Audio letter
Introduction The Compact Cassette, typical medium for audio lettersAn '''audio letter''' is an audio recording sent by postal mail to a recipient. The practice was more common when charges for long-distance telephone services were higher and before the widespread use of the Internet.Discovered audio recordings offer a unique perspective into that time period and have often been used to present historical context in modern-day radio and television programs.
Media Media used in recording audio letters include:* Wax cylinder* Reel to reel* Cassette tape* MiniDisc
References *  MPR Perspective on Vietnam wartime audio letters
External links *  The Audio Kitchen