Drones A4 = 440 Hz Twelve chromatic drones. C Play or download MP3 C# Play or download MP3 D Play or download MP3 Eb Play or download MP3 E Play or download MP3 F Play or download MP3 F# Play or download MP3 G Play or download MP3 Ab Play or download MP3 A Play or download MP3 Bb Play or download MP3 B Play or download MP3