As a theater room, what conditions do we need to meet to be a good acoustic environment?

1. Wall treatment

Generally speaking, most of our four walls are brick walls. This kind of wall has strong reflections of high, medium and low frequencies, especially high frequencies. Therefore, "proper" sound absorption becomes the first priority. The so-called appropriateness means not to go too far. If the sound is dried up and has no charm, it will be counterproductive.

How to deal with side walls

How should these four walls be properly vacuumed? Let’s talk about the two side walls first. What we have to deal with here is the first reflected sound from the speaker. Why absorb the first reflected sound? If the first reflected sound is too much, the positioning will be unclear and the sound will sound too loud. So be sure to suck it.

How to smoke? You don't have to cover the entire wall, just about halfway between the speakers and your listening position. Approximately how large is the sound-absorbing area? It should be at least 1-1.5 meters wide and two-thirds of the height of the wall.

Common sound-absorbing materials include mineral wool, glass wool, and polyester sound-absorbing cotton. Polyester sound-absorbing cotton is better and can be made into a soft package. However, please note that do not think that nailing wooden boards can absorb sound. The wooden planks have a flat surface, no different from the original wall. The board itself is very hard and is no different from the wall. It will not absorb sound.

Treatment of the rear wall of the speaker

The rear wall of the speaker must be strong and hard, so as not to absorb the low frequencies and double the power of the amplifier. If you nail a cavity in the wall behind the speaker, no matter how thick the board or thin board you use, it will definitely have a negative impact and no positive effect. The most common negative impact is that the sound is weak, the low frequency is not strong enough, and the low frequency is not clean.

Huh? Since the wall behind the speaker needs to be strong and hard, why did you just say that it needs to be sucked? What I mean by suction is not that you make a cavity, but that you suction like a side wall. Please note that if you already feel that the positioning is accurate and the sound is not noisy after doing sound absorption on the two side walls, then there is no need to do sound absorption on the rear wall of the speaker. On the other hand, if you still feel that the sound is too loud and the positioning is not accurate, then you need to do sound-absorbing treatment on the wall behind the speaker. After the back wall is sucked, the sound is guaranteed to change.

Processing of the corner behind the speaker

Any corner is where the standing wave is strongest. If it can be treated a little, it will definitely help the sound. If left untreated, it will not cause huge harm. The most natural and cost-effective solution is to design the corner into a bookshelf, CD rack or decoration rack. Someone would board up that right angle so that it becomes a bevel instead of a right angle. This is useful, but still runs the risk of the angled cavity absorbing low frequencies. Some people make that right angle into an arc, and the arc has the effect of diffusing sound waves. However, there is still a risk of the cavity absorbing low frequencies.

What should I do with the back wall of the listening position?

Maybe you will say, I have already sat against the back wall, what else can I do with this wall? To be honest, sitting against the back wall is the worst, because the sound will be muddy at this time. Unless your system is low-frequency deficient, it must be boosted by moving closer to the rear wall. Generally speaking, your seat should be at least half a meter away from the back wall so that the sound will be cleaner.

The wall behind the listening position can actually absorb or diffuse. If you use suction, you are afraid that if you are too close to the back wall, the reflected sound will be too strong. Diffusion is used because it is far away from the back wall, and diffusion can make the sound more natural. The best way is to use sound-absorbing materials on a diffusion-shaped surface. In this way, the benefits of absorption and diffusion are obtained, which is the most perfect.

2. Ceiling and Floor Treatment

Floor Layout

Home floors are probably marble, ceramic tiles or wooden floors. In order to reduce the low frequencies reflected from the floor, we still need to lay a thick movable carpet on the ground between the speaker and the listening position. Please note that I said thick rugs, not the typical South Asian thin rugs. Why do you need thick carpet? Because thick carpets only have enough sound-absorbing effect, if you only want to use a small piece of thin carpet, it will only have a decorative effect without substantial sound-absorbing effect.

Ceiling treatment

Generally speaking, it is best for the ceiling to have both sound absorption and diffusion, so that the sound will be the best.

If there is only diffusion, the high-frequency reflected sound from the ceiling will be too strong. There are several ways to deal with ceilings:

1. Light steel frame plus mineral fiber board

This is the simplest ceiling treatment and the most economical one. Although this kind of ceiling only absorbs high frequencies without any diffusion function, it is effective in suppressing excessively noisy high frequencies and excessively long indoor echoes.

2. Caisson plus sound absorption in the central area

The so-called caisson is a ceiling that is drawn upward layer by layer. This treatment can often be seen on the ceilings of old Chinese buildings, in Shanghai and Beijing. Concert halls all do this. The diffusion function of the caisson lies in the layers of retracted steps, and its absorption function is placed in the middle piece. What are the disadvantages of caissons? First, hiring a carpenter to do it is quite expensive. Second, the cavity of the caisson itself will absorb medium and low frequencies. However, if your sound absorption and diffusion are not enough, and you also like the beauty of caissons, caissons may still be a good choice.

3. Perforated board and Gapoli diffusion board

Perforated board is the kind of thin plate full of small holes that can be bought in building materials stores. Cut the perforated board into a two-foot square piece, then cover the upward side of the perforated board with foam or sound-absorbing cotton, and then place them on the light steel frame. Just put half of the perforated board on the entire ceiling, and use the poly diffuser board on the remaining half of the light steel frame. In this way, the perforated board can absorb sound, the Poly diffusion board can diffuse it, and the entire ceiling will not look ugly when combined.