What is the difference between the audio formats?
There are many different formats in which audio information can be presented, from cassette tapes and CDs to electronic files. This is an area in which technology is always developing, and new formats that are introduced aim to improve the consumer experience, by adding additional functionality or flexibility.
One key difference between formats is the way in which the audio is actually stored - as an analogue or a digital signal. More modern formats use digital encoding, whilst the cassette tape uses analogue encoding.
What is the difference between analogue and digital audio?
Analogue recording is when the properties of the sound wave are physically recorded onto the recording medium (e.g. grooves in a record or magnetisation on tape). Therefore the recording is "analogous" of the physical properties of the sound. When played back, these physical modifications cause the same sound to be reproduced.
Digital recording takes samples of the sound wave, and records it as numbers (digits), so the data is stored as a string of numbers rather than directly reflecting the properties of the sound. When it is played back, these numbers are converted back to an analogue wave and the sound is reproduced.
The main benefit of digital recording is that it does not wear out over time. With analogue, as the recording is played over and over, the physical record is eroded and can be destroyed. With digital, the same numbers produce the same sound time after time.
Controversy remains over the relative merits of analogue and digital technology, although digital formats are widely thought to be better quality, have greater capacity and be easier to navigate than their analogue counterparts.
Related research reports
RNIB has carried out research into the how the transition from analogue to digital audio may affect blind and partially sighted people. The study involved looked into availability of media, transcriber views, and user views. A summary report is also available. Reports published Spring 2008.