What is the difference between anechoic chambers and soundproof rooms?

1. Soundproof room

Isolation Booth, also known as soundproof room, is used for clinical hearing examination, also known as audiometry room in the early stage. Pure tone hearing threshold test and suprathreshold function audiometry should be carried out in the soundproof room. In order to ensure the media bility of hearing test, it is required that the soundproof room must reach A certain degree of silence. In order to reduce the interference of external noise, the acoustic requirements of the soundproof room generally require indoor noise level < 26dB (A).
 
In order to meet the acoustic requirements, in the construction of the soundproof room, the outer wall should be smooth, in order to increase the reflection of the sound, reduce the sound into the sound insulation room; The inner wall and top surface, the use of porous sound absorbing materials, reduce the reflection of indoor sound. Rock wool and gypsum board are used for the inner layer, glass wool and flannelette are used for the outer layer, and carpet is laid on the ground to improve sound absorption performance and reduce reverberation time.
Anechoic chamber
Anechoic Chamber  in  the  field  of  acoustics  is  not  only  a  special laboratory for acoustic testing, but also an important part of the testing system. In fact, it is also one of the acoustic testing equipment, and its acoustic performance  index  directly affects the accuracy of testing. The main function of anechoic chamber is to provide a  free  field  space  or semi- free field space for acoustic testing. In the free acoustic field, there is only direct sound
without reflection sound. The sound absorption treatment of  anechoic  chamber  is the  key  to ensure t he good performance of free sound field after the completion of anechoic chamber. Most of them adopt the sound absorption wedge or plate type resonant sound absorption structure with strong sound absorption ability. Whether an anechoic chamber is a free sound field is mainly determined by its proximity to the ideal free sound field. Generally,  the law that the sound pressure is inversely proportional to the distance of the point sound source is used to test, and the allowable deviation is about ±0.5dB.
 
Anechoic chamber can be divided into full anechoic chamber and semi-anechoic chamber. The six faces of the room are fully laid with the sound absorption layer called the full anechoic room, generally referred to as anechoic room. Only in the six faces of the room in five or four face laid sound absorption layer called semi-anechoic room.