Item – Theses Canada

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OCLC number
63124474
Author
Radwan, Ayman,1976-
Title
Non intrusive speech quality assessment in VoIP.
Degree
M.A. Sc. -- Carleton University, 2003
Publisher
Ottawa : Library and Archives Canada = Bibliothèque et Archives Canada, [2005]
Description
2 microfiches.
Notes
Includes bibliographical references.
Abstract
VoIP is a promising technology that is expected to replace traditional telephone networks. Although VoIP is efficient, its speech quality is still less than what telephone users are accustomed to, due to packet loss, excessive delay, and clipping. Network administrators need to maintain certain level of quality by monitoring speech quality of live calls for actions to be taken. Subjective methods are unsuitable for live calls assessment. Objective intrusive methods mandate a reference signal, therefore cannot monitor live calls. The only suitable method is the E-model that estimates the speech quality based on statistics collected from the network. In this thesis, speech quality is estimated based only on the received degraded speech signals. Work is focused on packet loss and clipping in time which are significant and unique to VoIP. In case of packet loss, it is assumed that a lost packet is replaced by either silence or the previous packet. In each case, a method is provided to model the process then obtain an estimate of voice quality. In case of clipping, speech quality score is estimated based on the estimate of the threshold that caused the clipping. Simulation results show that speech quality can be estimated with an error less than 0.5 in MOS score in the majority of speech files examined.
ISBN
0612973956
9780612973954