Binaural pre-processing for contralateral sound field attenuation and improved speech-in-noise recognition

Understanding speech presented in competition with other sounds can be challenging. Here, we reason that in free-field settings, this task can be facilitated by attenuating the sound field contralateral to each ear and propose to achieve this by linear subtraction of the weighted contralateral stimulus. We mathematically justify setting the weight equal to the ratio of ipsilateral to contralateral head-related transfer functions (HRTFs) averaged over an appropriate azimuth range. The algorithm is implemented in the frequency domain and evaluated technically and experimentally for normal-hearing listeners in simulated free-field conditions. Results show that (1) it can substantially improve the signal-to-noise ratio (up to 30 dB) and the short-term objective intelligibility in the ear ipsilateral to the target source, particularly for maskers with speech-like spectra; (2) it can improve speech reception thresholds (SRTs) for sentences in competition with speech-shaped noise by up to 8.5 dB in bilateral listening and 10.0 dB in unilateral listening; (3) for sentences in competition with speech maskers and in bilateral listening, it can improve SRTs by 2 to 5 dB, depending on the number and location of the masker sources; (4) it hardly affects virtual sound-source lateralization; and (5) the improvements, and the algorithm's directivity pattern depend on the azimuth range used to calculate the weights. Contralateral HRTF-weighted subtraction may prove valuable for users of binaural hearing devices

Temporal Effects on Monaural Amplitude-Modulation Sensitivity in Ipsilateral, Contralateral and Bilateral Noise

The amplitude modulations (AMs) in speech signals are useful cues for speech recognition. Several adaptation mechanisms may make the detection of AM in noisy backgrounds easier when the AM carrier is presented later rather than earlier in the noise. The aim of the present study was to characterize temporal adaptation to noise in AM detection. AM detection thresholds were measured for monaural (50 ms, 1.5 kHz) pure-tone carriers presented at the onset ('early' condition) and 300 ms after the onset ('late' condition) of ipsilateral, contralateral, and bilateral (diotic) broadband noise, as well as in quiet. Thresholds were 2-4 dB better in the late than in the early condition for the three noise lateralities. The temporal effect held for carriers at equal sensation levels, confirming that it was not due to overshoot on carrier audibility. The temporal effect was larger for broadband than for low-band contralateral noises. Many aspects in the results were consistent with the noise activating the medial olivocochlear reflex (MOCR) and enhancing AM depth in the peripheral auditory response. Other aspects, however, indicate that central masking and adaptation unrelated to the MOCR also affect both carrier-tone and AM detection and are involved in the temporal effects

A Binaural Cochlear Implant Sound Coding Strategy Inspired by the Contralateral Medial Olivocochlear Reflex

[EN] Objectives: In natural hearing, cochlear mechanical compression is dynamically adjusted via the efferent medial olivocochlear reflex (MOCR). These adjustments probably help understanding speech in noisy environments and are not available to the users of current cochlear implants (CIs). The aims of the present study are to: (1) present a binaural CI sound processing strategy inspired by the control of cochlear compression provided by the contralateral MOCR in natural hearing; and (2) assess the benefits of the new strategy for understanding speech presented in competition with steady noise with a speech-like spectrum in various spatial configurations of the speech and noise sources. Design: Pairs of CI sound processors (one per ear) were constructed to mimic or not mimic the effects of the contralateral MOCR on compression. For the nonmimicking condition (standard strategy or STD), the two processors in a pair functioned similarly to standard clinical processors (i.e., with fixed back-end compression and independently of each other). When configured to mimic the effects of the MOCR (MOC strategy), the two processors communicated with each other and the amount of backend compression in a given frequency channel of each processor in the pair decreased/increased dynamically (so that output levels dropped/ increased) with increases/decreases in the output energy from the corresponding frequency channel in the contralateral processor. Speech reception thresholds in speech-shaped noise were measured for 3 bilateral CI users and 2 single-sided deaf unilateral CI users. Thresholds were compared for the STD and MOC strategies in unilateral and bilateral listening conditions and for three spatial configurations of the speech and noise sources in simulated free-field conditions: speech and noise sources colocated in front of the listener, speech on the left ear with noise in front of the listener, and speech on the left ear with noise on the right ear. In both bilateral and unilateral listening, the electrical stimulus delivered to the test ear(s) was always calculated as if the listeners were wearing bilateral processors. Results: In both unilateral and bilateral listening conditions, mean speech reception thresholds were comparable with the two strategies for colocated speech and noise sources, but were at least 2 dB lower (better) with the MOC than with the STD strategy for spatially separated speech and noise sources. In unilateral listening conditions, mean thresholds improved with increasing the spatial separation between the speech and noise sources regardless of the strategy but the improvement was significantly greater with the MOC strategy. In bilateral listening conditions, thresholds improved significantly with increasing the speech-noise spatial separation only with the MOC strategy. Conclusions: The MOC strategy (1) significantly improved the intelligibility of speech presented in competition with a spatially separated noise source, both in unilateral and bilateral listening conditions; (2) produced significant spatial release from masking in bilateral listening conditions, something that did not occur with fixed compression; and (3) enhanced spatial release from masking in unilateral listening conditions. The MOC strategy as implemented here, or a modified version of it, may be usefully applied in CIs and in hearing aids

Living on the edge: contrasted wood-formation dynamics in Fagus sylvatica and Pinus sylvestris under Mediterranean conditions

Wood formation in European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) was intra-annually monitored to examine plastic responses of the xylem phenology according to altitude in one of the southernmost areas of their distribution range, i.e., in the Moncayo Natural Park, Spain. The monitoring was done from 2011 to 2013 at 1180 and 1580 m a.s.l., corresponding to the lower and upper limits of European beech forest in this region. Microcores containing phloem, cambium and xylem were collected biweekly from twenty-four trees from the beginning of March to the end of November to assess the different phases of wood formation. The samples were prepared for light microscopy to observe the following phenological phases: onset and end of cell production, onset and end of secondary wall formation in xylem cells and onset of cell maturation. The temporal dynamics of wood formation widely differed among years, altitudes and tree species. For Fagus sylvatica, the onset of cambial activity varied between the first week of May and the third week of June. Cambial activity then slowed down and stopped in summer, resulting in a length of growing season of 48–75 days. In contrast, the growing season for P. sylvestris started earlier and cambium remained active in autumn, leading to a period of activity varying from 139-170 days. The intra-annual wood-formation pattern is site and species-specific. Comparison with other studies shows a clear latitudinal trend in the duration of wood formation, positive for Fagus sylvatica and negative for P. sylvestris.Publishe

Asignación de docentes a establecimientos educativos: un enfoque multi-objetivo

Contar con una adecuada planificación logística contribuye a mejorar el funcionamiento del sistema educativo, impactando positivamente las condiciones asociadas al aprendizaje. Este trabajo propone una nueva formulación matemática del problema de Asignación de Docentes a Establecimientos Educativos (ADEE), con un enfoque multi-objetivo para: (1) minimizar la distancia entre la residencia del docente y el establecimiento educativo, (2) maximizar la cantidad de docentes asignados al mismo establecimiento educativo y (3) maximizar la cantidad de clases dictadas por un docente en diferentes turnos. Para resolver la formulación propuesta se presenta un Algoritmo Evolutivo Multi-Objetivo (MOEA) basado en el NSGA-II. Resultados experimentales con datos reales del Departamento de Alto Paraná del Ministerio de Educación y Ciencias (MEC) de Paraguay con 457 establecimientos educativos, 2995 clases y 1808 docentes, indican mejoras significativas en la asignación.XXI Workshop Tecnología Informática aplicada en Educación (WTIAE)Red de Universidades con Carreras en Informátic

Análisis de los factores de decaimiento en una repoblación de Pinus halepensis en el Sistema Ibérico zaragozano

Publishe

Asignación de estudiantes a establecimientos educativos: un enfoque multi-objetivo

En este trabajo se aborda el problema de Asignación de Estudiantes a Establecimientos Educativos (AEEE). Dicha problemática afecta la logística del sistema educativo, ya que se ve influenciada por variantes como: disponibilidad, distancia, infraestructura, entre otros. Se propone una nueva formulación matemática al problema de AEEE con un enfoque multi-objetivo para: (1) minimizar la diferencia entre la cantidad de estudiantes asignados y la cantidad óptima de estudiantes por clase, (2) minimizar la distancia promedio entre la vivienda del estudiante y el establecimiento y (3) maximizar la utilización de establecimientos con mejor infraestructura. Para resolver la formulación propuesta se plantea un Algoritmo Evolutivo Multi-Objetivo (MOEA) basado en el NSGA-II. Para la validación de esta propuesta se consideraron los datos provistos por el Ministerio de Educación y Ciencias del Paraguay (MEC) correspondientes a Ciudad del Este - Alto Paraná, del primer al tercer grado, de 90 establecimientos y 15.763 estudiantes, los resultados arrojan mejoras significativas en la cantidad de alumnos asignados por clases.XXI Workshop Tecnología Informática aplicada en Educación (WTIAE)Red de Universidades con Carreras en Informátic

Infección por VIH asociado a linfoma y herpes zóster: Reporte de caso

La infección por VIH se caracteriza por tres fases: aguda, asintomática y avanzada; esta última caracterizada por inmunodeficiencia severa, lo que expone al paciente a contraer infecciones oportunistas o cáncer. Presentamos un paciente varón de 52 años que acude por dolor en la región retromandibular izquierda, con multiples ampollas de color rojizo, aspecto descamativo, a predominio de dermatomas cervicales C4 - C5 y lumbares L1 - L5, se le realiza examen anatomopatológico del ganglio cervical encontrando hallazgos sugestivos de neoplasia linfoide maligna. Los linfomas no Hodgkin (LNH) surgen de los linfocitos B, linfocitos T y linfocitos NK. Estas neoplasias se desarrollan en los ganglios linfáticos, pero puede ocurrir en cualquier tejido. Los LNH afectan frecuentemente la cabeza y el cuello. La inmunosupresión generada por el VIH produce la reactivación del virus de varicela-zóster y es una condición de susceptibilidad para el desarrollo de linfomas.   Palabras clave: VIH (DeCS), Herpes Zóster (DeCS), Linfoma (DeCS)   DOI: http://dx.doi.org/10.17268/rmt.2021.v16i03.1

A wearable low-power and low-cost electromyographic sensor for arm prosthesis

Abstract— This work presents the design considerations for an electromyographic (EMG) sensor destined to be integrated in a low-cost robotic arm prosthetic for below-elbow amputation, which is being developed in Paraguay by a multidisciplinary teamwork. The design exposed on this paper is addressed to optimize the embedded 14 bits ADC of the MSP432P401R microcontroller. It achieves the amplification and filtering of EMG signals with an input-referred noise of 1.35 μVRMS, and a CMRR greater than 95 dB, with a very low quiescent current consumption of 40 μA. The sensor also includes a common-mode feedback circuit that drives a reference electrode.Este trabajo presenta las consideraciones de diseño para un sensor de señales de electromíograma (EMG), diseñado para ser integrado en una prótesis robótica de bajo costo, para amputaciones bajo codo, que está siendo desarrollada en Paraguay por un equipo de trabajo multidisciplinario. El diseño presentado está dirigido a optimizar el rango dinámico del ADC embebido en el microcontrolador MSP432P401R de Texas Instruments. El sensor efectúa la amplificación y el filtrado de las señales de EMG con un ruido referido a la entrada de 1.35 μVRMS, un CMRR mayor a 95 dB y un muy bajo consumo de corriente, menor a 40 μA. Este también incluye un circuito de realimentación de modo común.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Leaf morphological and physiological adaptations of a deciduous oak (Quercus faginea Lam.) to the Mediterranean climate: A comparison with a closely related temperate species (Quercus robur L.)

'White oaks' - one of the main groups of the genus Quercus L. - are represented in western Eurasia by the 'roburoid oaks', a deciduous and closely related genetic group that should have an Arcto-Tertiary origin under temperate-nemoral climates. Nowadays, roburoid oak species such as Quercus robur L. are still present in these temperate climates in Europe, but others are also present in southern Europe under Mediterranean-type climates, such as Quercus faginea Lam. We hypothesize the existence of a coordinated functional response at the whole-shoot scale in Q. faginea under Mediterranean conditions to adapt to more xeric habitats. The results reveal a clear morphological and physiological segregation between Q. robur and Q. faginea, which constitute two very contrasting functional types in response to climate dryness. The most outstanding divergence between the two species is the reduction in transpiring area in Q. faginea, which is the main trait imposed by the water deficit in Mediterranean-type climates. The reduction in leaf area ratio in Q. faginea should have a negative effect on carbon gain that is partially counteracted by a higher inherent photosynthetic ability of Q. faginea when compared with Q. robur, as a consequence of higher mesophyll conductance, higher maximum velocity of carboxylation and much higher stomatal conductance (gs). The extremely high gs of Q. faginea counteracts the expected reduction in gs imposed by the stomatal sensitivity to vapor pressure deficit, allowing this species to diminish water losses maintaining high net CO2 assimilation values along the vegetative period under nonlimiting soil water potential values. In conclusion, the present study demonstrates that Q. faginea can be regarded as an example of adaptation of a deciduous oak to Mediterranean-type climates. © 2015 The Author 2015.Publishe