I think that's called ambiance sound, or background noise.
Anyway, if that noise doesn't match the one in your grunt fx, then it'll be still bad (maybe a bit better than without any noise, though).
You have to find some grunt fx without almost no parasitizing noises (ie: ball & crowd), and remove the bg noise with a noise filtering function, usually available in most audio softwares.
== Mana Games ==
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