From a barrel longer than 4.5" you will hear the supersonic "crack" as the bullet breaks the sound barrier. Also if shooting semi auto you will hear action noise and ejection port pop.
depending on weather, surroundings etc, sometimes i hear a faint little pop with my 16" bolt rifle. other than that, it's pretty quiet. CLICK.......................TING! as far as HV, you still hear the crack. it is still annoying to the hippy neighbors and they will complain about the noise. ask me how i know.
on my ruger MKII, the CCI SV and the misc HV ammo i have sound the same as fungun mentioned. so i don't waste SV in a pistol.