I love this part. I just read about it in Parke Puterbaugh's Phish: The Biography:

BLVR: In what ways do you work with Phish on improvisation? Like, improvising as a full band, rather than as four individual soloists.

TA: We had this series of exercises that we developed, called “Including Your Own Hey.” It sounds weird, but we did them a lot. They start off with a pulse. [Snaps in time] The first level is, I play a four-note phrase [sings “do-do-do-do”]; Page [McConnell] is on my right, and he imitates it on the piano; Fish [Jon Fishman] does his best to play it on the drums; then Mike [Gordon] does it on the bass. Now everyone goes around the room in a circle and everyone starts one.

BLVR: It’s a copycat listening exercise.

TA: Yeah, and then there were more levels. The next level is, I start a pattern and then Page harmonizes with it. We make a jigsaw-puzzle pattern. Then Mike finds his place in the pattern, and Fish finds his place in it. And we’re all listening to each other. Now, only when you hear that all the other musicians have stopped searching, once you hear they’ve locked in with what you’re playing, you say, “Hey!” So, since we’re still listening so intently to each other, we should all say “Hey” at the same time, but if we don’t—if someone says “Hey” when you’re still searching, they’ve basically just told you, “I’m not listening to you.” So we found, very quickly, that it meant you had to always be listening to three people other than yourself. And the music, we found, improved immensely by not navel-gazing. So now the idea is, I’m not paying any attention to myself at all. I’m just responding to what they’re playing.

Then there were other levels, where you’d leave a hole in a musical phrase, and the other person could only play in that hole. That was called “Including Your Own Hey Hole.” [Laughs] So the bass lands, then the cymbal, then the guitar. [Sings, “Ba-bo-da-bing, ba-bo-da-bing.”]

I hope the interviewer realizes just how lucky he was to have gotten this interview. I could listen to that man talk about music all damn day.