Edgard Varèse conducting a workshop of Jazz musicians in the year 1957. Here is the original announcement of the mp3 release of these tapes. Edgard Varèse conducts a workshop with jazzmen Art Farmer (trumpet), Hal McKusik (clarinet, alto sax), Teo Macero (tenor sax), Eddie Bert (trombone), Frank Rehak (trombone), Don Butterfield (tuba), Hall Overton (piano), Charlie Mingus (bass), Ed Shaughnessy (drums), probably John La Porta...