KTV sound reinforcement standard of song and dance hall

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1. Main contents and scope of application

This standard specifies the acoustic characteristic index and measurement method of sound reinforcement system in commercial song and dance halls

This standard is applicable to all kinds of concert halls, dance halls, karaoke halls and halls with similar functions

2. Reference standard

Gb3241 1 / 1 and 1 / 3 octave filters for sound and vibration analysis

Gb3661 specification for testing condenser microphone

Electrical and acoustic performance and measurement method of gb3785 sound level meter

Gb3947 acoustic terms

Gb4959 measurement method for sound reinforcement characteristics of halls

Acoustic characteristic index of gyj25 hall sound reinforcement system

3. Terminology

3.1 sound reinforcement system

The loudspeaker that converts electrical signal into acoustic signal and the acoustic environment of Xinzhong area.

3.2 vacant auditoria

There are no spectators and actors in the hall except for the necessary measurement technicians. During the measurement, the setting in the hall is exactly the same as that in the corresponding full room normal use

3.3 maximum sound pressure level

The maximum sound pressure level of the empty field in the hall in steady state.

3.4 maximum available gain

The gain of the amplifying system in the critical state of sound feedback self excitation minus 6dB

3.5 acoustic feedback

The howling or fading sound caused by the feedback of part of the output energy from the loudspeaker to the microphone

3.6 transmission frequency characteristic

The amplitude frequency response of the average value of steady-state sound pressure level at each measuring point in the hall to the sound pressure at the microphone of the sound reinforcement system or the input voltage of the sound reinforcement equipment.

3.7 transmission gain

When the sound reinforcement system reaches the maximum available gain, the difference between the average steady-state sound pressure level at each measuring point in the hall and the sound pressure level at the microphone of the sound reinforcement system.

3.8 sound field normality

When there is sound reinforcement, the difference between the maximum and minimum steady-state sound pressure level obtained at each measuring point in the singing and dancing hall is expressed in decibels

3.9 background noise

When the sound reinforcement system is not working, the average value of indoor background noise sound pressure level at each measuring point in the hall

3.10 total noise

The average value of noise sound pressure level at each measuring point in the hall when the sound reinforcement system reaches the maximum available gain but no useful sound signal is input.

3.11 system distortion

The nonlinear distortion of sound reinforcement system in the whole process from input sound signal to output sound signal. Note: when it is difficult to measure the nonlinear distortion from acoustic input to acoustic output, it is allowed to measure the nonlinear distortion from electrical input to acoustic output as system distortion, but it should be noted. Generally, harmonic distortion is used to measure system distortion approximately.

3.12 reverberation time

The time required for the sound source to reach the steady state and the indoor sound pressure level to be attenuated by 60dB after the sound is stopped.

4. Acoustic characteristic index of sound reinforcement system in song and dance hall

Standards and regulations (acoustic characteristic index and measurement method of sound reinforcement system in song and dance hall)

Cultural industry standards of the people's Republic of China

4.1 the acoustic characteristic indexes of the sound reinforcement system of the singing hall and karaoke hall are divided into level 1 and level 2,

Acoustic characteristics

Level maximum sound pressure level (DB) transmission frequency characteristic sound transmission gain sound field nonuniformity total noise level dB 〈 a 〉 distortion

The average sound pressure level of 100 ~ 6300hz ≥ 103db40 ~ 12500hz is 0dB at 80 ~ 8000Hz, and it is allowed to be + 4 ~ - 8dB, and it is allowed to be ≤ 4dB at 80 ~ 8000Hz. The average sound pressure level of 125 ~ 4000Hz is ≥ - 6dB, 100Hz ≤ 10db1000hz ≤ 8db63000hz ≤ 8dB, 35.5%

Level 2 (Level 1) karaoke hall ＞ 125 ~ 4000Hz ≥ 98db63 ~ 8000Hz, with the average sound pressure level of 125 ~ 4000Hz as 0dB, + 4 ~ - 10dB is allowed, and the average value of ≤ + 4db125 ~ 4000Hz ≥ - 6db1000hz ≤ 8db4000hz ≤ 8db40 10% is allowed within 125 ~ 4000Hz

Level 2 karaoke Hall (karaoke room) > 250 ~ 4000Hz ≥ 93db100 ~ 6300hz, with the average sound pressure level of 250 ~ 4000Hz as 0dB, + 4 ~ - 10dB is allowed, and within 250 ~ 4000Hz, ≤ + 4 ~ - 6dB, ≥ - 10db1000hz ≤ 12db4000hz ≤ 12dB, karaoke room is not assessed by 40.13%

4.1 the acoustic characteristic indexes of the sound reinforcement system of the singing hall and karaoke hall are divided into level 1 and level 2,

Acoustic characteristics

Level maximum sound pressure level (DB) transmission frequency characteristic sound transmission gain sound field nonuniformity total noise level dB (a) distortion

Class I 100 ~ 6300hz ≥ 103dB

The average sound pressure level of 40 ~ 12500hz is 0dB at 80 ~ 8000Hz, which is allowed to be + 4 ~ - 10dB, and the average value of ≤ 4db125 ~ 4000Hz is allowed to be ≥ - 8db100hz ≤ 10db1000hz ≤ 8db6300hz ≤ 8db407% at 80 ~ 8000Hz

The average sound pressure level of secondary 125 ~ 4000Hz ≥ 98db63 ~ 8000Hz is 0dB at 125 ~ 4000Hz, + 4 ~ - 10dB is allowed, and ≤ 4dB is allowed within 125 ~ 4000Hz. The average value of 125 ~ 4000Hz ≥ - 10db1000hz ≤ 8db4000hz ≤ 8db40 10%

Class III 250 ~ 4000Hz ≥ 93dB, 100 ~ 6300hz, the average sound pressure level of 250 ~ 4000Hz is 0dB, the allowable + 4 ~ - 10dB, and the allowable + 4 ~ - 6dB within 250 ~ 4000Hz, the average value of 250 ~ 4000Hz ≥ - 10db1000hz ≤ 8db4000hz ≤ 8dB 4513%

Note: the non-uniformity of the sound field of the first-class song and dance hall shall be assessed separately for the dance floor and seats.

2、 Except for the noise, all the indexes of the sound field of the third level song and dance hall are only tested on the dance floor.

4.1 the characteristic index of sound reinforcement system of disco is level 1 and level 2

Acoustic characteristics

Level maximum sound pressure level (DB) transmission frequency characteristic sound transmission gain sound field nonuniformity total noise level dB (a) distortion

Level 1: 100 ~ 6300hz ≥ 110dB, 40 ~ 12500hz: the average sound pressure level of 80 ~ 8000Hz is 0dB, and the average value of ≤ 4db125 ~ 4000Hz is allowed within 80 ~ 8000Hz ≥ - 8db100hz ≤ 10db1000hz ≤ 8db6300hz ≤ 8dB 407%

The average sound pressure level of 125 ~ 4000Hz is 0dB, and it is allowed to be + 4 ~ - 10dB, and it is allowed to be ≤ 4dB within 125 ~ 4000Hz. The average value of 125 ~ 4000Hz is ≥ - 10db1000hz ≤ 8db4000hz ≤ 8db45 10%

Note:

① The sound pressure level of sound reinforcement system in song and dance hall should be below 9-b in normal use, and the maximum sound pressure level in a short time should be controlled within 110dB

② The acoustic performance index of sound reinforcement system in disco is only evaluated on the dance floor

4.4 General requirements for architectural acoustics of song and dance halls

Acoustic design should be carried out in the process of new construction or reconstruction of song and dance hall

4.4.1 appropriate loudness, uniformity, clarity and fullness are required in the auditorium. Echo, vibrating echo and sound focusing and other defects are not allowed in the singing and dancing hall

4.4.2 see Appendix A for reverberation (T60) of song and dance hall

4.4.3 impact on external environment

In normal working days, the influence of sound reinforcement system on the outside world should meet the standard requirements of environmental protection department, and the average value of short-time music climax is allowed to exceed the standard by 15dB

5. Measurement method

5.1 measurement conditions

5.1.1 before measurement, the sound reinforcement equipment shall be installed in the hall according to the design requirements, and the sound reinforcement system shall be adjusted to make it work normally.

Note: if there is a system equalizer, it should be adjusted to the best system compensation before measurement.

When the 5.1.2 is measured, the multi frequency compensation of the mixer in the sound reinforcement system is placed in the "straight" position, and the tone compensation of the power amplifier is placed in the normal position.

5.1.3 during the measurement, the sound pressure level of the measuring points in the hall shall be at least 15 dB higher than that in the hall. When the reverberation time is measured, the signal-to-noise ratio should meet the requirement of 35dB at least. 5.1.4 each measurement is generally carried out in the open field.

5.1.5 all measuring points must be 1.5m away from the wall and 1.2 ~ 1.3m from the ground. For a hall with a floor, the measuring point should include the floor area.

5.1.6 the measuring points should be evenly distributed in the hall, generally no less than 4-9 points. For symmetrical song and dance hall, the minimum requirements of measuring points in the main activity area are as follows: 4 points are measured in the hall of less than 100 square meters, and the distribution is shown in Figure 1. 6 points are measured in the hall of 100 ~ 200 square meters. The hall measuring point above 200 square meters. The measuring points should be evenly distributed on the symmetrical side.

Note: symmetry is not only architectural symmetry, but also acoustic field symmetry.

5.2 measuring instruments this standard does not exclude the use of other instruments with the same accuracy.

5.2.1 audio signal generator

5.2.1.1 frequency range: 20 ~ 20000hz ± 0.5dB

5.2.1.2 total harmonic distortion: no more than 0.3%.

5.2.2 noise signal generator

5.2.2.1 the spectral density of pink noise is z20 ~ 20000hz, and the nonuniformity at its output is ± 1.5dB

5.2.2.2 SNR shall not be lower than 60dB.

5.2.3 power amplifier

5.2.3.1 frequency range: 20 ~ 20000 Hz, nonuniformity better than ± 0.5dB

5.2.3.2 total harmonic distortion: no more than 0.5%.

5.2.3.3 rated power: not less than 50W.

5.2.4 test microphone

According to gb3661.

5.2.5 filter

According to gb3241.

5.2.6 the sound level meter shall meet the requirements of type I sound level meter in gb3785.

5.2.7 measurement amplifier

5.2.7.1 the frequency range is T20 ~ 20000hz, and the nonuniformity is better than 0.5d's a

5.2.7.2 total harmonic distortion: no more than 0.5%

5.2.8 distortion meter

5.2.8.1 frequency range: 20 ~ 20000 Hz

5.2.8.2 distortion measurement range: 0.1% ~ 10%

5.2.9 test sound source

5.2.9.1 frequency range: 100 ~ 10000hz, nonuniformity better than 6dB

5.2.9.2 total harmonic distortion: no more than 5%.

5.2.9.3 rated power: 10W 〈 sensitivity > 90dB 〉

5.2.10 reverberation time tester

5.2.10.1 frequency range: 100 ~ 8000Hz.

5.2.10.2 reverberation time test range: 0.3s ~ 10s.

5.2.11 the frequency analyzer is an instrument that can analyze the frequency spectrum of the signal in the time domain, and the filter shall meet the requirements of 5.2.5. It is required that each center frequency of the filter can be scanned automatically or manually.

5.3 measurement items

5.3.1 transmission [amplitude] frequency characteristics

5.3.1.1 the electrical input method adopts the point measurement method shown in Figure 2, and the measurement steps are as follows:

a. Turn on the test system, output 1 / 30ct pink noise signal, adjust the output of noise source to make the output of loudspeaker system meet the requirements of 5.1.3.

b. Change the center frequency of 1 / 30 CT band-pass filter and keep the level value of each frequency band constant. Measure the sound pressure level with a sound level meter or a spectrum analyzer at each measuring point in the song and dance hall.

c. The measurement is carried out in the transmission frequency range, and the test signal is selected according to the center frequency of 1 / 30 CT.

d. The measurement points shall be carried out according to 5.1.5 and 5.1.6.

Note: when using the spectrum analyzer for continuous frequency sweeping measurement, pink noise can be used as the signal source 〈 remove the filter in Figure 2 〉. The frequency spectrum can be measured at each measuring point by frequency sweeping method, and then the spectrum of pink noise can be subtracted from the spectrum of each measuring point to obtain the transmission frequency characteristics.

5.3.1.2 the point measurement method shown in Figure 3 is adopted for the measurement of acoustic input method, and the measurement steps are as follows:

a. Turn off the test sound source system and adjust the gain of the sound reinforcement system to reach the maximum available gain.

b. The distance between microphone and test sound source is 0.5m.

c. Turn on the test system, output 1 / 30ct pink noise signal, adjust the output of the noise source to make the signal-to-noise ratio of the test point greater than 15dB

d. The center frequency of L / 30ct band-pass filter is changed, and the sound pressure level is measured by sound level meter or spectrum analyzer at the microphone and at the measuring points in the singing and dancing hall.

e. It is required to keep the sound pressure constant at the microphone.

f. The measurement is carried out within the transmission frequency range, and the test signal is selected according to the center frequency of 1 / 30 CT

g. 5.1.5 and 5.1.6 for measuring points. Note: pink noise can be used as signal source (filter is removed in Fig. 3) for continuous frequency sweeping measurement with spectrum analyzer, and the noise can be measured at microphone and at each position

Then the spectrum of each measuring point is subtracted from the spectrum of the microphone to obtain the transmission frequency characteristics

5.3.2 sound transmission gain

The measurement block diagram is the same as

While measuring the transmission frequency characteristics according to 5.3.1.2, subtract the sound pressure level received by the microphone from the sound pressure level measured at each measuring point in the song and dance hall, and average the sound transmission gain according to the frequency. The center frequency of the test signal is the same as that in 5.3.1.2, and it is also allowed to be measured according to the octave center frequency.

5.3.3 maximum sound pressure level

5.3.3.1 electrical input method

The measurement block diagram is the same as Figure 2, and the measurement steps are the same as article 5.3.1.1. It is required that the voltage fed into the loudspeaker system is equal to 1 / K 〈 k = 2 ~ 10 〉 of the voltage value of the designed power 〈 or rated power 〉. In the system

The maximum sound pressure level requires that the sound pressure level of each 1 / 30ct frequency band be measured at each measuring point within the frequency range, and the total sound pressure level of the point within the transmission frequency range is calculated, and the corresponding frequency band is obtained after adding 20lgk

The maximum sound pressure level. The maximum sound pressure level of each measuring point is calculated by the following formula, where zli is the sound pressure level of the ith 1 / 30ct frequency band, and N is the number of 1 / 30ct frequency bands within the transmission frequency range

5.3.4 sound field unevenness

According to the measurement results in 5.3.1, list or plot the sound pressure level values of each center frequency at different measuring points to obtain the corresponding sound field distribution.

5.3.5 total noise

The measurement was carried out in an empty field.

During the measurement, all the equipment in the singing and dancing hall, such as ventilation, temperature control, noise generating equipment, sound reinforcement system and silicon controlled dimming system, are turned on

The measuring points are carried out according to 5.1.5 and 5.1.6

The gain control position of sound reinforcement system is the same as 5.3.1.2. The sound level meter is used to measure in the range of 63 ~ 8000Hz according to the octave bandwidth. The measurement results are drawn on the same record paper to obtain the noise spectrum of the song and dance hall. The measurement should include linear and A-weighted data

Note: when the total noise is measured, turn off the sound reinforcement system equipment, and measure according to the above steps to obtain the background noise spectrum. The A-weighted sound level is roughly the noise evaluation curve NR value plus 5, that is, the noise evaluation number NR = a sound level minus 5

5.3.6 the block diagram of system distortion measurement is shown in Figure 4.

The test signal is fed to the loudspeaker system through the voice console and power amplifier. It is required that the voltage fed into the loudspeaker system is equal to L / K 〈 k = 2 ~ 10 〉 of the voltage value of the designed power 〈 or rated power 〉. The test frequency is 500Hz, 1000Hz and 2000Hz. The sound pressure level of each frequency point and the sound pressure level of the second and third harmonics are measured by the spectrum analyzer, and the harmonic distortion value m is calculated by the following formula.

Where l is always the sound pressure level read out by the spectrometer in the linear range, L2 and L3 are the sound pressure levels of the second harmonic and the third harmonic respectively.

The measuring point should be on the center line of the speaker, 2m away from the speaker

Reverberation time

The measurement block diagram is the same as Figure 2, and the signal received by the sound level meter is fed to the reverberation time measuring instrument (or directly received and measured by the reverberation time measuring instrument).

The L / 30ct pink noise signal from the noise source is directly fed into the mixer input of the sound reinforcement system. Adjust the output of the sound reinforcement system to make the signal-to-noise ratio of the measuring point meet the requirements of 5.1.3. The measurement is carried out on the predetermined measuring points in the song and dance hall. The measurement can also be carried out with an external concentrated sound source, which should be placed near the corner of the hall

When the sound source stops making sound, the reverberation time of the frequency is measured with a reverberation time meter.

The measurement frequency should be selected at least at six points: 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz