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doi: 10.1177/003754979807000503pmid: N/A
Speech coding is a well researched area, and researchers are making new proposals for im provements to current algorithms. The family of code-excitated linear prediction coders rep resents a recent breakthrough, which almost caters to the present need for low bit rates. In mobile communications, low bit-rate speech coders play a crucial role in spectrally efficient transmission. Theoretically, a rate of a few hundred bits per second is enough to code speech efficiently. Many coders have been de veloped using computationally intensive tech niques that can achieve rates of 4 to 6 kilobits per second. Theoretically, there is room for improvement. The trend is to use analytical models of speech production and perception. This paper briefly reviews existing speech cod ers, identifies future trends in this research area and describes results obtained from simu lating vowels and consonant waveforms and from a multi-pulse excitation/linear predictive speech coders algorithm.
doi: 10.1177/003754979807000504pmid: N/A
An adaptive speech and channel coding scheme is described, applicable to the communication of intelligible speech over very narrowband, noisy channels. A fixed- channel bit rate of 1200 bits per second (b/s) is assumed and the channel Eb/N o can drop below 3 decibels. A family of speech coders, derived from a parent coder operating at 1200 b/s, is described which, when combined with a variable rate (punctured) convolutional code, yields an adaptive system capable of operating over a range of channel conditions. The locations of the channel Eb /No threshold points between the various schemes were derived through simulation.
Kenny, Owen P.; Nelson, Douglas J.; Bodenschatz, John S.; McMonagle, Heather
doi: 10.1177/003754979807000505pmid: N/A
The ability to distinguish spontaneous from non-spontaneous speech can prove helpful, such as in forensic evidence situations, sorting voice-mail responses from voice-mail menus, and automatic segmentation of spontaneous responses from prepared questions. The latter situation occurs when trying to create a database of spontaneous data from data of a speaker responding spontaneously to prepared prompts. This paper outlines and compares three methods for automatically classifying spontaneous and non- spontaneous speech, and presents the experimental results of the performance of all three methods, evaluated on high quality simulated data. All three methods are based on an analysis of the probability distributions of prosodic features extracted from speech signals.
Choi, Soo-Mi; Park, Joo-Young; Nam, Sang-Ah; Hong, Helen; Kim, Myoung-Hee
doi: 10.1177/003754979807000506pmid: N/A
In this paper, a teleconference system for medical image processing and orthopedic surgical simulation is presented. The system has been designed to integrate main functions for surgical teleconferencing using 3-D medical images for the user's convenience. The developed system, Teleconference System for Orthopedic Surgical Simulation (TOSS), includes three important components: the conference manager, the database manager and the surgical simulator. The conference manager controls conference flows and allows users to share workspace. The database manager maintains the conference database for patient data and conference data. The surgical simulator performs medical image processing for visualization and simulation. We find that the developed system can provide excellent support for cooperation in certain scenarios.
doi: 10.1177/003754979807000507pmid: N/A
This month CACI Products company announces three new add-on modules to COMNET III™, its award-winning object-oriented network simulation software. The three modules include: Application Profiler™, Circuit-Switched Module™, and Satellite and Mobile Module™. Application Profiler helps users predict the impact and performance for new client/server applications and architectures. Circuit-Switched Module helps users predict the impact and throughput of circuit-switched traffic over their networks. The third, Satellite and Mobile Module, helps users predict throughput and performance for wireless to wireline network integration, and is the focus of this article.
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