sometimes i hear a random cry when i'm playing (this is fire red/ leaf green)
it might just be that i dont notice it at other times but i swear it happened twice when i was using a repel (i was searching for entei) does anyone else get this or know what it is?

I think that's supposed to happen. I've heard something like this before...don't remember if fully though. I think the idea was to make the game more realistic.

Every so often you'll hear cries from Pokemon in the area, and iirc, your party Pokemon as well.

I think it just might be the sound of two things clashing together to make it.

No; it's the pokemon.
I've nearly destroyed my emerald cartridge because the Golbat cries were annoying the hell out of me. *Sigh* The pure annoyance victory road makes...

hey guys,epesely blazikendude,on the internet somewhere,i read that,no it was my friend that said "If you have the volume up,it just puts more pressure on the gameboy and uses the juice in the batterys and uses the batterys up more"

And your point is? The sound is to add enjoyment. Without the sound, your mother might think you're playing pac-man. And for the question, they basicly just tell you that a certain species of pokemon lives in your current area, nothing special.

oh.so if i was at say,oh i dont know,route 101,i would know if there was spoink there if i had him?(saying spoink just hypeteticly)

A better example:
If you're in Rusturf tunel you might hear a Wismur. But if you are in te Magma hideout you will not hear a Wismur even if you're stupid and have one in your party.