On April 1, 2014, the legendary Choir of King’s College Cambridge found a possible solution enabling older choir boys to continue to hit those angelic high Cs required for performing some traditional compositions. And on that particular day, the angelic assistance took the form of a big balloon of helium.
In this groundbreaking performance of Gregorio Allegri’s “Miserere” in the historic chapel, a male choral scholar is able to hit a C6 (a soprano C, to you and me) simply aided by a gulp of helium from his balloon.
From: ClassicFM.com