I know what you mean. That’s called hypnagogic sounds (am i right? 
) Well you probably read somewhere on this site about HI , thats about the same thing, except this is sounds instead of flashing colors, shapes and stuff.
Well I had quite some experience with that… since I was like 10 I tried to ‘capture’ the exact moment when I fall asleep, you know like line between ‘awake’ and ‘asleep’ and experienced the stuff you’re talking about quite a lot of times. At first I just heard, like, just a sound of someones voice, but could not understand what they were saying. But now i can hear the strange things, exactly like the ones you’re talking about… and usually not in my voice but in someone elses, like someone i heard speaking a lot through the day. Sometimes I try to remember some of this things I hear, but they are just so strange that i forget them in the morning (I do remember some of them but they are in croatian and practically unable to translate).
I’m gonna try to catch some tonight 
P.S. you’re not crazy … i think… 
EDIT: found a topic !