i would probably advise against mentioning it in your secondaries and such because even though adcom can't discriminate on the basis of disability you don't want to give them any reason to doubt your ability to effectively communicate with people as required by technical standards. i could see how you could spin and talk about how it has shaped your experiences/view of the world, but you would have to be careful.
at interviews, just address it straight on. introduce yourself and say something along the lines of i have speech impediment, let me know if you need me to clarify anything i've said. you = 😎. that will indicate that a) you are aware of the situation/effects, b) you aren't scared ****-less, and c) are comfortable disclosing/address this aspect about yourself in a way that will open clear (and probably more effective) communication channels with patients.
