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This letter describes a novel window‐based approach to FIR filter design. The window is constructed on the use of equispaced Gaussian basis functions. Unlike other known window‐based methods that do not allow for a satisfactory degree of control over band edges, the proposed method affords very good solution for controlling critical frequencies. In addition, the proposed window method is easier to implement than Kaiser's and affords a better passband flatness than any known design approach. It also yields stopband attenuations and control of critical frequencies which turn out to be very close to those obtainable with Parks–McClellan's method. So the proposed GBR window approach appears to be a significant step forward. [ABSTRACT FROM AUTHOR]

The paper presents an adaptive system for Voiced/Unvoiced (V/UV) speech detection in the presence of background noise. Genetic algorithms were used to select the features that offer the best V/UV detection according to the output of a background Noise Classifier (NC) and a Signal-to-Noise Ratio Estimation (SNRE) system. The system was implemented, and the tests performed using the TIMIT speech corpus and its phonetic classification. The results were compared with a nonadaptive classification system and the V/UV detectors adopted by two important speech coding standards: the V/UV detection system in the ETSI ES 202 212 v1.1.2 and the speech classification in the Selectable Mode Vocoder (SMV) algorithm. In all cases the proposed adaptive V/UV classifier outperforms the traditional solutions giving an improvement of 25% in very noisy environments. [ABSTRACT FROM AUTHOR]

The performance of traditional biometric identification systems is, as yet, unsatisfactory in certain applications. For this reason, other physiological or behavioral characteristics have recently been considered, using new electrical or physical signals linked to a person's vital signs. This paper examines the biometric characteristics of phonocardiogram (PCG) signals from cardiac auscultation. The idea is that PCG signals have specific individual characteristics that can be taken into consideration as a physiological sign used in a biometric system. More specifically, the paper proposes a preliminary study related to the identification of individuals via frequency analysis of cardiac sounds. The results, obtained using a database containing several heart sound recordings from 20 different people, confirm the biometric properties of PCG signals, which can thus be included among the physiological signs used by an automatic identification system. [ABSTRACT FROM PUBLISHER]

An adaptive system for Voiced/Unvoiced (V/UV) speech detection in the presence of background noise is presented. The results were compared with a non-adaptive classification system and the V/UV detectors adopted by three important speech coding standards: LPC10, ITU-T G. 723.1 and ETSI AMR. In all cases the adaptive V/UV classifier outperformed the traditional solutions. [ABSTRACT FROM AUTHOR]

The introduction of new variable bit rate (VBR) speech coders has opened up new perspectives for the implementation of adaptive voice over IP (AVoIP) systems. The paper compares different VBR speech coding techniques in a scenario in which the rate of the single sources is dynamically adapted to the workload conditions. The coders compared are the AMR, the M3 R and the G.729. Using source and rate control mechanism models, performance is evaluated in terms of loss probability, offered throughput and mean CMOS with varying numbers of sources. The use of header compression mechanisms is also evaluated [ABSTRACT FROM PUBLISHER]