GSM-AMR (AMR-NB) Vocoder

GSM-AMR is a standard adapted by the 3rd Generation Partnership Project (3GPP). It is an Adaptive Multi Rate-Narrow Band (AMR-NB) speech codec. This vocoder is used mainly in 3rd generation mobile telephony devices to compress toll-quality speech at 8000 samples/second. GAO’s GSM-AMR codec has eight basic bit rates, 12.2, 10.2, 7.95, 7.40, 6.70, 5.90, 5.15 and 4.75 Kbit/s. The algorithm utilizes the Algebraic Code Excited Linear Prediction (ACELP) technique for all bit rates.