Fully soundproof room

Silencing room category

1.Type of anechoic chamber ：Fully anechoic chamber、semi-anechoic chamber、Simple anechoic chamber
Type of sound-absorbing material: glass wool wedge Metal Spike Flat anechoic chamber
Soundproofing board type: mixed brick civil structure，Metal sound insulation and absorption board
Vibration isolator type: Spring isolator，Rubber isolator
Type of ground grid for fully anechoic chamber: Steel wire soft grounding network，Reinforced hard grounding network
2.Function of anechoic chamber
Mainly used for automobiles、Electromechanical、home appliance、Precision testing of communication products and other standard experiments.
3.消声室性能：
for example：The background noise is less than5dB，cutoff frequency80hz.
4.Characteristics of anechoic chamber：
Standard Acoustic Free Field Space，Used for precision acoustic testing,Provide a third-party testing and calibration report.
anechoic chamber（semi-anechoic chamber）It is an experimental environment for conducting various noise tests and acoustic research.While inheriting years of research achievements in the field of acoustics，Combining one's own practical experience in engineering，Designed and constructed multiple distinctive anechoic chambers in China.
design
After fully understanding the customer's needs，Design the anechoic chamber according to standards.The acoustic indicators in the design include background noise、cutoff frequency、Available space、Vibration reduction, etc.On the premise of meeting acoustic indicators，Simultaneously consider the convenience of use in the design、Sharp splitting door、specimen（product）Installation and transportation、ventilation condition、Instrument wiring、Monitoring conditions、Indoor environment, etc.Every anechoic chamber designed is a masterpiece of interior decoration.
Free field space
The main function of the anechoic chamber is to provide a free field space or semi free field space for acoustic testing.Free field refers to the propagation of sound waves in infinite space，There are no reflectors or reflective surfaces present.
The free field space in nature is the suspension of sound sources in the air，Stay away from reflectors，Sound waves can freely move towards360°Full angle propagation.A semi free field space refers to a free space with a total reflection surface，Sound waves can only be180°Free propagation in hemisphere orientation.Common semi free field spaces such as large open-air parking lots with cement floors、Outdoor basketball court、apron…wait.
There is a specific physical definition for the propagation of waves in free or semi free field space.
（1） The sound pressure of a point source decays with distance，This is the inverse square law of sound energy
（2）The sound pressure level is equal to the sound intensity level at room temperature and pressure.This is the theoretical basis for measuring sound power in an anechoic chamber.According to the national standardGB6882－86＜＜acoustics Determination of sound power level of noise sources - Precision method for anechoic and semi anechoic chambers＞＞，Within the testing frequency range，The sound pressure level of background noise is at least lower than that of the measured sound source6dB，low12dB.
cutoff frequency
An anechoic chamber is designed to simulate a free field or semi free field space indoors，So the required wall sound absorption coefficient is99%above.The reflection coefficient of the semi free field ground is95%above.Design a method that can achieve full frequency band（20 Hz – 20000 Hz）of10 0%absorber，It's impossible.Because common materials are easily absorbed by high-frequency sound waves，And low-frequency absorption depends on the thickness of the material（The length of the spike）concerning.The cut-off frequency refers to the frequency above this frequency，The sound absorption system on the wall can ensure99%The sound absorption coefficient.In actual engineering（half）Free field space refers to sound waves above the cutoff frequency，The soundproof room is（half）Free field space，The lower the cut-off frequency，The longer the requirement for the length of the spike, the greater the.generally speaking，The length of the spike is suitable for1/4Wavelength theory.
Identification method for anechoic chamber
In practical engineering，Free space of sound field is the key basis for identifying the quality of anechoic chamber.National StandardISO 4744In accordance with national standardsGB 6882－86Provided a method for identifying the free space of an anechoic chamber.
in addition，Background noise is another important indicator of an anechoic chamber.The background noise obtained in the measurement is the background noise of the instrument plus the background noise of the anechoic chamber.