G.723.1 is a dual rate speech coder for compressing the speech or other audio signal component of multimedia services at a very low bit rate. This coder has two-bit rates associated with 5.3 and 6.3 kbit/s. The higher rate has greater quality. The lower rate gives good quality. It is possible to switch between the two rate at any frame boundary. The principal application considered was very low bit rate visual telephony as part of the overall H.324 family of standard.

To enhance the error robustness of G.723.1, we propose a new error protection scheme by applying BCH(63, 51) to significant bits in a frame and performing an adaptive error concealment procedure. Objective and subjective evaluation tests all show that with a reasonable increase of the bit rate the quality of the reproduction of G.723.1 with the error protection scheme and adaptive error concealment procedure is significantly better than the original G.723.1 at a wide range of channel error rate.