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

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

Sistemas de clasificación de blancos radar mediante métodos estadísticos y de inteligencia artificial

Premio Extraordinario de Doctorado 200

Sistemas de clasificación de blancos radar mediante métodos estadísticos y de inteligencia artificial

Premio Extraordinario de Doctorado 200

Cole parameter estimation from electrical bioconductance spectroscopy measurements

Several applications of Electrical Bioimpedance (EBI) make use of Cole parameters as base of their analysis, therefore Cole parameters estimation has become a very common practice within Multifrequency- and EBI spectroscopy. EBI measurements are very often contaminated with the influence of parasitic capacitances, which contributes to cause a hook-alike measurement artifact at high frequencies in the EBI obtained data. Such measurement artifacts might cause wrong estimations of the Cole parameters, contaminating the whole analysis process and leading to wrong conclusions. In this work, a new approach to estimate the Cole parameters from the real part of the admittance, i.e. the conductance, is presented and its performance is compared with the results produced with the traditional fitting of complex impedance to a depressed semi-circle. The obtained results prove that is feasible to obtain the full Cole equation from only the conductance data and also that the estimation process is safe from the influence capacitive leakage.© 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.QC 2012020

Experimental validation of a method for removing the capacitive leakage artifact from electrical bioimpedance spectroscopy measurements

Often when performing electrical bioimpedance (EBI) spectroscopy measurements, the obtained EBI data present a hook-like deviation, which is most noticeable at high frequencies in the impedance plane. The deviation is due to a capacitive leakage effect caused by the presence of stray capacitances. In addition to the data deviation being remarkably noticeable at high frequencies in the phase and the reactance spectra, the measured EBI is also altered in the resistance and the modulus. If this EBI data deviation is not properly removed, it interferes with subsequent data analysis processes, especially with Cole model-based analyses. In other words, to perform any accurate analysis of the EBI spectroscopy data, the hook deviation must be properly removed. Td compensation is a method used to compensate the hook deviation present in EBI data; it consists of multiplying the obtained spectrum, Z meas (ω), by a complex exponential in the form of exp(–jωTd). Although the method is well known and accepted, Td compensation cannot entirely correct the hook-like deviation; moreover, it lacks solid scientific grounds. In this work, the Td compensation method is revisited, and it is shown that it should not be used to correct the effect of a capacitive leakage; furthermore, a more developed approach for correcting the hook deviation caused by the capacitive leakage is proposed. The method includes a novel correcting expression and a process for selecting the proper values of expressions that are complex and frequency dependent. The correctness of the novel method is validated with the experimental data obtained from measurements from three different EBI applications. The obtained results confirm the sufficiency and feasibility of the correcting method.QC 20120209</p

The Parex Bank Advancement Measures of American Express Credit Card and Customer's Attitude Assessment.

Bakalaurā darbā tiek pētīts kādu lomu spēlē American Express kredītkaršu virzīšanas pasākumi patērētāju attieksmes veidošanā. Bakalaura darbs satur 5 daļas. Pirmajā daļā tiek aprakstīta patērētāju attieksmes būtība, to novērtēšanas metodes, kā arī attieksmes veidojošās American Express vērtības. Tālāk ir aplūkota American Express vēsture un to karšu veidi. Trešajā daļā tiek analizēta informācija par American Express kredītkaršu piedāvājumu Latvijā. Ceturtā darba daļa sastāv no pētāmajiem kredītkaršu virzīšanas pasākumiem Parex Bankā. Pēdējā daļā, ar anketēšanas palīdzību, tiek pētīta patērētāju attieksme par American Express kredītkaršu virzīšanas pasākumiem. Bakalaura darbs var būt izmantojams Parex bankas mārketinga speciālistiem, lai pilnveidotu pētāmās kartes virzīšanas pasākumus. Darbā ir 77 lappuses, 13 attēli, 7 tabulas un 3 pielikumi.Bachelor paper investigates what kind of part take American Express Credit Cards advancements measures to model customer`s attitude. Bachelor paper contains 5 parts. The first part devoted to customer`s attitude and it`s substance, valuation methodes, as well as attitude`s formative American Express values. The following part consider American Express Credit Cards history and all kinds of American Express Cards. Third part devoted to analysis of the information about American Express supply in Latvia. Fourth Bachelor paper part is devoted to regard Credit Cards advancement measures in Parex Bank. Last, with mediatize the customer`s attitude toward the American Express Credit Cards advancement measures is investigated. Bachelor paper permitted to be used by marketing specialists in Parex Bank, to improve these Cards advancement measures. Paper contains 77 peages, 13 images, 7 tables and 3 supplements

Detection and Classification of Measurement Errors in Bioimpedance Spectroscopy.

Bioimpedance spectroscopy (BIS) measurement errors may be caused by parasitic stray capacitance, impedance mismatch, cross-talking or their very likely combination. An accurate detection and identification is of extreme importance for further analysis because in some cases and for some applications, certain measurement artifacts can be corrected, minimized or even avoided. In this paper we present a robust method to detect the presence of measurement artifacts and identify what kind of measurement error is present in BIS measurements. The method is based on supervised machine learning and uses a novel set of generalist features for measurement characterization in different immittance planes. Experimental validation has been carried out using a database of complex spectra BIS measurements obtained from different BIS applications and containing six different types of errors, as well as error-free measurements. The method obtained a low classification error (0.33%) and has shown good generalization. Since both the features and the classification schema are relatively simple, the implementation of this pre-processing task in the current hardware of bioimpedance spectrometers is possible