Exploring the characteristics of analytic decomposition of speech signals

This paper investigates the properties of analytic transformation of speech into envelope and phase functions. The envelope is shown to evolve slowly with the pitch of the input speech, whilst the phase consists of two components; one evolving slowly with pitch and another that exhibits a more rapid evolution. We investigate decomposing the phase component further using two distinct methods: (a) filtering of the phase in the pitch evolutionary direction and (b) performing a second analytic decomposition of the phase into secondary envelope and phase components. To examine the characteristics of the pitch cycle evolution, the analytic transform is employed in a waveform interpolation (WI) coding structure. The two phase decompositions are then analysed with particular emphasis on quantisation sensitivity and the required transmission rate. Results indicate that the analytic decomposition may offer a degree of scalability to speech coders, especially when employed in coders that exploit pitch evolution such as WI

Low rate WI SEW representation using a REW-implicit pulse model

Reducing the bit rate of waveform interpolation speech coders while maintaining the perceptual quality has been the focus of a great deal of research. This letter proposes a new method of slowly evolving waveform (SEW) quantization specifically targeted at low rate coding. The proposed method uses a pulse model whose parameters are implicitly contained in the quantized rapidly evolving waveform (REW) parameters, thus requiring no bits for transmission. Results indicate no degradation in perceptual speech quality when compared to that of the existing SEW quantization method. This retention of perceptual quality is in spite of a 12% reduction in the overall coder bit rate

An analysis of the limitations of blind signal separation application with speech

Blind Signal Separation (BSS) techniques are commonly employed in the separation of speech signals, using Independent Component Analysis (ICA) as the criterion for separation. This paper investigates the viability of employing ICA for real-time speech separation (where short frame sizes are the norm). The relationship between the statistics of speech and the assumption of statistical independence (at the core of ICA) is examined over a range of frame sizes. The investigation confirms that statistical independence is not a valid assumption for speech when divided into the short frames appropriate to real-time separation. This is primarily due to the quasi-stationary nature of speech over the temporal short term. We conclude that employing ICA for real-time speech separation will always result in limited performance due to a fundamental failure to meet the strict assumptions of ICA

Scalable speech coding spanning the 4 Kbps divide

This paper examines a scalable method for coding the LP residual. The scalable method is capable of increasing the accuracy of the reconstructed speech from a parametric representation at low rates to a more accurate waveform matched representation at higher rates. The method entails pitch length segmentation, decomposition into pulsed and noise components and modeling of the pulsed components using a fixed shape pulse model in a closed-loop, Analysis by Synthesis system. Subjective testing is presented that indicates that in addition to the AbyS modeling, the pulse parameter evolution must be constrained in synthesis. Results indicate that this proposed method is capable of producing perceptually scalable speech quality as the bit rate is increased through 4 kbps

LES NOYAUX DE TRANSITION 189Ir ET 187Ir SONT-ILS TRIAXIAUX ?

Les niveaux excités des noyaux 189Ir et 187Ir ont été étudiés par réaction (α, 2nγ) sur le faisceau du cyclotron de Grenoble. Les schémas détaillés qui ont été établis mettent en évidence : 1) des états de parité positive qui s'interprètent comme appartenant aux deux bandes 3/2+ | 402 | (fondamental) et 1/2+ | 400 | mélangées par interaction de Coriolis (noyaux a symétrie axiale de déformation positive) ; 2) une bande découplée construite sur un état 9/2- (h 9/2) décrite de manière équivalente par un modèle à symétrie axiale et déformation positive ou par un modèle a particule-plus-rotor asymétrique ; 3) une structure complexe pour les niveaux de parité négative associés à l'isomère 11/2- (h 11/2). Ce système est correctement prédit par le modèle à rotor asymétrique

The Modified Weighted Slab Technique: Models and Results

In an attempt to understand the source and propagation of galactic cosmic rays we have employed the Modified Weighted Slab technique along with recent values of the relevant cross sections to compute primary to secondary ratios including B/C and Sub-Fe/Fe for different galactic propagation models. The models that we have considered are the disk-halo diffusion model, the dynamical halo wind model, the turbulent diffusion model and a model with minimal reacceleration. The modified weighted slab technique will be briefly discussed and a more detailed description of the models will be given. We will also discuss the impact that the various models have on the problem of anisotropy at high energy and discuss what properties of a particular model bear on this issue.Comment: LaTeX - AASTEX format, Submitted to ApJ, 8 figures, 20 page

High-spin states in 232U investigated with the 232Th(α, 4nγ) reaction

The ground-state rotational band of 232U is established up to Iπ = 16+ (tentatively 18+) through a study of the 232Th(α, 4nγ) reaction. Conversion electron spectroscopy is found to be especially useful in circumventing the difficulties caused by strong fission competition