The design principle of a semi anechoic chamber is mainly to provide a semi free sound field testing environment, which helps to accurately measure the noise characteristics of the equipment. The following are some key principles and technical details of semi anechoic chamber design.
 
1. Basic concept of semi anechoic chamber
 
A semi anechoic chamber is a special type of acoustic laboratory designed to simulate the acoustic environment of a semi free space. In this environment, except for the ground, the other five surfaces are covered with strong sound-absorbing layers, and the ground serves as a reflective surface, so that when the sound source radiation surface and the ground are in a plane, the sound propagation situation is the same as in a conventional soundproof room.
 
2. Selection and arrangement of sound-absorbing materials
 
The sound-absorbing material of a semi anechoic chamber is usually a conical or wedge-shaped sound-absorbing body made of porous and multi fiber materials, which can efficiently absorb sound waves. The length of the sharp edge is related to low-frequency absorption, and the cutoff frequency refers to the sound absorption system of the wall that can ensure a 99% sound absorption coefficient above this frequency.
 
3. Structural design
 
The structural design of a semi anechoic chamber includes two aspects: sound insulation and vibration isolation. Sound insulation design usually adopts a "room in room" structure to improve the sound insulation effect. The vibration isolation design is carried out through a floating ground with an elastic cushion layer to isolate solid sound caused by impact.
 
4. Door design
 
The door of a semi anechoic chamber needs to have good sound insulation performance, usually consisting of soundproof doors and sound-absorbing split doors. This design ensures that the indoor free field is not disturbed by external factors.
 
5. Aerodynamic performance
 
The design of a semi anechoic chamber also needs to consider aerodynamic performance to ensure that indoor air flow does not affect test results. This usually involves the installation of exhaust systems and the use of mufflers.
 
6. Monitoring and Lighting System
 
The construction of a semi anechoic chamber also needs to consider the installation of monitoring and lighting systems, which are essential for testing and may also have certain impacts.
 
7. Construction and acceptance
 
The construction of a semi anechoic chamber needs to be carried out by a professional acoustic design company to ensure compliance with acoustic research standards. After the construction is completed, a series of tests and acceptance are required to ensure that its acoustic performance indicators meet the requirements.
 
In summary, the design principle of a semi anechoic chamber is a complex system engineering that involves multiple aspects such as the selection and arrangement of sound-absorbing materials, structural design, door design, aerodynamic performance, monitoring and lighting systems. These design principles work together to provide an ideal semi free sound field environment for acoustic testing.