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Sound localization

Bradley D Winters, Shan-Xue Jin, Kenneth R Ledford, Nace L Golding
The principal neurons of the medial superior olive (MSO) encode cues for horizontal sound localization through comparisons of the relative timing of excitatory postsynaptic potentials (EPSPs). To understand how the timing and amplitude of EPSPs is maintained during propagation in the dendrites, we made dendritic and somatic whole-cell recordings from MSO principal neurons in brain slices from Mongolian gerbils. In somatic recordings, EPSP amplitudes were largely uniform following minimal stimulation of excitatory synapses at visualized locations along the dendrites...
February 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Gemma Huguet, Xiangying Meng, John Rinzel
Phasic neurons typically fire only for a fast-rising input, say at the onset of a step current, but not for steady or slow inputs, a property associated with type III excitability. Phasic neurons can show extraordinary temporal precision for phase locking and coincidence detection. Exemplars are found in the auditory brain stem where precise timing is used in sound localization. Phasicness at the cellular level arises from a dynamic, voltage-gated, negative feedback that can be recruited subthreshold, preventing the neuron from reaching spike threshold if the voltage does not rise fast enough...
2017: Frontiers in Computational Neuroscience
Jochen Kaiser, Maria Rieder, Cornelius Abel, Benjamin Peters, Christoph Bledowski
Previous magnetoencephalography (MEG) studies have revealed gamma-band activity at sensors over parietal and fronto-temporal cortex during the delay phase of auditory spatial and non-spatial match-to-sample tasks, respectively. While this activity was interpreted as reflecting the memory maintenance of sound features, we noted that task-related activation differences might have been present already prior to the onset of the sample stimulus. The present study focused on the interval between a visual cue indicating which sound feature was to be memorized (lateralization or pitch) and sample sound presentation to test for task-related activation differences preceding stimulus encoding...
February 15, 2017: Scientific Reports
Gaeun Kim, Hyun Mi Ju, Sun Hee Lee, Hee-Soon Kim, Jeong A Kwon, Young Joon Seo
OBJECTIVES: Bone-anchored hearing aids (BAHAs) have been known to partially restore some of the functions lost in subjects with single-sided deafness (SSD). Our aims in this systemic review were to analyze the present capabilities of BAHAs in the context of SSD, and to evaluate the efficacy of BAHAs in improving speech recognition in noisy conditions, sound localization, and subjective outcomes. DESIGN: A systematic search was undertaken until August 2015 by two independent reviewers, with disagreements resolved by consensus...
February 10, 2017: Otology & Neurotology
Camilla Tua, Simone Nessi, Lucia Rigamonti, Giovanni Dolci, Mario Grosso
In recent years, alternative food supply chains based on short distance production and delivery have been promoted as being more environmentally friendly than those applied by the traditional retailing system. An example is the supply of seasonal and possibly locally grown fruit and vegetables directly to customers inside a returnable crate (the so-called 'box scheme'). In addition to other claimed environmental and economic advantages, the box scheme is often listed among the packaging waste prevention measures...
February 1, 2017: Waste Management & Research
Michael Ortiz-Rios, Frederico A C Azevedo, Paweł Kuśmierek, Dávid Z Balla, Matthias H Munk, Georgios A Keliris, Nikos K Logothetis, Josef P Rauschecker
In primates, posterior auditory cortical areas are thought to be part of a dorsal auditory pathway that processes spatial information. But how posterior (and other) auditory areas represent acoustic space remains a matter of debate. Here we provide new evidence based on functional magnetic resonance imaging (fMRI) of the macaque indicating that space is predominantly represented by a distributed hemifield code rather than by a local spatial topography. Hemifield tuning in cortical and subcortical regions emerges from an opponent hemispheric pattern of activation and deactivation that depends on the availability of interaural delay cues...
February 6, 2017: Neuron
Ashok Mondal, Poulami Banerjee, Ajay Somkuwar
BACKGROUND AND OBJECTIVE: There is always heart sound (HS) signal interfering during the recording of lung sound (LS) signals. This obscures the features of LS signals and creates confusion on pathological states, if any, of the lungs. In this work, a new method is proposed for reduction of heart sound interference which is based on empirical mode decomposition (EMD) technique and prediction algorithm. METHOD: In this approach, first the mixed signal is split into several components in terms of intrinsic mode functions (IMFs)...
February 2017: Computer Methods and Programs in Biomedicine
Alaa Khadidos, Victor Sanchez, Chang-Tsun Li
Level set methods have been widely used to implement active contours for image segmentation applications due to their good boundary detection accuracy. In the context of medical image segmentation, weak edges and inhomogeneities remain important issues that may hinder the accuracy of any segmentation method based on active contours implemented using level set methods. This paper proposes a method based on active contours implemented using level set methods for segmentation of such medical images. The proposed method uses a level set evolution that is based on the minimization of an objective energy functional whose energy terms are weighted according to their relative importance in detecting boundaries...
February 8, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Bhuputra Panda, Harshad P Thakur
INTRODUCTION: One of the principal goals of any health care system is to improve health through the provision of clinical and public health services. Decentralization as a reform measure aims to improve inputs, management processes and health outcomes, and has political, administrative and financial connotations. It is argued that the robustness of a health system in achieving desirable outcomes is contingent upon the width and depth of 'decision space' at the local level. Studies have used different approaches to examine one or more facets of decentralization and its effect on health system functioning; however, lack of consensus on an acceptable framework is a critical gap in determining its quantum and quality...
October 31, 2016: BMC Health Services Research
Takahiro Noda, Tomoki Amemiya, Tomoyo I Shiramatsu, Hirokazu Takahashi
Humans can rapidly detect regular patterns (i.e., within few cycles) without any special attention to the acoustic environment. This suggests that human sensory systems are equipped with a powerful mechanism for automatically predicting forthcoming stimuli to detect regularity. It has recently been hypothesized that the neural basis of sensory predictions exists for not only what happens (predictive coding) but also when a particular stimulus occurs (predictive timing). Here, we hypothesize that the phases of neural oscillations are critical in predictive timing, and these oscillations are modulated in a band-specific manner when acoustic patterns become predictable, i...
2017: Frontiers in Neural Circuits
Francesco Cosentino, Cristiano Rossitto, Luigi Carlo Turco, Salvatore Gueli Alletti, Carmine Vascone, Lavinia Di Meglio, Giovanni Scambia, Mario Malzoni
CASE REPORT OBJECTIVE: To show the surgical management in laparoscopy of a particular localization of an extra-uterine pregnancy misunderstood until 12 week of EG complicated by hemoperitoneum and abortion. BACKGROUND: The prevalence of ectopic pregnancy among women who go to an emergency department with first trimester bleeding, pain, or both ranges from 1 to 16 percent [1]. The most common localization of ectopic pregnancy are the Fallopian tubes while abdominal pregnancy represent at least 1 percent of extra-uterine pregnancies...
February 4, 2017: Journal of Minimally Invasive Gynecology
C Carrie Liu, Devon Livingstone, Warren K Yunker
OBJECTIVES: To systematically review the literature on the audiological and/or quality of life benefits of a bone conduction hearing aid (BCHA) in children with congenital unilateral conductive or sensorineural deafness. METHODS: A systematic search was performed according to the PRISMA guidelines using the PubMed, Medline, and Embase databases. Data were collected on the following outcomes of interest: speech reception threshold, speech discrimination, sound localization, and quality of life measures...
March 2017: International Journal of Pediatric Otorhinolaryngology
Wilhelm Wimmer, Martin Kompis, Christof Stieger, Marco Caversaccio, Stefan Weder
OBJECTIVES: For medical or financial reasons, bilateral cochlear implantation is not always possible in bilaterally deafened patients. In such cases, a contralateral routing of signals (CROS) device could complement the monaural implant. The goal of our study was to compare the benefit of three different conditions: (1) unilateral cochlear implant (CI) alone, (2) unilateral CI complemented with a directional CROS microphone, and (3) bilateral CIs. DESIGN: Twelve bilateral experienced CI users were tested...
February 2, 2017: Ear and Hearing
Qian Tao, Chetwyn C H Chan, Yue-Jia Luo, Jian-Jun Li, Kin-Hung Ting, Zhong-Lin Lu, Susan Whitfield-Gabrieli, Jun Wang, Tatia M C Lee
Cross-modal learning requires the use of information from different sensory modalities. This study investigated how the prior visual experience of late blind individuals could modulate neural processes associated with learning of sound localization. Learning was realized by standardized training on sound localization processing, and experience was investigated by comparing brain activations elicited from a sound localization task in individuals with (late blind, LB) and without (early blind, EB) prior visual experience...
February 4, 2017: Brain Topography
Alessandro Principi, Mikhail I Katsnelson, Alex Levchenko
We study the thermal transport in two-dimensional systems with a nontrivial Berry curvature texture. The physical realizations are many; for the sake of definiteness, we consider undoped graphene gapped by the presence of an aligned hexagonal-boron-nitride substrate. The same phenomenology applies, i.e., to surface states of 3D topological insulators in the presence of a uniform magnetization. We find that chiral valley-polarized second-sound collective modes propagate along the edges of the system. The localization length of the edge modes has a topological origin stemming from the anomalous velocity term in the quasiparticle current...
January 20, 2017: Physical Review Letters
Xiaolei Li, Gaokun Yu, Ning Wang, Dazhi Gao, Haozhong Wang
Monochromatic sound source localization becomes difficult in enclosed space. According to the reciprocity theorem, a self-consistent method of source localization in enclosed space, referred to as the flux projection beamforming, is proposed, only using the measurement of the sound pressure and normal velocity on the closed boundary at a single frequency. Its validity is examined both by experiment and simulation.
January 2017: Journal of the Acoustical Society of America
Brian M Worthmann, H C Song, David R Dowling
Remote source localization in the shallow ocean at frequencies significantly above 1 kHz is virtually impossible for conventional array signal processing techniques due to environmental mismatch. A recently proposed technique called frequency-difference matched field processing (Δf-MFP) [Worthmann, Song, and Dowling (2015). J. Acoust. Soc. Am. 138(6), 3549-3562] overcomes imperfect environmental knowledge by shifting the signal processing to frequencies below the signal's band through the use of a quadratic product of frequency-domain signal amplitudes called the autoproduct...
January 2017: Journal of the Acoustical Society of America
H C Song, Chomgun Cho
The array invariant proposed for robust source localization in shallow water exploits the beam-time migration of broadband signals. The approach requires minimal knowledge of the environment, but involves plane wave beamforming using a short-aperture vertical array in stratified acoustic waveguides. In this paper, the array invariant approach is extended to a large-aperture vertical array that is sparse with significant variation of the sound speed across the aperture for conventional beamforming. The extension is feasible because the array invariant in shallow water utilizes surface/bottom-reflected arrivals that behave like those in ideal waveguides...
January 2017: Journal of the Acoustical Society of America
Anwar M N Malgoezar, Mirjam Snellen, Roberto Merino-Martinez, Dick G Simons, Pieter Sijtsma
Conventional beamforming with a microphone array is a well-established method for localizing and quantifying sound sources. It provides estimates for the source strengths on a predefined grid by determining the agreement between the pressures measured and those modeled for a source located at the grid point under consideration. As such, conventional beamforming can be seen as an exhaustive search for those locations that provide a maximum match between measured and modeled pressures. In this contribution, the authors propose to, instead of the exhaustive search, use an efficient global optimization method to search for the source locations that maximize the agreement between model and measurement...
January 2017: Journal of the Acoustical Society of America
Srinivas Varanasi, J Stuart Bolton, Thomas Siegmund
The metamaterial under investigation here consists of a periodic arrangement of unit plates in a grid-like frame such that there is a contrast in the local areal mass between cell interior and cell wall. In the low frequency range and under normal incidence this metamaterial panel exhibits a sound transmission loss significantly larger than the transmission loss of an unstructured panel with the same homogeneous mass per unit area. However, when the incident sound field is diffuse, the relative advantage of the metamaterial barrier is reduced or eliminated...
January 2017: Journal of the Acoustical Society of America
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