Deaf people already may learn to speak without that through speech therapy, although for most it’s not their preferred method of communication.

I don’t know how it’s changed in the modern day because the people I know who went through it as kids did it like 30 years ago, but it used to be common to hold a balloon against the throat while speaking to feel the different sounds you’re making.

Have you considered going outside and asking people your questions in order to only get answers from ‘mentally healthy’ people?

Honestly I’m thankful when someone puts the red flag above every comment themselves.