Of a mountain, because i can hear the expanse of space around me. i can listen to birds, i can listen to the waterfall i hear right now in the background. >> it's going to get really narrow. he was telling me just about how he's been guided up mountains, like, using a voice system and i'm like, well, i have a voice. >> reporter: and he now counts on that voice. >> and then to the right a little bit. >> we both serve a purpose on the trail and, you know, a huge responsibility, you know, to each other. >> reporter: sending us this on their hike today. >> hi, david! >> hi, david! >> today we are ...