Auditory-inspired morphological processing of speech spectrograms: applications in automatic speech recognition and speech enhancement

New auditory-inspired speech processing methods are presented in this paper, combining spectral subtraction and two-dimensional non-linear filtering techniques originally conceived for image processing purposes. In particular, mathematical morphology operations, like erosion and dilation, are applied to noisy speech spectrograms using specifically designed structuring elements inspired in the masking properties of the human auditory system. This is effectively complemented with a pre-processing stage including the conventional spectral subtraction procedure and auditory filterbanks. These methods were tested in both speech enhancement and automatic speech recognition tasks. For the first, time-frequency anisotropic structuring elements over grey-scale spectrograms were found to provide a better perceptual quality than isotropic ones, revealing themselves as more appropriate—under a number of perceptual quality estimation measures and several signal-to-noise ratios on the Aurora database—for retaining the structure of speech while removing background noise. For the second, the combination of Spectral Subtraction and auditory-inspired Morphological Filtering was found to improve recognition rates in a noise-contaminated version of the Isolet database.This work has been partially supported by the Spanish Ministry of Science and Innovation CICYT Project No. TEC2008-06382/TEC.Publicad

Beyond the merchant and the clergyman: assessing moral claims about development cooperation

This article proposes to move beyond the categories of altruism and self-interest in the analyses of the motives for development cooperation. This opposition ignores the inherently moral nature of development policy. The article illustrates the shortcomings of such a perspective by tracing the metaphor of the merchant and the clergyman as archetypical figures shaping Dutch development policy. Through these images the suggestion of an opposition between moral and amoral motives in the history of development has gained a strong foothold within the interplay of scholars, policy makers and public opinion. We go on to assess claims about economy, security, solidarity, prestige and guilt, and ecology, which have been brought forward to legitimise Dutch foreign aid. This analysis calls for research on the dynamics of the transnational exchanges of ideas, interests and expectations, especially during episodes when the moral validity of policy has been explicitly contested

A Dependence between Average Call Duration and Voice Transmission Quality: Measurement and applications

This contribution deals with the estimation of the relation between speech transmission quality and average call duration for a given network and portfolio of customers. It uses non-intrusive speech quality measurements on live speech calls. The basic idea behind this analysis is an expectation that the average call duration is higher for calls of a good quality since users are less disturbed during their conversation by transmission impairments. Both traditional and state of the art methods for non-intrusive speech transmission quality measurements and also for call duration monitoring are briefly described and two basic ways of the dependency analysis are shown. The relations for result uncertainty estimation are derived. A numerical example is given based on a limited training database that is constructed on the basis of real network data. Finally, potential applications are presented and discussed. The first results indicate that in the low to medium quality range (Mean Opinion Scores between 1 and 3) the call duration increases with increasing speech quality