See this is the awnser I was looking for THANK YOU +rep but how do i do this ?

This would require a data aquisition card, an instrumentational amplifier attached to a very sensitive inductor, and amplified so that the minute changes in electrical forces in the air generate a voltage of between 0 and 5V (a bit of knowledge of instrumentation would be required). A DAQ (data aquisition card) will have a built-in analog to digital converter, so if you just wire up this small amplified 'static sensor' to one of its inputs, it will store the value (from input 0-5V being output 0-4096) in a register. How you access this register depends on the DAQ setup, which can be an entire course on its own.

This is a pretty complex method to do a very simple task (generating a random number), and while it is possible it is pretty impractical. If you are new to programming, I would sugguest spending your time on other things.

this is retarded.
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You're right, it's major overkill. But it's the only answer in this thread remotely close to what the OP asked.

@OP: If you really want to use a microphone (and you use windows) click here. Then just use the x-first bytes from the data you got and it will be another way to get a semi-random-number.

My personal favorite for a random number is the Mersenne twister. (Lot's of free implementations available)