that is only useful for severe cases of disabled people, especially those who cannot even move their hands. for most people who can't speak, there are already other ways of communication: [Augmentative and alternative communication - Wikipedia](https://en.wikipedia.org/wiki/Augmentative_and_alternative_communication). and for those who can speak but have speech impediment, that is, most of us, it's better to rely on A, A, T. A: Accommodation A: Acceptance T: Therapy Anything outside of A, A, T is either experimental and risky or scam.