I've always been shy and quiet but I do talk at work sometimes but they tend to say "what" to me. To me, I sound like I talk at a normal level. Im not sure if they just can't understand me or if I'm too quiet. I start to feel a little depressed because of this.

I've been struggling with this my whole life but will it get better as I get older?

What about when you talk to people away from work?

There are groups like "toastmasters" that help teach public speaking, they are great.

Also just practice all the time talking in what I call a "outdoor voice"

what about when you talk to people away from work?
I talk at a normal level. Its just work where I'm having a hard time

Maybe it's a noisy work place or the people are hard of hearing, so adjust by talking a bit louder.

On an older post about a favorite teacher, you finally told us that you have hearing loss, yet you don't mention it in this post at all! It's very understandable that you aren't sure how soft or loud your voice is, and you don't want to sound like you are shouting, so you tend to speak softly. So if someone says 'what,' just say it again a little more loudly.

I know people who have no hearing loss who mumble and I have to say 'what' a lot, and I don't want to, so I stop, and then I miss most of what they are saying, and then the whole conversation gets all confused. I suppose it's funny in retrospect.

Maybe its a noisy work place or the people are hard of hearing, so adjust by talking a bit louder.
I try