No, I never use speech to text on the phone. It would be yet another tether to the phone, which I don't carry constantly like many others.

But it would help in many situations. I use closed captioning on the TV, which is much the same but in that case, I am the captive of the video and feel no remorse at ignoring the speaker and looking at the captions.

I've often thought that it would be useful to "translate" what I hear for others. It would give them a much better appreciation of the disability.