Another user mentioned the Privacy Pass solution: https://news.ycombinator.com/item?id=23902870
While Privacy Pass is not perfect, we are working towards getting better. I'm not in the product flow for accessibility, but if you have ideas outside of audio that you believe would be able to distinguish between yourself and a robot, I'd be happy to discuss via email to ensure that we can get a solution for you and anyone who can reasonably interact with a computer.
eta: you can email me directly at work via: josiah@intuitionmachines.com