Michael A. Ramalho

Emerging ITU-T standard G.711.0 — lossless compression of G.711 pulse code modulation

The ITU-T Recommendation G.711 is the benchmark standard for narrowband telephony. It has been successful for many decades because of its proven voice quality, ubiquity and utility. A new ITU-T recommendation, denoted G.711.0, has been recently established defining a lossless compression for G.711 packet payloads typically found in IP networks. This paper presents a brief overview of technologies employed within the G.711.0 standard and summarizes the compression and complexity results. It is shown that G.711.0 provides greater than 50% average compression in typical service provider environments while keeping low computational complexity for the encoder/decoder pair (1.0 WMOPS average, <;1.7 WMOPS worst case) and low memory footprint (about 5k octets RAM, 5.7k octets ROM, and 3.6k program memory measured in number of basic operators).

A new speech enhancement technique with application to speaker identification

Speaker identification (SI) and speech recognition systems display a strong sensitivity to ambient noise conditions. It is known that the performance of these systems is maximized when trained under conditions that approximate the testing environment. However these systems generally do not perform well when there is no noise or when the level or characteristics of the noise changes. A new speech enhancement technique is presented that, when used with a standard cepstrum-based SI system, significantly reduces the sensitivity of the SI system to mismatches in the noise environment between training and testing.<<ETX>>