Private cinemas are dedicated to creating different viewing modes. In addition to privacy and comfort, the stunning audiovisual effects are one of the goals pursued by many consumers, so acoustic design is a top priority for private cinemas. Sucking less sound, what is the suction volume of each frequency band... These are best achieved by measuring and calculating the original room and combining the experimental data of various sound absorbing materials to achieve the best room. Acoustic characteristics.
First, the acoustic index
Reverberation time (T20) design expected parameters should be consistent, to ensure that the overall sound field in the room meets the standard, the difference between 125Hz~8000Hz reverberation time should not be greater than 0.05S, to ensure that the room frequency response curve is straight, and the standing wave point below 500Hz is less than two. Can not be too much, must ensure that its position is in front of the seat area, 1.5S outside the side, 2S behind the rear, to avoid obvious standing wave interference.
Second, what is the resonance phenomenon?
There are two main points in acoustic processing, reverberation and reverberation time. Reverberation time is an important criterion for the sound quality of the projection room. Reverberation time has an important effect on human hearing. It is still one of the most important reference indicators for describing indoor sound quality. The reverberation time depends on the building structure of the room, the top structure, the wall materials and the decoration, etc. The seating arrangement and other indoor installations will be affected.
The three-dimensional size of the room, the length, width and height have three basic natural resonant frequencies and three fundamental natural resonant frequencies, which are integer multiples of harmonics. These sound waves interfere with each other when they propagate in the room, resulting in a complicated combined resonant frequency. The room can be regarded as a resonator. When the frequency of the sound source is the same as the resonant frequency of the shareholder determined by the three-dimensional size of the room, a standing wave will be generated and resonance will occur. This is the phenomenon of acoustic resonance.
Sound field uniformity, acoustic dyeing, and frequency irregularity in the projection room are all related to acoustic resonance. This resonance will add the color of the room acoustic resonance to the original signal, resulting in sound dyeing, which is generally expressed in a certain section or section of the middle and low frequencies. The frequency loudness is over-enhanced, and the acoustic processing is to make a reasonable layout under the original three-dimensional size of the room. Use appropriate sound absorbing materials to increase the damping of the interface of the wall, floor, ceiling, etc., so that the intensity of the resonance of a certain frequency band is weakened. Resonance peaks are flattened to reduce the effect of unwanted resonance on the overall sound.
Third, what is the spread of sound
Many sounds are irregularly reflected, refracted, and diffracted in different directions, making the sound in the room uniform, which is the sound diffusion. Sound diffusion can improve the distribution of indoor sound field, shorten the acoustic range of front and rear rows, eliminate echo suppression feedback, etc. The purpose of using sound diffuser is to supplement the lack of a certain sound frequency band in the projection room by using a specific material diffuser to achieve a balanced state. .
However, it is also necessary to pay attention to the choice of diffuser. The diffuser cannot be a sound absorber at the same time. It is best to use some materials that are more important and made of steel, such as concrete, plastered masonry, marble, granite, etc. Choose solid wood, teak, oak, pear wood.
If the thin-walled hollow body is used, it will form a strong absorption of low frequency, and the effect will be greatly reduced. Try to avoid the use of gypsum casting. Although the production cost is low, it will produce metallic sounding, which is unfavorable to the sound.
Fourth, what is standing wave
A wave formed by superimposing two columns of waves whose frequency and amplitude are the same, the direction of vibration is the same, and the direction of propagation is opposite. This is the standing wave. When the wave propagates in the medium, its waveform is constantly changing forward. This kind of wave is called a traveling wave. The upper two waves are superimposed and then do not advance forward. This is called standing wave.
In a regular screening room, if you don't do any acoustic design, the sounds we hear during the sound of the house are not only the sound of the sound but also the sound of the sound. There is also the homophonic sound formed by the standing wave, so we always recommend the owner. The low frequency standing wave of the small room determines the overall sound of the low frequency. Only by reducing the influence of the low frequency standing wave can the low frequency effect be improved, and the standing wave phenomenon in the room is aimed at the low frequency.
5. What is blackout and soundproofing?
In fact, the shading soundproofing is mainly for home theaters, because there are many windows in the home, but there are basically no windows in the private theater. If the windows in your store are relatively small, you can ignore them. If there are windows, it is better to add some shades and soundproofing around the windows. Or other acoustic materials.
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