How do you sign if you’re holding an ice ax? Do guides refuse to work with you if you can’t hear? What happens if you can’t see each other signing at night?

Those are just some of the issues that American adventurers Scott Lehmann and Shayna Unger have addressed on their YouTube channel, which documents their experiences as a Deaf couple working their way to the peaks of the world’s tallest mountains.

On May 22, Unger and Lehmann became only the third and fourth Deaf people to summit Mount Everest. Unger is the first Deaf woman ever.

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