Take you to one of the quieter places in the world -- anechoic rooms

  1. What is an anechoic room?
A silencer chamber is a special sound environment that provides a free sound field for acoustic research and testing work. The inner wall of the silencer chamber is equipped with absorbing materials, and adopts sound insulation, vibration isolation and other treatment means, so that part of the indoor area to form a free sound field of "direct sound is large but the reflected sound is small". The six or five inner surfaces of the anechoic chamber are equipped with a wedge material with a sound absorption coefficient of more than 99%. The sound source is located in the center of the anechoic chamber, and the sound wave emitted by the sound is absorbed by the wedge. In the spherical area of a certain distance from the sound source, only direct sound waves are available.
The difference between semi-anechoic chamber and full anechoic chamber:
Anechoic room is divided into two types: full anechoic room and semi-anechoic room. The six faces of the room are all laid with sound absorbing materials, known as the full anechoic room, which requires small measurement error or the acoustic environment required by the directional characteristics of the measurement source, are generally designed as the full anechoic room; Only five or four of the six sides of the room are laid with absorbing materials, known as the semi-anechoic room. When the measured noise source is relatively heavy, difficult to place in the full silencer room and the measurement error is allowed to be large, the semi -silencer room is designed to complete its test work. The ground plane of the semi -anechoic chamber is generally polished cement, smooth floor and other materials that are almost completely reflective of the acoustic frequency sound waves.
Design requirements of anechoic chamber:
The design and construction requirements of anechoic chamber are mainly the type selection of anechoic chamber, the size and shape design of anechoic chamber, the sound absorption structure design of anechoic chamber, the sound insulation design and construction of anechoic chamber, the vibration isolation design and construction  of  anechoic chamber,  the  Background noise measurement of anechoic chamber  and  the  identification  of  the  free  sound field of anechoic chamber.
The volume of the anechoic chamber is mainly determined by the size of the measured sound source and the test distance, and is also related to the size of the allowable measurement error, the cutoff frequency of the test, and the wall sound absorption coefficient.