Audio format developed by the Nippon Telegraph and Telephone Corporation (NNT Labs); uses transform-domain weighted interleaved vector quantization to compress audio data; can be encoded in 80, 96, 112, 128, 160, and 192 kbps bitrates.
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.