This paper intends to summarize some of the robust feature extraction and acoustic modeling technologies used at Multitel, together with their assessment on some of the ETSI Aurora reference tasks. Ongoing work and directions for further research are also presented. For feature extraction (FE), we are using PLP coefficients. Additive and convolutional noise are addressed using a cascade of spec...

In the last years, CDMA has been established as a standard multiple access scheme in mobile radio communications. However, high spectral efficiency can only be achieved by applying multi-user detection schemes combatting the inherent multi-user interference. Since the optimum maximum likelihood approach is far to complex for practical implementations, suboptimum iterative strategies are applied...

Factorization of large numbers has been a constant source of interest in cryptanalysis. The fastest known algorithm for factoring large numbers is the Number Field Sieve (NFS). The two most time consuming phases of NFS are Sieving and Matrix Step. In this paper, we propose an efficient way of implementing the Matrix step in reconfigurable hardware. Our solution is based on the MeshRouting metho...

Solutions proposed in bibliography for multiple user allocation on the sub-bands of an OFDM system, adopting multiple antennas, require highly computational effort and consider delay insensitive applications. Our approach tends to overcome all these limitations relaxing some hypothesis in order to give a feasible solution. The proposed algorithm can be applied to a real multiple antenna OFDM sy...

In this paper, we present the work done in language identification for two air traffic control speech recognizers, one for continuous speech and the other one for a command interface. The system is able to distinguish between Spanish and English. We will confirm the advantage of using PPRLM over PRLM. All previous studies show that PPRLM is the technique with the best performance despite of its...

This paper proposes a voice activity detector (VAD) based on the complex Laplacian model. With the use of a goodness-of-fit (GOF) test, it is discovered that the Laplacian model is more suitable to describe noisy speech distribution than the conventional Gaussian model. The likelihood ratio (LR) based on the Laplacian model is computed and then applied to the VAD operation. According to the exp...

The Synface project is developing a synthetic talking face to aid the hearing impaired in telephone conversation. This report investigates the gain in intelligibility from the synthetic talking head when controlled by hand-annotated speech. Audio from Swedish, English and Dutch sentences was degraded to simulate the information losses that arise in severe-to-profound hearing impairment. 12 norm...

We consider a distributed power control scheme in a Spread Spectrum (SS) wireless ad hoc network, in which each user announces a price that reflects his current interference level. Given these prices, we present an asynchronous distributed algorithm for updating power levels, and provide conditions under which this algorithm converges to an optimal power allocation. We relate this algorithm to ...

This paper describes some experiments with pronunciation modeling for spontaneous speech in European Portuguese. The transducer framework provides an elegant way to combine a pronunciation lexicon of canonical forms with alternative pronunciation rules. The main phonological aspects that the rules are intended to cover are: vowel devoicing, deletion and coalescence, voicing assimilation, and si...