the ear drums are tuned in a precise rfrequency range... animals have a better hearing and they would still no hear it
human range:20-20 000 Hz
http://www.norsonic.com/web_pages/human_hearing.html
on top of the remarqs they have, you have to add the capacity of the humain brain to solve teh so called tea party problem( simply put you are at a party and everyone is talking...assuming you are sober, you WILL be able to identify the voice of someone who is very close to you: mom/ dad brother best friends... while filtrering everyhting else That is not possible for pc's right now, imagine the applications in cell phones ...)


you can' hear the sound of the big bang cuz their range are in the are 0.01 to 0.001 cycles/second... (do a search on google...)

also, you wouldn't hear them because to hear them you must be wittin range of hearing
assuming the big bang occured it would have pushed matter and sounds in all direction (assuming they travel at the same speed which is not possible...) take the time for suns to aggregate then planets then life or whatever ... then there is no way you could hear something that is long gone... you could consider the case where the sound might be reflected and the reflexion acting as a new source but ...
so go to http://www.naic.edu/genpubx.htm and tune in !!!

i'll get ime to write a tute about signals and systems...