I want you to design a sound-proof phone case which would block sound from entering the phone case, but NOT block signals.
So, it needs to be able to take calls, but to block out sound.
It is for anti-spying to prevent a room bug from recording all background noise near to the phone.
Studying the design of this product may help you:
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I only need the basics of how it works.. such as
1. What materials are used to block sound..? Led..? Aluminium..? Etc
2. What kind/size of case
3. How to broadcast the phone call from the inner box to the outer box so you know when you have received a call