Is there any difference between the production of an anechoic chamber and an anechoic chamber?

The standard anechoic chamber has four sound-absorbing surfaces, the listening room has six sound-absorbing surfaces, the room is a free field, and a layer of steel wire mesh structure with a diameter of 4mm is made as a working plane at a low position in the middle of the anechoic chamber.

An anechoic chamber is the creation of a "free sound field" in an enclosed space. The so-called "free sound field" means that in a closed space, sound waves can be transmitted freely, without the reflection of obstacles, and without the interference of environmental noise, such a space is called "free field". The establishment of a completely free sound field in a room is only approximate, because all materials and structures cannot theoretically have an absolute 100 sound absorption condition, and in the design of anechoic chambers, it is necessary to meet the conditions of the free sound field test radius at what frequency and in what space and how much it deviates from the theory.

If the six sides of the anechoic chamber are fully covered with strong sound-absorbing layers, it is called a full anechoic chamber, which is generally called an anechoic chamber. And only four or five of the six surfaces are covered with strong sound-absorbing layers called semi-anechoic chambers.

There is no difference between the anechoic chamber and the anechoic chamber (reference: Eiffel Acoustics) in the test of the listening properties of the sound source, the production of the anechoic chamber can be four sound-absorbing surfaces, the full anechoic chamber has six sound-absorbing surfaces, the room is a free field, in the middle of the anechoic chamber low position to make a layer of steel wire mesh structure with a diameter of 4mm as the working plane, the size and volume of the anechoic chamber depends on the size of the sound source and the distance between the sound source and the listening microphone.

There is no difference between the anechoic chamber and the anechoic chamber (design: static ring environmental protection) in the test of the listening properties of the sound source, but the requirements of the anechoic chamber are more stringent, the standard anechoic chamber is four sound-absorbing surfaces, the anechoic chamber has six sides for the sound-absorbing surface, the room is a free field, in the middle of the anechoic chamber low position to make a layer of steel wire mesh structure with a diameter of 4mm as the working plane, the size and volume of the anechoic chamber depends on the size of the sound source and the distance between the sound source and the listening microphone, the length and width of the anechoic chamber should be greater than the measurement range of 1 2. The volume of the listening room should be greater than 200 times the volume of the measured sound source.

Before the top of the anechoic chamber is suspended, the structural strength and installation reliability of the top split pylons should be checked and accepted, and then the top split installation should be carried out. When installing the ground split, when the pitch skeleton has considered the cavity size support structure, the tip splitting body can be directly placed on the ground.

The anechoic chamber first needs to clarify the goals to be achieved, and the three most important parameters are the free field radius, cut-off frequency, and noise floor. Once you've identified your goals, you need to consider the following questions during the redesign process.

a. Whether there is a noise source around and how loud the noise is; whether there is a source of vibration around the anechoic chamber; Whether the surrounding noise sources and vibration sources are in working condition during the use of the anechoic chamber; Whether there are frequent people walking around the anechoic chamber during use, especially the movement of high heels; All of this can have a significant impact on anechoic chambers with low noise floor requirements. Therefore, a full investigation and understanding of the target noise floor and the environment that needs to be achieved in the anechoic chamber is the prerequisite for a anechoic chamber. Especially in anechoic chambers where the noise floor is less than 20dB, any omission can cause the project to fail.

b. The door of the anechoic chamber is one of the key points of sound insulation treatment, and usually the door is also a weak environment for the sound insulation of the anechoic chamber. The design of the anechoic chamber door should first consider the noise influence of the surrounding environment and the noise floor required by the anechoic chamber.

c. Usually the anechoic chamber will also have the demand for ventilation and air conditioning and the access of various pipelines required for production. For ventilation and air conditioning, it is recommended not to set up ventilation equipment and air conditioning equipment in the anechoic chamber, even if it is set up outside the anechoic chamber, do not have a direct rigid connection between the equipment and the anechoic chamber, and the inlet and outlet air are introduced or led out by flexible air ducts and mufflers, and the influence of wind speed on the anechoic chamber should be fully considered. For anechoic chambers with low noise floor requirements, it is recommended not to use ventilation and air conditioning systems when using them.

The access of various pipelines should be well protected and sealed.

Normally, the above issues must be considered for a good anechoic chamber design.

The relative humidity of the anechoic chamber is not more than 70%, and the noise reduction and silencing design of the ventilation and air-conditioning system should be determined according to the allowable noise level in the anechoic chamber, the noise value of the equipment, the vibration magnitude, the frequency characteristics and the noise of the transmission system.

The main function of the anechoic chamber (installation: Static Ring Environmental Protection) is to provide a free-field space or semi-free-field space for acoustic testing. Free field refers to the absence of any reflectors and reflecting surfaces when sound waves propagate in an infinite space.

The free space of the sound field is the key basis for identifying the quality of the anechoic chamber, and the noise floor is another important indicator of the anechoic chamber. The noise floor obtained in the measurement is the noise floor of the instrument plus the noise floor of the anechoic chamber.

Reference: Eiffel Acoustics) Anechoic chamber and hemi-anechoic holding chamber of several points of the positive skin annihilation:

1. Design differences: all six sides of the full anechoic chamber are muffled, and only five sides of the semi-anechoic chamber are muffled.

2. Difference in acoustic effect: the acoustic effect of the full anechoic chamber is higher than that of the semi-anechoic chamber, and the test precision is higher.

3. Differentiation of the district: the anechoic surface of the full anechoic chamber is more than that of the semi-anechoic chamber, and the cost is correspondingly higher.

This is not good to do without professional technology, and it is difficult to achieve the desired effect when it is made, so you can find a professional to do itAnechoic chamberof the company to do it. Do it yourself plus the cost of manual technology and materials is not low, it is more worry-free to pack it out, and the technology is better.

Hemi-anechoic chamber designThe floor is not muffled, only the walls and ceilings are muffled. Specifically, it is mainly vibration isolation and sound absorption treatment, forming a free sound field in the anechoic chamber, and achieving the ideal effect by installing sound absorption sharp splits.

Whether the performance of the anechoic chamber meets the requirements of use is generally tested by the method of verifying the free field, that is, the sound pressure generated by the point sound source should be inversely proportional to the distance to the sound source, and the deviation between the measured sound field and the ideal free field is the main tremor index used to measure the performance of the anechoic chamber. In general acoustic testing, this deviation is required to be no more than 1dB; For microphone calibration, it is required that this deviation is not greater than in the vicinity of the calibration distance.

In addition to meeting the requirements of the free field, the anechoic chamber also requires a low background matching noise. Therefore, between the anechoic chamber and the foundation, certain vibration isolation measures need to be taken.

For people who enter the anechoic chamber for the first time, they are really unaccustomed to it, and the auditory sensation of the outside world is completely different, there is no echo when high-fived talking, and the sound of clothes and pants rubbing when walking is unprecedentedly clear, and it seems that you can hear the sound of your own blood flowing quietly here without saying or moving. In this extremely quiet environment, anyone who comes into contact with an anechoic chamber for the first time immediately feels lonely and slightly afraid.