TheGray Audograph was adictation machine format introduced in 1945. It recorded sound by pressing grooves into softvinyl discs.[1][2]
The Audograph recorded on thin vinyl discs of 15cm diameter, recording from the inside to the outside, the opposite of conventionalgramophone records. Unlike conventional records, the disc was driven by a surface-mounted wheel. This meant that its recording and playback speed decreased toward the edge of the disc (like theCompact Disc and other digital formats), to keep a more constant linear velocity and to improve playing time,[3] which was ten minutes.[4]
In 1950, Gray began to make a variant of the Audograph forAT&T, known as thePeatrophone.[5]
