The main difference between a fully anechoic chamber and a semi-anechoic chamber is the different requirements for the acoustic environment.

Full anechoic chamber:
1. The walls, ceiling and floor are all made of special sound-absorbing materials, which can effectively eliminate indoor sound reflections.
2. The indoor acoustic environment is controllable and can be used for acoustic testing and experiments.
3. Mainly used for R&D, production and testing of acoustic products with high acoustic requirements, such as speakers, headphones, etc.

Semi-anechoic chamber:
1. Only some walls, ceilings or floors are made of sound-absorbing materials, and the control of sound reflections is relatively low. Basically, most semi-anechoic rooms do not have special sound-absorbing treatment on the floor, so only 5 sides have good sound-absorbing effects.
2. Compared with a fully anechoic chamber, the cost and construction difficulty of a semi-anechoic chamber are lower.
3. It is suitable for projects that have certain requirements on the acoustic environment, such as recording studios, studios, etc., which are not as demanding as acoustic testing.

The main difference between a fully anechoic chamber and a semi-anechoic chamber is that the requirements for the acoustic environment are different. The fully anechoic chamber has stricter control over sound reflection and is suitable for high-precision acoustic testing, while the semi-anechoic chamber is suitable for occasions that have certain requirements for the acoustic environment.