is better than ±1 when the "attenuator output" or the load end is open. 5 dR.
20~20000Hz amplitude is Gaussian distribution.
Signal-to-noise ratio is not less than 60 cB.
5.3 Test power amplifier
Frequency range: 50-15000Hz, unevenness better than 1dB; total harmonic distortion: not more than 0.5%,
New rated power: not less than 50W;
Load impedance: 80,160.
5.4 Test capacitor microphone
According to the provisions of GB 3661.
5.5 Measurement amplifier
GB/T 4959--1995
Frequency range: 20～20000Hz, unevenness better than ±0.5dB; total harmonic distortion: no more than 0.5%;
Open circuit noise (linear), no more than 15μV: short circuit noise (linear), no more than 10μV. 5.61/3 uct bandpass filter
According to the provisions of GB 3241.
5.7 Electric semi-recorder
Frequency range: 20～20000Hz, unevenness better than ±0.5dB Dynamic range: 50dB, 75dB
Resolution: better than 0.5mm when using 100mm recording paper; better than 0.25mm when using 50mm recording paper, input impedance: 16~18k:
Writing speed: at least 100mm/s and 250mm/s 5.8 Sound level meter
According to the provisions of CR 3785.
5.9 Audio spectrum analyzer
Audio spectrum analyzer is a combination of measuring amplifier and 1/1 and 1/3 oct filters. 5.10 Oscilloscope
Long afterglow;
Maximum sweep time 10 s;
Able to observe positive and negative pulse waveforms with a repetition frequency not higher than 2000Hz, a sensitivity of 50us～10s, and an amplitude of 0.02～40V; time scale: with six gears of 0.02, 0.2, 2, 20, 200, 500ms. 5.11 Audio voltmeter
Prediction range: 20~20000Hz
Input impedance: not less than 100 kN
Input capacitance: not more than 20 pF;
Indication accuracy: better than ±2.5%;
Crest factor: not less than 5.
5.12 Recorder
According to the indicators of Class C or Class B of cassette in GB2019. These recorders should not be equipped with AVC and AGC circuit control. 5.13 Test sound source
5.13.1 Loudspeaker
Frequency range: 63~15000Hz, unevenness better than 10dB: 100~10000Hz, unevenness better than 6dB; Total harmonic distortion: not more than 5%;
Sensitivity: not less than 94 dB (1 n1,1 measurement); Rated power>10W:
Nominal impedance: 8H;
Box volume, not more than 0.1 m.
5.13.2 Pulse sound source
Pulse sound source with certain duration and waveform requirements and stable performance, such as spark sound generator. 5.14 Speech Transmission Index Meter
5.14.1 Transmitter
Test signal: irregular pink noise (including typical language spectrum in accordance with IEC268-16). 3
GB/T 4959—1995
Octave filter: 500Hz and 2000H2.
Modulation frequency, 500Hz: 1.02, 2.03, 4.07.8, 14Hz12 000 Hz, 0.73, 1.45.2. 90, 5.81, 11.63 Hz. Output, internal field sounder 500Hz at the cabinet distance 1m reference output sound level is 59dB: 20C0Hz at the cabinet distance 11 reference output city level is 5023.
5.14.2 Receiver
Input sensitivity: 30mV input produces 94dB display: Input range: 20~120dB (sinusoidal signal) RASTI input range: 500Hz octave: 29~115dB (RASTI signal) 2000 Hz octave: 25~115dB (RASTI signal);
Adjustment frequency accuracy: upper 0.1%:
Measurement period: 85, 16s, 32
Display: 1 digit 7-segment ICD
6 Measurement method
6.1 Sound reinforcement characteristics
6.1.1 Transmission C amplitude lock rate characteristics
The average value of the total sound pressure of the audience D in the hall relative to the sound pressure at the microphone of the sound reinforcement system or the amplitude-frequency response of the input terminal of the sound reinforcement equipment.
The measurement can be carried out as follows. The measurement result shall indicate which method is used. 6.1.1.1 Gram input
The measurement can be carried out by the test power amplifier (see Figure 1 and Article 2.6.2.1 of GB9401) or the comparison method (see Figure 2 and Article 2.6.2.2 of GB9401).
Speaker system
Special speaker
Normal point signal generator
Band filter
Test power car
Drum amplifier
Full sound stage
Amplifier
When measuring, 1/3oCt pink noise signal is added to the test sound source through the test power amplifier: adjust the test sound source system output to make the signal-to-noise ratio of the measuring point meet the requirements of Article 1.3. Change the center frequency of the 1/3oct bandpass filter, measure the sound pressure level at the transmitter and the measuring point in the auditorium, and take the difference.
In the comparison method, the sound pressure at the microphone can be controlled to be constant (as shown in the dotted line connection in Figure 2): or it can be not controlled to be constant (as shown in Figure 2, but without the dotted line 4
waist diagram and connection).
GB/T4959-1995
During measurement, the microphone is placed at the use point specified in the design. The directivity of the microphone is adjusted according to the design requirements and should not be affected by the test microphone in the comparison method. The distance between the test sound source and the microphone in front of the microphone is 0.5m for language sound reinforcement and 5m for music sound reinforcement. Note: When the newly specified use point in the design is unclear, the microphone can be placed at the midpoint of the stage curtain line. Available points for measurement Measurement method or automatic measurement method (see GB9401 Section 2.6.1). The measurement is carried out within the transmission frequency range, and the center frequency of the test signal is taken as 1/oc center frequency. Field detector system
Noise signal
Generator
6.1.1.2 Electrical
Measurement circuit See Figure 3.
Signal network
Noise signal
Generator
To test amplifier
Microphone
Test microphone
Tuning combination
A-band pass filter
Circuitary combinationbZxz.net
Amplifier
Test instrument
Amplifier
|Digital amplifier
Sound reinforcement system research
Recorder
Pico-level meter
1/3oct pink noise signal is directly fed into the input of the sound reinforcement system mixer. Adjust the output of the sound source so that the signal-to-noise ratio at the test point meets the requirements of Article 4.3. Change the center frequency of the 1/3oct bandpass filter, keep the level value of each frequency band constant, and measure the sound pressure level at the specified test point in the auditorium
The measurement is carried out within the transmission frequency range, and the center frequency of the test signal is the same as that specified in Article 6.1.1.1. 6.1.2 Transmission gain
When the sound reinforcement system reaches the highest available gain, the difference between the average steady-state sound pressure level at each seat in the hall and the steady-state sound source level at the sound reinforcement system speaker,
The measurement circuit is the same as Figure 1.
Subtract the pressure level at the microphone from the average sound pressure level measured at each measuring point in the auditorium, and average them according to frequency to obtain the transmission gain of the band 5
GB/T4959-1995
. If the relationship between the transmission gain value and the frequency is plotted on the same frequency coordinate paper, the transmission gain frequency characteristic can be obtained (which is also the transmission frequency characteristic of the sound input method under the condition of the highest available gain). The center frequency of the test signal is the same as that of Article 6.1.1.1, and it is also allowed to measure at multiples of the rated center frequency. Note: When adjusting the highest available gain of the sound reinforcement system, the determination of the self-excitation critical point can be based on the instrument indication and the human ear judgment. 6.1.3 Maximum sound pressure level
The highest steady-state quasi-peak sound pressure level generated by the sound reinforcement system at the auditorium. The measurement can be carried out by the following methods, and the measurement results must indicate which method is used. 6.1.3.1 Electrical input method
a. Narrowband noise method
The measurement circuit is the same as Figure 3.
Directly feed the 1/3oct (or 1/1oct) pink noise signal into the input of the sound reinforcement system mixer, adjust the noise source output, and make the input voltage of the loudspeaker system equal to the level value of one-tenth to one-fourth of the designed power. When the sound pressure level is close to 90dB, the power used can be less than one-tenth. Within the transmission frequency range of the system, measure the sound pressure level of each 1/3act or 1/1oct frequency band, and then average the maximum sound pressure level of the corresponding frequency band. Note: When the designed power is unknown, the rated power can be used for calculation. b. Broadband noise method
The measurement circuit is the same as Figure 3, except that the 1/3oct bandpass filter is replaced by the analog program signal network. During the measurement, the analog program signal after the weighting network is directly fed into the input of the sound reinforcement system mixer, and the power adjustment of the loudspeaker system is the same as in Article 6.1.3.1a. Use a sound level meter to measure at the specified measuring points in the hall, and convert the measured values. Then average. 6.1.3.2 Sound input method
a. Narrowband noise method
The measurement circuit is the same as Figure 1.
Adjust the test system so that the test sound source set on the stage emits a 1/3oct pink noise signal, which is received by the microphone and enters the sound reinforcement system. The power adjustment of the speaker system and the selection of the test frequency are the same as in Article 6.1.3.1a. Measure the sound pressure level of each 1/3oct frequency band within the transmission frequency range of the system, convert it to obtain the maximum sound pressure level of the corresponding frequency band, and then average it. During the test, the microphone position is the same as Figure I (that is, the use point specified in the design), and the test sound source is placed 0.5m in front of the microphone. b.Broadband noise method
The measurement circuit is the same as Figure 1, except that the 1/3oct bandpass filter is replaced by an analog program signal network. Adjust the test system so that the test sound source emits an analog program signal, which is received by the microphone and enters the sound reinforcement system. The power adjustment of the speaker system is the same as in Article 6.1.3.1a. The sound level meter is used to measure at the specified measuring points in the hall, and the measured values ​​are converted and then averaged to obtain the SPL. The positions of the microphone and the test sound source are the same as in Article 6.1.3.2a. Note: When measuring by this method, the output signal of the test sound source is only close to the frequency characteristics of the analog signal. 6.1.4 Sound field unevenness
The difference in steady-state sound pressure levels at different audience seats in the hall (when there is sound reinforcement). The measurement circuit is the same as Figure 1.
The measurement signal uses 1/3oct pink noise. The center frequency of the measurement signal is generally taken as the center frequency of the octave. According to the frequency band sound pressure level measured at each measuring point in different frequency bands, the corresponding sound field distribution diagram can be made. 6-1.5 System Harmonic Distortion
Harmonic distortion generated in the whole process from input sound signal to output signal of the sound reinforcement system. Note: When it is difficult to measure the nonlinear distortion from sound input to sound auxiliary output (for example, it is difficult to generate a standard measurement signal or it is unconditional to extract the direct sound signal of the sound reinforcement in the hall), the harmonic distortion from electrical input to sound output is allowed to be used as the harmonic distortion of the system (see Figure 1), but it should be noted that this is the distortion from electrical to sound.
A 1/3oct pink noise signal U with a center frequency of F is fed into the input terminal of the sound reinforcement system mixer. Adjust the gain of the sound reinforcement system so that the input voltage of the generator system is equivalent to the level value of one-tenth of the designed power. At the specified measuring point in the hall, the signal with the center frequency of F, 2F, and 3F is measured by the high-frequency spectrum analyzer of the test transmitter. The harmonic distortion coefficient is calculated by formula (1). Note: When the design power is unknown, it can be calculated according to the rated power. K
VU-? +Uie
can also be used to show the fundamental wave and third harmonic characteristics. X100%
The test frequency can be taken from 125 to 4000Hz according to the octave center frequency. 6.1.6 Total Noise Bandpass Filter The sound reinforcement system is at the highest available gain, but no useful output is produced. The average noise sound pressure level at each seat in the hall is measured under the condition that the noise level is measured. During the measurement, all noise-generating equipment in the hall, such as ventilation, temperature control, dimming and other equipment and the sound reinforcement system, are turned on, and the selection of measurement points is the same as in Article 4.5.2.3. The measurement can be calculated by taking values ​​in the range of 63~8000Hz according to the octave bandwidth. The measurement results are compared with the NR evaluation output to obtain the NR value. The measurement of the sound reinforcement system is the same as in Article 6.1.2. The measurement can be carried out according to the diagram or by automatic recording. The microphone system is the same as in Article 6.2. Architectural acoustic items related to sound reinforcement characteristics 6.2.1 Background noise Test microphone The average indoor sound pressure level at each auditorium in the hall when the sound reinforcement system is not working. When measuring the total noise in the field, turn off the sound reinforcement system equipment and measure the background noise according to the method in Article 6.1.6. 6.2.2 Time distribution of reflected sound refers to the time arrangement of the reflected sound in the room when the sound source emits a pulse sound. This is recorded in Figure 6. The measurement circuit is shown in GB/T4959--1995. The receiving frequency is 500, 1 000, and 2 000 Hz. The pulse width is 10 ms and the pulse interval is 35. The total length of the oscilloscope time scale is 500 ms during measurement. The selection of the measuring point is the same as in Article 4.5.2.3. The reflected sound graph displayed on the oscilloscope 1: can be photographed with a camera for analysis. 6.2.3 Reverberation time The time required for the average sound energy density to decay from the original value to 60 dB after the indoor sound has reached a stable state and the sound source is stopped. 1/3 of the sound energy density emitted by the noise source3 Reverberation time
Transmitter
Audio tester
Lai Puyi
Chang Zaxin
After the indoor sound has reached a stable state, the sound source is stopped, and the average sound energy density decays from the original value to -(60 dB) in time.
1/3 of the sound emitted by the noise source3 Reverberation time
Transmitter
Audio tester
Lai Puyi
Chang Zaxin
After the indoor sound has reached a stable state, the sound source is stopped, and the average sound energy density decays from the original value to -(60 dB) in time.
1/3 of the sound emitted by the noise source
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