Why is the audio quality of the recording when camera is inside waterproof housing not as good as when camera is not inside waterproof housing? (YI 4K+ Action Camera)

We use high-quality material to build our waterproof housing. It is very strong and reliable. On the other side, it blocks sound from transmitting from the sound source to the microphone of the camera. The housing also gives additional pressure to the microphone. All of them may impact audio quality when the camera is inside the housing. We recommend customers not using waterproof housing when audio quality is critical. And we also recommend customer install the housing in the following ways to reduce the impact of the housing: 1) power up the camera and turn on 'In Housing' mode. 2) power off the camera, 3) put the camera inside the housing, 3) close the lid of the housing slowly. 4) power up the camera and start to use it.