Calculation and verification method of standing wave in audio-visual audio-visual room

For any room that has not been acoustically treated, the room size is a definite factor in determining the standing wave.
Let's take a look at a formula: 340 (m) / distance (m) / 2 = standing wave frequency
340 is the speed of sound, the distance is the distance between the walls of your room, 2 is divided by 2 because the standing wave is half-wave. Let’s take a look at the drawings of my listening room.

As you can see, the largest area of ​​a room, the largest part has three: front, back, left and right, up and down. Then according to the distance I measured, use the above formula to calculate the frequency of the most likely standing wave in my house:
Before and after: 340/4.45/2=38HZ
Left and right: 340/2.98/2=57Hz
Up and down: 340/2.5/2=68Hz

At the same time, we should also know that the standing wave will also occur at the multiplier, so
38 HZ 76 HZ 152HZ .........
57HZ 114HZ 228HZ ..........
68HZ 136HZ 272HZ ..........

Next, take a look at what was measured yesterday. I am nervous, I don’t know if I am sure. By the way, I have set the gain of all standing waves to 6dB.

This is more clearly seen, each frequency
Looked at the current temperature, 14 degrees, yesterday should be the same as today
The effect of temperature can be ruled out.
This test result actually made me very uncomfortable.
Because the decoration of my audio-visual room paid attention to the high-frequency sound absorption (I asked for the quotation room, the vocal recording is the main, so people may not deal with the low frequency), and the control of the reverberation time. At present, Tsukuba is not effectively controlled, and it is quite powerful. The measurement results can also be seen, there is at least a gap of plus or minus 10 decibels, so in order to become a perfect space, this listening room needs to fight the standing wave for a long and arduous struggle.
The next step is:
After carefully observing the actual curve, the distance between the left and right sides of the room is not obvious at 57 Hz of the standing wave , because the table and the cabinet are placed from the left and right of my room, which does eliminate some effects. The influence of the standing wave before and after is quite powerful, but it is not very worried, because the speaker is placed in the middle during the test, so the relative length of the room is quite powerful. I will put a 34 in the recess of the window in the future. A 36 -inch 16:9 large TV, attached to the lower cabinet, and a fabric sofa on the other side of the listening room, should be able to eliminate some length effects.
It should be said that under the premise of the previous adjustment, the space spread will be better. Finally, according to the adjusted frequency response, several 2 cosine diffusion plates will be made, placed on the ceiling and the four walls. I believe that the frequency response of the whole house can be controlled well. .

Nagata's pocket resonator ( low frequency trap )
L=Q/4-A/2 , L= the height of the resonator, Q= wavelength Q=V/FV=340 , A= resonator side length
Yongtian's pocket-type resonator is a long rectangular box with a square plane. The bottom is not sealed and the four corners are long.
Four 30CM high feet can be made from six-point MDF boards and placed in the corners. In fact, the bottom of the speaker box is not covered with four legs.
F0=81.3HZ Q=340/81.3=4.2
Set the length of the box to 50*50cm, A=0.5
L=4.2/4-0.5/2=0.8, total height =0.8+0.3=1.1m
F0 = standing wave frequency

Added: Because my house was later put into a large cabinet, the size is 60x60x90 , placed under the window just under the center speaker, according to the calculation of the low frequency trap, just can eliminate the low frequency around 60-70 HZ , so later my The measurement curve of the house has changed. The 63 is sucking too much, I used the balance to make up 2 dB.........