How to change audio in bedrock edition

So I'm making a texture pack, I also wanted to edit the sounds and change them up as I was doing this project with friends. My problem is I cant find anything on how to change the audio files as I'm almost 100% sure simply changing a file extension from .mp3 to .fsb isn't going to work. How do I accomplish this? Everything I see leads back to using Fmod studio, but that costs quite a lot of money, so what's the secret to changing bedrock sounds?