smooth sound

Welcome to TN !!!

That can be many many things... Could you give us more details on this kind of noise ? Is this happening while you have a/c on ? Have you had your tyres balanced recently ? A bit difficult to say if we don't have more details...

I like my car to sound smooth, especially the tranny.

that's sound coming when i switch ON a/c . i had tyer balancing . and NO change in that .

That's probably just the normal sound of your compressor. Have you had recent works done to your a/c system ? If no I would not really worry, this is normal...

I think the real question here is, is it impairing your driving ability?

What I mean is does this sound in any way prevent the engine from operating normally and you from driving normally.

This should help to diagnose what the problem is, if there even is a problem.