Why does my iphone 4 lock sound have such a delay?

When I lock my phone it takes about 4/5seconds for the lock noise to go off, why?

Umm how about turn it off like everyone else?

Sometimes after working for a while the phone has to catch up so the sound takes a while to process, it's not broken just a little bit behind

I'm not sure of the reason, but try resetting your phone (settings) as it speeds it up somehow

Have you recently dropped or damaged it? , mine did the same, i dropped it and the sound was a little delayed but it should stop after a while and go back to normal, or it could be a technical fault.