If you think about it, programs like Skype are just audio accelerators and amplifiers. Also, I would strongly recommend you DON'T try to make a sound loud enough to be heard 4000km away.
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From @corybralcortex
If you think about it, programs like Skype are just audio accelerators and amplifiers. Also, I would strongly recommend you DON'T try to make a sound loud enough to be heard 4000km away.