September 18, 2020
[Updated to include new software on October 26, 2020]

Note: A shorter version of this article was also published as guest blog post for SmartMusic.com

Introduction

In 1957, while prohibited from traveling outside the US because of his political activism, Paul Robeson performed on a choral festival in Wales run by a mineworkers union. Yet he did not defy the McCarthyite attack on his freedom by traveling to the UK in person: Instead, Robeson participated from a New York City recording studio, sending his powerful, bass baritone presence over newly laid transatlantic telephone lines.

That concert’s audio quality…