Fusion Methods for Biosignal Analysis: Theory and Applications

Salazar Afanador, A.; Zarzoso, V.; Rosa-Zurera, M.; Vergara Domínguez, L. (2017). Fusion Methods for Biosignal Analysis: Theory and Applications. Computational Intelligence and Neuroscience. (1):1-2. doi:10.1155/2017/7152546S12

Generation of optical reference signals robust to diffractive effects

In grating measurement systems, a reference signal is needed to achieve an absolute measurement of the position. The zero reference signals are normally obtained illuminating two identical superimposed zero reference codes (ZRCs) and registering the transmitted light by means of a photodiode. As one ZRC moves with respect to the other, the two codes overlap and the signal registered is the autocorrelation of the ZRC transmittance. In high resolution systems, the diffraction effects degrade the geometrical shadow of the first ZRC as it propagates to the second one. As a result, the autocorrelation is also degraded and the amplitude of the reference signal is greatly reduced. In this letter, we present a method for designing ZRCs with minimum diffractive effects. The method is based on the optimization of ZRCs by means of a genetic algorithm

DVB-T Receiver Independent of Channel Allocation, with Frequency Offset Compensation for Improving Resolution in Low Cost Passive Radar.

In this article, a commercial low cost solution for increasing DVB-T based passive radar (also referred to as passive coherentlocation)robustnesswith respectto channel allocation and range resolution, is designed. IDEPAR demonstrator is updated to include a new recording system in charge of DVB-T channels reallocation. The use of commercial hardware introduces frequency mismatching between acquired channels that compromises system operation. To face channel frequency alignment, fulfilling the requirements imposed by the high Doppler resolution typical of passive radars, a novel compensation algorithm is proposed, based on the minimization of signal dispersion in the Cross-Ambiguity Function domain. The well-known cyclic prefix van de Beek method is used as reference. Results show an increase in target signal to interference ratio and detection performances, as well as a reduction of clutter dispersion when the novel proposed algorithm is applied. The low cost solution is also compared to a high performance one capable of acquiring a wide bandwidth of sparse DVB-T channels, and performing channel reallocation by digital signal processing. Results show that both systems reached similar performances in terms of range resolution and SNR improvement

Optimal design of optical reference signals by use of a genetic algorithm

A new technique for the generation of optical reference signals with optimal properties is presented. In grating measurement systems a reference signal is needed to achieve an absolute measurement of the position. The optical signal is the autocorrelation of two codes with binary transmittance. For a long time, the design of this type of code has required great computational effort, which limits the size of the code to ~30 elements. Recently, the application of the dividing rectangles (DIRECT) algorithm has allowed the automatic design of codes up to 100 elements. Because of the binary nature of the problem and the parallel processing of the genetic algorithms, these algorithms are efficient tools for obtaining codes with particular autocorrelation properties. We design optimum zero reference codes with arbitrary length by means of a genetic algorithm enhanced with a restricted search operator

Improving speech intelligibility in hearing aids. Part II: Quality assessment

[EN] Subjective tests are the most reliable methods for quantifying the perceived speech intelligibility, but the process to perform these tests usually is time consuming and cost expensive. For this reason, different objective measures have been proposed in the literature to evaluate the intelligibility and/or quality of speech in such a way that cooperation of human listeners is not necessary. In this paper, we describe a wide range of subjective tests reported in the literature, focusing on those proposed to evaluate speech intelligibility of Spanish language, not only for normal hearing listeners, but for hearing impaired as well. Afterwards we summarize the most common objective measures of speech quality, and finally we perform a comparison between them and some subjective speech intelligibility tests. In the subjective tests, clean Spanish speech material has been contaminated with different real background noises: cafeteria and outside traffic noise. Results show that Short-Time Objective Intelligibility (STOI) and Perceptual Evaluation of Speech Quality (PESQ) indices present a better correlation and a lower mean square error when predicting intelligibility compared to other objective measures tested.This work has been supported by European Union ERDF and Spanish Government through TEC2012-38142-C04 project, and Generalitat Valenciana through PROMETEOII/2014/003 project. Participation of author A. Padilla has been supported by a postdoctoral fellowship from Conacyt (Mexico). The authors wish to acknowledge Prof. Felipe Orduña for his insightful comments that contributed to improve the manuscript, and to everyone who participated in the listening tests.Padilla, A.; Piñero Sipán, MG.; Diego Antón, MD.; Ferrer Contreras, M.; González Téllez, A.; Ayllón, D.; Gil Pita, R.... (2014). Improving speech intelligibility in hearing aids. Part II: Quality assessment. Waves. 6:73-85. http://hdl.handle.net/10251/57900S7385

Improving speech intelligibility in hearing aids. Part I: Signal processing algorithms

[EN] The improvement of speech intelligibility in hearing aids is a traditional problem that still remains open and unsolved. Modern devices may include signal processing algorithms to improve intelligibility: automatic gain control, automatic environmental classification or speech enhancement. However, the design of such algorithms is strongly restricted by some engineering constraints caused by the reduced dimensions of hearing aid devices. In this paper, we discuss the application of state-of-theart signal processing algorithms to improve speech intelligibility in digital hearing aids, with particular emphasis on speech enhancement algorithms. Different alternatives for both monaural and binaural speech enhancement have been considered, arguing whether they are suitable to be implemented in a commercial hearing aid or not.This work has been funded by the Spanish Ministry of Science and Innovation, under project TEC2012-38142-C04-02.Ayllón, D.; Gil Pita, R.; Rosa Zurera, M.; Padilla, L.; Piñero Sipán, MG.; Diego Antón, MD.; Ferrer Contreras, M.... (2014). Improving speech intelligibility in hearing aids. Part I: Signal processing algorithms. Waves. 6:61-71. http://hdl.handle.net/10251/57901S6171

Studing audition in fossil hominins: a new approach to the evolution of language?

The evolution of human language is one of the oldest questions inpaleoanthropology. Nevertheless, many previous attempts to approachthis question have not yielded informative results since they are oftenbased on anatomical features whose role in speech production in modernhumans is unclear or whose functional implications in fossil specimensare difficult to assess. We take a new approach to this question bystudying the evolution of audition. Human hearing differs from that ofchimpanzees and other primate taxa in maintaining a widened bandwidthof heightened sensitivity between 1-8 kHz, a region that contains relevantacoustic information in spoken language. Comparative analysis ofprimate audiograms suggests that this represents a unique derived featurein modern humans. Knowledge of the auditory capacities in our fossilhuman ancestors could greatly enhance the understanding of when thishuman pattern emerged during the course of our evolutionary history.Here we present a comprehensive approach to this question, onlyrarely addressed in human evolutionary studies. We have analyzed theauditory capacities in five fossil human specimens from the MiddlePleistocene site of the Sima de los Huesos (SH) in the Sierra deAtapuerca of Spain. The results demonstrate that the Atapuerca (SH)hominins resemble modern humans in showing a widened bandwidth ofheightened sensitivity between 1-5 kHz, a frequency range whichoverlaps the range of frequencies emitted during spoken language. At thesame time, both modern humans and the Atapuerca (SH) hominins differfrom chimpanzees in showing a heightened sensitivity to the highconsonant area (approximately 3-5 kHz) of the so-called "speechbanana", a frequency range associated with consonant production inhuman spoken language.The presence of a modern human auditory pattern in the Atapuercahominins suggests that these Middle Pleistocene humans alreadypossessed the anatomical features of the outer and middle ear that supportthe perception of human spoken language. Given the intuitive, butdifficult to quantify, link between sound perception and vocal productionin animals, the study of auditory capacities may have implications for theemergence of language in our fossil human ancestors. Although the studyof audition is an indirect approach to the question of speech capacity infossil specimens, the results of the present study are consistent with otherrecent suggestions for the presence of some form of spoken language inthe genus Homo prior to the appearance of our own species, Homosapiens

Sea Clutter Reduction and Target Enhancement by Neural Networks in a Marine Radar System

The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction system. The developed experiments show promising results characterized by different subjective (visual analysis of the processed radar images) and objective (clutter reduction, target enhancement and signal-to-clutter ratio improvement) criteria. Moreover, a deep study of the NN structure is done, where the low computational cost and the high processing speed of the proposed NN structure are emphasized