Barry M. G. Cheetham

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Delivering electronic goods over the Internet is one of the e-commerce applications that will proliferate in the coming years. Certified e-goods delivery is a process where valuable e-goods are exchanged for an acknowledgement of their reception. This paper proposes an efficient security protocol for certified e-goods delivery with the following features:(More)
Sinusoidal transform coding (STC) techniques model speech as the sum of sine-waves whose frequencies, amplitudes and phases are specified at regular intervals. To achieve a low-bit rate representation, only the spectral envelope is encoded and the phases are regenerated according to a minimum phase assumption. In this paper, the inaccuracy of the minimum(More)
Many types of parameters have been proposed for the evaluation of vocal cord abnormalities by speech waveform analysis. However, none of them taken separately allows a reliable assessment of the presence and the degree of abnormality. In this study we proposed to combine three different parameters which take into account different consequences of the(More)
Many low bit-rate speech coders represent the spectral envelope by an all-pole digital filter whose coefficients are calculated by a form of linear prediction (LP) analysis. The lower the bit-rate, the more critical will be the accuracy of the spectral analysis for achieving good quality speech. This paper compares four known techniques: a technique based(More)
Voice Activity Detectors (VAD's) are widely used in speech technology applications where available transmission or storage capacity is limited (e.g. mobile, DCME, etc.) and must be utilised with maximum economy. Modern day digital speech coding algorithms can provide toll quality speech at bit-rates as low as 8kbit/s (e.g. ITU-T G.729) and the use of a VAD(More)
To preserve the waveform shape and perceived quality of pitch and timescale modified sinusoidally modelled voiced speech, the phases of the sinusoids used to model the glottal excitation are made to add coherently at estimated pitch pulse locations. The glottal excitation is therefore made to resemble a pseudo-periodic impulse train, a quality essential for(More)