The anechoic chamber is called the quietest place in the world. There are many negative decibel anechoic chambers abroad, such as Microsoft's full anechoic chamber in Redmond, Washington, D.C., and Orfield's anechoic chamber. In our country, there is also a negative decibel anechoic chamber: the anechoic chamber of Guizhou Electrical and Mechanical Quality Inspection Institute. The anechoic chamber was designed and constructed by Shanghai Fund Acoustics Engineering Co., Ltd. And it is tested by the Building Physics Laboratory of Tsinghua University and the Chinese Academy of Metrology respectively. The background noise is -1.0dB (A)!

The normal voice of conversation between people is about 40 - 50 decibels. At night, the voice in bedrooms is about 30 decibels. Can you imagine how quiet negative 1dB (A) is? In a room where 99.99% of the sound waves above the cut-off frequency are absorbed, you can even listen to your heartbeat.

The engineer of Fund Acoustics told us:"Once you enter the anechoic room of Guizhou Electrical and Mechanical Quality Inspection Institute, you will feel that the whole world is suddenly quiet, and you can clearly hear the friction of clothes when you walk. The longer you stay here, the quieter you will feel. And you will hear more. In addition to your own heartbeat, sometimes you can even hear the sound of your lungs and the grunt of your stomach. In such a negative decibel environment, we ourselves have become the biggest source of sound!"

The anechoic chamber of Guizhou Electrical and Mechanical Quality Inspection Institute covers an area of 280 square meters. The interior of the anechoic chamber is crisscrossed with metal sound absorption wedges. Under the feet is a steel wire mesh built in the air. The whole space has a full sense of shape, as if in the world of science fiction.

Fund acoustics acoustics expert warned in particular: "Because it's so quiet here, you may need to adapt yourself to the sound you make when you walk. Here, all the sensory clues that can help you balance and regulate yourself disappear. Experiments have been done abroad, and the longest time someone can tolerate in such an acoustic environment is only 45 minutes.