Ultra low bit-rate speech coding: An overview and recent results

In narrow-band speech coding, specifically in the low and ultra low bit-rate ranges, a series of efficient quantization of the LP parameters using fixed-length as well as variable-length segment quantization (VLSQ) have resulted in a progressive reduction in the bit-rate from the 2400 bits/sec baseline of the LPC-10 coder down to 300 bits/sec and less. The VLSQ framework forms a generic basis of a class of segment vocoders within which various...