GSM 06.10 Lossy Speech Compression. A lossy format for compressing speech which is used in the Global Standard for Mobile telecommunications (GSM). It’s good for its purpose, shrinking audio data size, but it will introduce lots of noise when a given audio signal is encoded and decoded multiple times. This format is used by some voice mail applications. It is rather CPU intensive.
A file with the CDDA file extension is a CD Digital Audio file that stores audio in the AIFF format. CDDA files are normally seen only when audio files have been ripped from an audio CD that uses the CD Digital Audio specification. This is most often done through the Apple iTunes program with the Audio CD burn option.