 MPEG-1 Audio Layer III (the first version of MP3) is a lossy audio format designed to provide acceptable quality at about 64 kbit/s for monaural audio over single-channel (BRI) ISDN links, and 128 kbit/s for stereo sound.MPEG-1 Audio Layer III was derived from the "Adaptive Spectral Perceptual Entropy Coding" (ASPEC) codec developed by Fraunhofer as part of the EUREKA 147 pan-European inter-governmental research and development initiative for the development of digital audio broadcasting.ASPEC was adapted to fit in with the Layer II model (frame size, filter bank, FFT, etc.