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Publications (140)
Many individuals experience hearing problems that are hidden under a normal audiogram. This not only impacts on individual sufferers, but also on clinicians who can offer little in the way of support. Animal studies using invasive methodologies have developed solid evidence for a range of pathologies underlying this hidden hearing loss (HHL), inclu...
Auditory evoked potentials can be estimated by synchronous averaging when the responses to the individual stimuli are not overlapped. However, when the response duration exceeds the inter-stimulus interval, a deconvolution procedure is necessary to obtain the transient response. The iterative randomized stimulation and averaging and the equivalent...
Objective:
To present randomised stimulation level (RSL) - a stimulation paradigm in which the level of the stimuli is randomised, rather than presented sequentially as in the conventional paradigm.
Design:
The value of RSL was evaluated by (i) comparing the morphology of auditory brainstem responses (ABRs) elicited by the conventional and RSL p...
Phase-resolved luminescence chemical sensors provide the analyte determination based on the estimation of the luminescence lifetime. The lifetime is estimated from an analysis of the amplitudes and/or phases of the excitation and emission signals at one or several modulation frequencies. This requires recording both the excitation signal (used to m...
In this work, we propose a new model describing the relationship between the analyte concentration and the instrument response in photoluminescence sensors excited with modulated light sources. The concentration is modeled as a polynomial function of the analytical signal corrected with an exponent, and therefore the model is referred to as a polyn...
Auditory evoked potentials (AEPs) include the auditory brainstem response (ABR), middle latency response (MLR), and cortical auditory evoked potentials (CAEPs), each one covering a specific latency range and frequency band. For this reason, ABR, MLR, and CAEP are usually recorded separately using different protocols. This article proposes a procedu...
Infrasound is an increasingly popular tool for volcano monitoring, providing insights of the unrest by detecting and characterizing acoustic waves produced by volcanic processes, such as explosions, degassing, rockfalls, and lahars. Efficient event detection from large infrasound databases gathered in volcanic settings relies on the availability of...
The iterative randomized stimulation and averaging (IRSA) method was proposed for recording evoked potentials when the individual responses are overlapped. The main inconvenience of IRSA is its computational cost, associated with a large number of iterations required for recovering the evoked potentials and the computation required for each iterati...
We present an S-phase picking algorithm for volcano-tectonic earthquakes (VTs), based on the changes of frequency and amplitude expected in the plane transverse to the ray direction at S-phase arrival. A measure of these changes, called spectral dissimilarity, is proposed. Picking is performed in a particular waveform transformation that underlines...
In this work we present a method to estimate the spatial orientation of a mobile node using the time-of-flight (TOF) and the signal strength (RSSI) of the ultrasound signals emitted by a set of fixed reference nodes with known positions. The orientation of the node is estimated from the power level of the received signal by applying a power-loss mo...
In this work we present the architecture of a modular, portable and low-cost phosphorescence instrument for accurate determination of gaseous oxygen. This instrument implements a novel multifrequency phase-modulation method for luminescence spectroscopy based on a rectangular-wave modulated excitation source with a short duty cycle. From the Fast F...
Seismic coda measurements retrieve parameters linked to the physical characteristics of rock volumes illuminated by high frequency scattered waves. Space weighting functions (SWF) and kernels are different tools that model the spatial sensitivity of coda envelopes to scattering and absorption anomalies in these rock matrices, allowing coda-wave att...
Este trabajo desarrolla una propuesta didáctica para introducir actividades de programación por ordenador en la resolución de problemas de Física. Tal propuesta persigue un doble objetivo: por una parte facilitar, a través de la programación de simulaciones de Física, la asimilación de los contenidos de esta materia y, por otra, iniciar a los alumn...
As optoelectronics and microelectronics have evolved, new alternatives in phosphorescence measurement instrumentation have been recently proposed. In this chapter we present the phosphorescent system as a linear system (described by a linear differential equation), whose parameters depend on the oxygen concentration to be determined. Under this per...
En los últimos años las tecnologías TIC se han ido incorporando en los diferentes ámbitos de la enseñanza, desde las pizarras electrónicas para las clases magistrales hasta el uso de tabletas para la visualización de libros docentes en formato electrónico. De hecho, resulta cada vez más frecuente que los docentes empleen sus portátiles para present...
Objective: Artifact reduction in electroencephalogram (EEG) signals is usually
necessary to carry out data analysis appropriately. Despite the large amount of
denoising techniques available with a multichannel setup, there is a lack of e�cient
algorithms that remove (not only detect) blink-artifacts from a single channel EEG,
which is of interest i...
This work presents a novel approach to automatic detection of long period events (LP) in continuous seismic records. Without any supervised learning, the proposal is based on a simple processing to search for the LP characteristic shape, duration, and band of activity. Continuous raw signals from the seismometer are first filtered into three freque...
A method for optimally combining multifrequency information in phase-resolved luminescence spectroscopy using rectangular-wave signals is proposed to improve the accuracy in the determination of the analyte concentration. From the rectangular-wave signal, phase-shift- and modulation-factor-based apparent lifetimes are estimated at each harmonic ind...
XIII Conference on Optical Chemical Sensors and Biosensors
The accurate estimation of the arrival time of seismic waves or picking is a problem of major interest in seismic research given its relevance in many seismological applications, such as earthquake source location and active seismic tomography. In the last decades, several automatic picking methods have been proposed with the ultimate goal of imple...
The complex [Cu(xanpthos)(dmp)][PF6] (dmp = 2,9-dimethyl-1,10-phenanthroline) in a nanostructured metal oxyde matrix shows better sensitivity to oxygen (KSV = 9.74 ± 0.87 kPa–1 between 0 and 1 kPa pO2 and 5.59 ± 0.15 kPa–1 between 0 and 10 kPa pO2) than cyclometallated iridium complexes in the same conditions.
Randomized stimulation and averaging (RSA) allows auditory evoked potentials (AEPs) to be recorded at high stimulation rates. This method does not perform deconvolution and must therefore deal with interference derived from overlapping transient evoked responses. This paper analyzes the effects of this interference on auditory brainstem responses (...
Los potenciales evocados auditivos del tronco cerebral son una herramienta de evaluación objetiva de la audición ampliamente utilizada en hospitales y clínicas de todo el mundo. La evaluación y detección automática de parámetros característicos de estas señales pueden dar lugar a un diagnóstico muy preciso. El uso de métodos automáticos favorece es...
El registro de potenciales evocados auditivos se utiliza en hospitales y clínicas de todo el mundo como método de detección de patologías auditivas y para estimar de forma objetiva el umbral de audición. Además, el registro de estas señales es utilizado en numerosos centros de investigación para comprender y modelar los diferentes mecanismos involu...
Abstract Recording auditory evoked responses (AER) is done not only in hospitals and clinics worldwide to detect hearing impairments and estimate hearing thresholds, but also in research centers to understand and model the mechanisms involved in the process of hearing. This paper describes a high-performance, flexible, and inexpensive AER recording...
We propose a novel multifrequency phase-modulation method for luminescence spectroscopy using a rectangular-wave modulated excitation source with a short duty cycle. It is used for obtaining more detailed information about the luminescence system: the information provided by different harmonics allows estimating a model for describing the global fr...
The recording of the auditory brainstem response (ABR) is used worldwide for hearing screening purposes. In this process, a precise estimation of the most relevant components is essential for an accurate interpretation of these signals. This evaluation is usually carried out subjectively by an audiologist. However, the use of automatic methods for...
This letter presents a novel picking algorithm which allows an automated determination of the P-phase onset time. The algorithm includes an adaptive multiband processing and noise-reduction techniques to allow a confident onset time estimation in signals strongly affected by background and/or nonstationary noise processes. Results using a set of 37...
This paper analyzes the fast and slow mechanisms of adaptation through a study of latencies and amplitudes on ABR recorded at high stimulation rates using the randomized stimulation and averaging (RSA) technique.
The RSA technique allows a separate processing of auditory responses, and is used, in this study, to categorize responses according to th...
Seismic activity is one of the main precursors of volcanic eruptions as it usually increases before crises. The material Failure Forecast Method (FFM) is the most common approach used for eruption prediction. It is based on empirical power laws applied to observables which can be the mean level of seismic signal, the rate of occurrence or the energ...
The accurate and real-time measurement of low and ultra-low concentrations of oxygen using non-invasive methods is a necessity for a multitude of applications, from brewing beer to developing encapsulating barriers for optoelectronic devices. Current optical methods and sensing materials often lack the necessary sensitivity, signal intensity, or st...
This paper describes the TELIAMADE system, a new indoor positioning system based on time-of-flight (TOF) of ultrasonic signal to estimate the distance between a receiver node and a transmitter node. TELIAMADE system consists of a set of wireless nodes equipped with a radio module for communication and a module for the transmission and reception of...
This paper presents the design and evaluation of an ultrasonic time-of-flight (TOF) measurement system in the context of a smart sensor wireless network. In particular, the ZigBee protocol is used for data transmission and synchronization purposes. Low-cost and low-power restrictions are taken into account in the design. A synchronous measurement s...
This paper discusses the problem of accurate time synchronization of wireless sensor networks (WSNs) used in applications in which a physical phenomenon must be monitored through periodical sampling. In some applications incorrect time synchronization can significantly degrade the system precision. This is for example the case of local positioning...
In this paper we present an open and low-cost optical-fiber measurement system for the optical detection of oxygen. A multifrequency phase-resolved method is proposed as the measurement technique in order to evaluate the oxygen-concentration-dependent phase-shift (or luminescence lifetime). Such evaluation is based on the operating principles of qu...
We propose a method identifying candidates for active compounds in vegetal extracts. From a collection of samples, the method requires, for each sample, a HPLC-MS analysis and a measurement of the activity. By applying a correlation analysis between the activity and the chromatographic area for each interval of elution time and m/z ratio, the peaks...
The stimulation levels programmed in cochlear implant systems are affected by an evolution since the first switch-on of the processor. This study was designed to evaluate the changes in stimulation levels over time and the relationship between post-implantation physiological changes and with the hearing experience provided by the continuous use of...
The recording of auditory brainstem response (ABR) at high stimulation rates is of great interest in audiology. It allows a more accurate diagnosis of certain pathologies at an early stage and the study of different mechanisms of adaptation. This paper proposes a methodology, which we will refer to as randomized stimulation and averaging (RSA) that...
Objective:
It is well known that a proper fitting of the cochlear implant processor is relevant to provide good quality in speech perception. The aim of this study is to extract statistical information to be applied for fitting the processor.
Methods:
This study is based on the programming maps of 121 patients, aged from 18 months to 68 years at...
This letter assesses an improved equalization transformation for robust speech recognition in noisy environments. The proposal is an evolution of the parametric approximation to Histogram Equalization named PEQ into a two-step algorithm dealing separately with environmental and acoustic mismatch. A first parametric equalization is done to eliminate...
Brainstem auditory evoked response (BAER) signals represent the electrical activity of the auditory brainstem associated with a stimulus. The study of BAER at high stimulation rates is of great interest in the field of audiology since it presents several advantages: the reduction of the recording time, an earlier diagnosis of certain neural disease...
Many protocols for newborn and infant hearing screening incorporate the acquisition of Brainstem Auditory Evoked Responses (BAER). This evoked potential represents the neural activity associated with the brainstem in response to a sound stimulus. The biological response waveform is characterized by a series of positive waves that occur during the f...
Feature extraction is a critical element in automatic pattern classification. In this letter, we propose different sets of parameters for classification of volcano-seismic signals, and the discriminative feature selection (DFS) method is applied for selecting the minimum number of features containing most of the discriminative information. We have...
This paper proposes TELIAMADE (an indoor location system based on ultrasonic and radiofrequency signals) to be used as a teaching tool in the context of Telecommunication Engineering. Due to its simple design, the versatility of its configuration and the characteristics of the involved signals, TELIAMADE is an appropriate tool for teaching basic as...
This paper presents the new features of the TELIAMADE indoor location system. The new version uses symmetric nodes able to operate as both transmitters and receivers of ultrasonic signals. Sensor nodes implement the ZigBee protocol. The network coordinator is connected to a PC using a standard RS232 interface and acts as the network gateway. A simp...
This E-book is a collection of articles that describe advances in speech recognition technology. Robustness in speech recognition refers to the need to maintain high speech recognition accuracy even when the quality of the input speech is degraded, or when the acoustical, articulate, or phonetic characteristics of speech in the training and testing...
Objective: The aim of this work is to present a longitudinal study of the refractory properties of the population of neurons involved in the generation of the evoked compound action potential (ECAP). Materials and Methods: The refractory properties of 12 subjects implanted with the Med-El Pulsar CI(100) cochlear implant system have been examined by...
Brainstem Auditory Evoked Response (BAER) represents the electrical activity of the auditory nerve associated to a stimulus. The recording process of this signal is a challenging milestone that requires the development of multidisciplinary competences. Current medical devices able to record BAER are expensive and are not usually flexible enough for...
Auditory brainstem response represents the neural activity associated with the auditory brainstem function in response to a sound stimulus. Many protocols for early detection of hearing loss in infants and toddlers incorporate the acquisition of the auditory brainstem response, since it provides information regarding auditory function and hearing s...
In this paper we present TELIAMADE, an indoor location system based on ultrasonic and RF. TELIAMADE consists of a set of reference nodes (transmitters) controlled from a coordinator node using the ZigBee protocol. The position of the mobile node (receiver) is obtained by triangulation using measurements of time of flight of the ultrasonic signal em...