Why can't people hear me when I talk.

When  I was younger I was very shy, not only that I was quiet too.
I don't just mean, didn't talk much (I mean that too).
Looking back it felt like no one heard me when I spoke.
Adults were constantly telling me to speak up.
As I grew up the volume in my voice didn't get better.
People stopped saying speak up and started saying

'Pardon'  and
'What did you say?'

When you hear it once or twice its fine, but when you hear it for the 100th time it starts to chip at your confidence.
Then I started thinking what's the point of talking if no one is going to hear me.
I went through what I went though and now that I've gain my confidence and am constantly adding to it.
Now I don't really get people saying speak up at all.
I don't get people saying pardon or what did you say? (Maybe once in a while).
I just get the move forward with a hand to their ear.
Which is so, so anoying it makes me want to scream.
Instead I just do it inside and don't let it get to me.
The same way I don't let the little things that lead to my depresion lead to it again.