Tech Riddles – The Shepard

Planet Escher is inhabited by a human civilization, named the Shepard. Due to the extremely powerful light the star it orbits radiates, they've been forced to live in the darkness of the caves. Over the centuries, the Shepard have lost the sense of sight. Conversely, they've developed a formidable sense of hearing, and as a consequence, all of them are great musicians.

The Shepard are capable of communicating in different music dialects, being the most commonly used the "midi". When they're in danger, the Shepard emit a very disturbing tone that confuses their enemies. It's a very particular tone: it seems it never ends, it keeps ascending, or descending, endlessly. The Shepard take advantage of the state of confusion to escape or counterattack.

However, at least two Shepards are needed to make this sound. If two Shepards are in danger, and one of them sings:

1001000 00111101 01111111 1001000 00111110 01111111 1001000 01000000 01111111 1001000 01000001 01111111 1001000 01000011 01111111 1001000 01000101 01111111 1001000 01000110 01111111

What should the other Shepard sing?