First, the characteristics of entertainment venues
Acoustic design and sound quality processing of entertainment venues are fundamental measures to ensure that the electroacoustic system can play its acoustic effects well. Sound quality design first considers environmental protection requirements, and secondly considers sound quality processing. Therefore, the sound quality design must refer to the national standards: (1) Urban Area Environmental Noise Standard (GB3096-82); (2) Civil Building Sound Insulation Design Specification (GBJ118-88); (3) Acoustic Characteristics Index of Entertainment Sound Reinforcement System And measurement method (WH0301-93). These three standards stipulate the classification of the dance hall, the allowable noise level of the entertainment venue, etc., and make recommendations on the sound quality processing and reverberation time of the entertainment venue, and can be appropriately adjusted according to the specific circumstances.
The biggest difference between the sound field of entertainment venues and concert halls and theaters is: (1) all the larger dance floor of the casino; (2) the ceilings above the dance floor are concentrated with various lamps, sound and video equipment; (3) The dance floor and the stage are often in the same space; (4) there are other noises in the entertainment venue besides singing.
Second, vibration reduction and noise reduction
In order to ensure a low noise level in the outdoor, sound insulation and vibration reduction methods are usually adopted. Commonly used sound insulation components include soundproof doors and sound insulation windows, etc., requiring higher sound insulation ceilings and floating foot floors. It should be noted that the door and window gap is the main way of sound transmission and must be handled carefully. In order to improve the sound insulation, double-layer doors and double-layer windows can be used, and the middle and the periphery of the double-layer windows should be treated with sound absorption. There should be no interference between the KTV boxes in the dance hall, including the ceiling and partition walls should have a sound insulation capacity of 50 dB. In addition, the stage speaker should be protected from vibration, and the hanging speaker bracket should also be firm and not vibrating, otherwise the speaker will be distorted.
Third, the equalization of frequency response in the hall
It is necessary to improve the sound quality structure in the hall from the perspective of architectural acoustics, but the cost is high and is often limited by environmental conditions. Therefore, some sound quality defects in the hall need to be corrected by using electro-acoustic technology, such as equalizing the frequency response with an equalizer, or using the artificial reverberation technology to change the reverberation effect in the hall, and using the digital sound field processor to simulate the concert hall and theater. Sound effects such as stadiums.
1. The role of equalization processing
Because the standing wave generated by the resonance in the hall has a peak at some frequencies, and the valley appears at other frequencies, the unevenness of the transmission response is large and complicated, and it is difficult to control. This kind of acoustic dyeing in the hall is difficult to eliminate, and can only be properly balanced to minimize his harm. Before performing the equalization process, it is important to understand the acoustic characteristics of the room and not rely solely on hearing and experience. Conditionally, the real-time spectrum analyzer can be used to use pink noise as the sound source to measure the frequency response characteristics of the main listening area, and then equalize the path to obtain a flat equalization effect as much as possible.
The frequency equalizer can also equalize the frequency distortion caused by the uneven acoustic resonance characteristics in the hall, can suppress the acoustic feedback, improve the sound quality, and can also be used in the sound art creation to express the sound color of the instrument or the actor, and improve the sound art. The overall effect. The room equalizer is used to correct the frequency response, and the narrowband filtering method is commonly used to divide the audio range into a plurality of narrow correction bands, and respectively perform lifting or attenuation processing to obtain desired uniformity. Commonly used correction frequency bands are divided into octave bandwidth and one-third octave bandwidth, and the latter has better balance effect. The octave bandwidth has twice the center frequency of two adjacent bands, such as 63 Hz, 125 Hz, 500 Hz, 1000 Hz, 2 000 Hz, 4 000 Hz and 8 000 Hz. The one-third octave bandwidth is to insert two center frequencies at a certain ratio between the two center frequencies to achieve a more accurate equalization process. The sequence of the center frequency is 63 Hz, 100 Hz, 125 Hz, 160 Hz, 200 Hz, 250 Hz, 315 Hz, 400 Hz, 500 Hz, 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, etc. The curve obtained by octave bandwidth correction is rough, but it is easy to operate and easy to use. The curve obtained by one-third octave bandwidth correction is fine, but the operation is complicated, and it must be monitored by real-time spectrum analyzer to achieve equalization processing. Otherwise it will not achieve the expected results.
2, the adjustment of the equalizer notes
(1) The equalization characteristics should be good. When the equalizers are boosted or attenuated by the same decibel number, the combined frequency characteristics should be uniform.
(2) The phase distortion of the equalizer should be small, and the phase shift characteristic of the general single-section filter should be controlled to be less than 450.
(3) The dynamic range should be wide and the nonlinear distortion should be small.
(4) The operation is simple to use, and the push-pull attenuator is relatively intuitive. When adjusting, the curve shape composed by the position of the adjustment button is approximated to the equilibrium characteristic curve.
(5) The boosting or attenuation of each calibration center frequency should not be too large, and is usually designed to be ±10 dB.
3. Balanced operation steps
(1) For a two-channel system, the equalizer must have at least two-way one-third octave bandwidth equalization.
(2) The calibration must be carried out in conjunction with a real-time analyzer. In the equalization process, the appropriate listening area must be calibrated, the reference listening point and the measuring microphone position should be selected, and the speaker wiring of the uncorrelated path should be disconnected, leaving only one prediction path to avoid testing the path of the signal crosstalk measurement, so as to correct the path to be tested. Do not count the sound pressure level.
(3) The noise generator for the sound source or the CD or VCD disc with pink noise recorded during the test, and the pink noise signal is continuously played by the A-B repeat key, and 3 to 5 measured values ​​are picked up by the microphone of the test point. The reading is stored in the memory, and then the average value is obtained; the average value of the other 2 to 4 test points is obtained by the same method, and the reference sound pressure levels of the respective points are different by less than ±6 dB.
(4) Calculate the transmission response curve with a real-time spectrum analyzer to find out the frequency bands of the peaks and valleys and their average and baseline differences. In general, the frequency range that needs to be balanced is mainly at 100-2 000 Hz, so that the transmission response unevenness is kept between ±ldB or ±2dB, and the equalization correction amount should not be too large, because the compensation exceeds 6dB, regardless of the power. Both the amplifier and the speaker system can cause distortion and overload.
(5) After the initial equalization process, the transmission response curve is re-measured, and then the appropriate equalization is given, which is repeated several times until the repeatability of the test result is good.
In listening, there are three aspects that can easily cause fatigue:
First, the sensory fatigue caused by the 80~150Hz frequency band. When the excessive low-frequency sound wavelength time acts on the human body, it will gradually feel the discomfort of the head weight, chest tightness, etc., which is prone to irritability;
The second is the auditory fatigue caused by the 3~4kHz frequency band. If the sound loudness of this frequency band is large, there will be a feeling of “fried earâ€, which will cause people to feel pain;
The third is a screaming sound produced by the 6.8 kHz band. Therefore, in the loudness playback, attention should be paid to the following aspects in terms of frequency response characteristics:
(1) The bass part with the frequency in the range of 80~50Hz cannot be a continuous sound type. It can only be a short hit type; otherwise, there will be a long time noise, which is not suitable for loud loudness playback.
(2) The high-pitched voice cannot be screamed. The crisp and pleasing sound is good, but if it sounds 120dB, it is unbearable. The source of the whistling sound is usually concentrated at 6.8 kHz, so the attenuation of this band can reduce the screaming of the source. In some entertainment venues, in order to produce the "bombing" hard effect, the 3.4 kHz band is often upgraded, so that the hearing is more fatigue-prone, and this effect is not suitable for long-time playback.
(3) The frequency band around 800 Hz often gives a feeling of noisy and narrow, and attenuating this frequency band can effectively improve the music playing effect.
The sound at the 80Hz frequency band gives a powerful and powerful stimulating effect. The rhythm sound of Disco music often produces a strong dynamic effect in this frequency band, but it is easy to form a turbid sound when you pay little attention or a little excess, especially when Intermodulation distortion is caused when the woofer is over-frequency too much. The method to avoid is to take a narrow enough segment for the lower frequency and use a single power amplifier system for playback. The playback power is generally only 25~125Hz.
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