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Sound localization

Jiu-Jiu Chen, Jian-Cheng Zhang, Shao-Yong Huo
Asymmetric acoustic wave propagation is important for control and manipulation of the acoustic wave signals in various devices. However, previous approach to find optimal asymmetric acoustic transmission (AAT) is through repeatedly adjusting the geometrical parameters, thus causing time-consuming. Here we propose a study on the multi-objective optimization of the AAT, aiming to achieve the widest working frequency range (fr) and the highest transmittance peak (η) with regard to the design variables. For this purpose, the Radial Basis Function (RBF) neural work and finite element (FE) method are applied to obtain the valuable data in the procedure...
September 8, 2017: Ultrasonics
Nathan Weisz, Chrysoula Lithari
Periodic modulations of an acoustic feature, such as amplitude over a certain frequency range, leads to phase locking of neural responses to the envelope of the modulation. Using electrophysiological methods this neural activity pattern, also called the auditory steady-state response (aSSR), is visible following frequency transformation of the evoked response as a clear spectral peak at the modulation frequency. Despite several studies employing the aSSR that show, for example, strongest responses for ∼40 Hz and an overall right-hemispheric dominance, it has not been investigated so far to what extent within auditory cortex different modulation frequencies elicit aSSRs at a homogenous source or whether the localization of the aSSR is topographically organized in a systematic manner...
September 11, 2017: Hearing Research
Robert Fettiplace
Sound pressure fluctuations striking the ear are conveyed to the cochlea, where they vibrate the basilar membrane on which sit hair cells, the mechanoreceptors of the inner ear. Recordings of hair cell electrical responses have shown that they transduce sound via submicrometer deflections of their hair bundles, which are arrays of interconnected stereocilia containing the mechanoelectrical transducer (MET) channels. MET channels are activated by tension in extracellular tip links bridging adjacent stereocilia, and they can respond within microseconds to nanometer displacements of the bundle, facilitated by multiple processes of Ca2+-dependent adaptation...
September 12, 2017: Comprehensive Physiology
Xu Wang, Dongxing Mao, Yong Li
A skin cloak based on the acoustic metasurface made of graded spiral units is proposed and numerically investigated. The presented skin cloak is an acoustical layer consisting of 80 subwavelength-sized unit cells, which provide precise local phase modulation and hence resort the disturbed sound filed in such a way to hide the object to acoustic wave. Numerical simulations show that the suggested skin cloak both work well under normal and small-angled incidences. By taking the advantage of the spiral-typed metasurface, the suggested skin cloak is rather thin with thickness in the order around 1/7 of the wavelength of target frequency, moreover, the intrinsic characteristics of modest dispersion ensure the skin cloak provides remarkable acoustic invisibility in a broad frequency ranging from 2500 Hz to 3600 Hz...
September 14, 2017: Scientific Reports
Christopher J G Watson, Simon Carlile, Heather Kelly, Kapilesh Balachandar
The capacity of healthy adult listeners to accommodate to altered spectral cues to the source locations of broadband sounds has now been well documented. In recent years we have demonstrated that the degree and speed of accommodation are improved by using an integrated sensory-motor training protocol under anechoic conditions. Here we demonstrate that the learning which underpins the localization performance gains during the accommodation process using anechoic broadband training stimuli generalize to environmentally relevant scenarios...
September 14, 2017: Scientific Reports
Joshua W Chamberlin, Brian R Beckman, Correigh M Greene, Casimir A Rice, Jason E Hall
While individual growth ultimately reflects the quality and quantity of food resources, intra and interspecific interactions for these resources, as well as individual size, may have dramatic impacts on growth opportunity. Out-migrating anadromous salmonids make rapid transitions between habitat types resulting in large pulses of individuals into a given location over a short period, which may have significant impact on demand for local resources. We evaluated the spatial and temporal variation in IGF-1 concentrations (a proxy for growth rate) and the relationship between size and concentration for juvenile Chinook salmon in Puget Sound, WA, USA, as a function of the relative size and abundance of both Chinook salmon and Pacific herring, a species which commonly co-occurs with salmonids in nearshore marine habitats...
September 2017: Ecology and Evolution
Anna Dudakova, Birgit Spiess, Marut Tangwattanachuleeporn, Christoph Sasse, Dieter Buchheidt, Michael Weig, Uwe Groß, Oliver Bader
The incidence of azole resistance in Aspergillus species has increased over the past years, most importantly for Aspergillus fumigatus. This is partially attributable to the global spread of only a few resistance alleles through the environment. Secondary resistance is a significant clinical concern, as invasive aspergillosis with drug-susceptible strains is already difficult to treat, and exclusion of azole-based antifungals from prophylaxis or first-line treatment of invasive aspergillosis in high-risk patients would dramatically limit drug choices, thus increasing mortality rates for immunocompromised patients...
October 2017: Clinical Microbiology Reviews
Gilles Bioley, Justine Monnerat, Marius Lötscher, Cédric Vonarburg, Adrian Zuercher, Blaise Corthésy
Due to the increasing emergence of antibiotic-resistant strains of enteropathogenic bacteria, development of alternative treatments to fight against gut infections is a major health issue. While vaccination requires that a proper combination of antigen, adjuvant, and delivery route is defined to elicit protective immunity at mucosae, oral delivery of directly active antibody preparations, referred to as passive immunization, sounds like a valuable alternative. Along the gut, the strategy suffers, however, from the difficulty to obtain sufficient amounts of antibodies with the appropriate specificity and molecular structure for mucosal delivery...
2017: Frontiers in Immunology
M I Pérez-Camacho, J C Ruiz-Suárez
The propagation of sound waves on lipid monolayers supported on water has been previously studied during the melting transition. Since changes in volume, area, and compressibility in lipid membranes have biological relevance, the observed sound propagation is of paramount importance. However, it is unknown what would occur on a lipid bilayer, which is a more approximate model of a cell membrane. With the aim to answer this relevant question, we built an experimental setup to assemble long artificial lipid membranes...
September 12, 2017: Soft Matter
Tanja Obermajer, Iztok Grabnar, Evgen Benedik, Tina Tušar, Tatjana Robič Pikel, Nataša Fidler Mis, Bojana Bogovič Matijašić, Irena Rogelj
Sound and timely microbial gut colonization completes newborn's healthy metabolic programming and manifests in infant appropriate growth and weight development. Feces, collected at 3, 30, and 90 days after birth from 60 breastfed Slovenian newborns, was submitted to microbial DNA extraction and qPCR quantification of selected gut associated taxa. Multivariate regression analysis was applied to evaluate microbial dynamics with respect to infant demographic, environmental, clinical characteristics and first year growth data...
September 11, 2017: Scientific Reports
Emily B J Coffey, Alexander M P Chepesiuk, Sibylle C Herholz, Sylvain Baillet, Robert J Zatorre
Speech-in-noise (SIN) perception is a complex cognitive skill that affects social, vocational, and educational activities. Poor SIN ability particularly affects young and elderly populations, yet varies considerably even among healthy young adults with normal hearing. Although SIN skills are known to be influenced by top-down processes that can selectively enhance lower-level sound representations, the complementary role of feed-forward mechanisms and their relationship to musical training is poorly understood...
2017: Frontiers in Neuroscience
Björn Zierul, Brigitte Röder, Claus Tempelmann, Patrick Bruns, Toemme Noesselt
Cross-modal recalibration allows the brain to maintain coherent sensory representations of the world. Using functional magnetic resonance imaging (fMRI), the present study aimed at identifying the neural mechanisms underlying recalibration in an audiovisual ventriloquism aftereffect paradigm. Participants performed a unimodal sound localization task, before and after they were exposed to adaptation blocks, in which sounds were paired with spatially disparate visual stimuli offset by 14° to the right. Behavioral results showed a significant rightward shift in sound localization following adaptation, indicating a ventriloquism aftereffect...
September 6, 2017: NeuroImage
Stuart Carson, Nancy Shackell, Joanna Mills Flemming
Spatial erosion of stock structure through local overfishing can lead to stock collapse because fish often prefer certain locations, and fisheries tend to focus on those locations. Fishery managers are challenged to maintain the integrity of the entire stock and require scientific approaches that provide them with sound advice. Here we propose a Bayesian hierarchical spatio-temporal modelling framework for fish abundance data to estimate key parameters that define spatial stock structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape)...
2017: PloS One
Shunsuke Minusa, Hisayuki Osanai, Takashi Tateno
OBJECTIVE: Recent studies have reported that micromagnetic stimulation (μMS), which can activate neural tissue and cells via sub-millimeter inductors, may address several limitations of conventional magnetic stimulation methods. Previous studies have examined the effects of μMS on single neurons, yet little is known about how μMS can affect brain tissue including local neural networks. Here, we propose a new, readily available implantable μMS system and computationally and experimentally evaluate its validity...
September 1, 2017: IEEE Transactions on Bio-medical Engineering
Vanraj, S S Dhami, B S Pabla
Gearbox plays most essential role in the modern machinery for transmitting the required torque along with motion and contributes to wide range of applications. Any failure in gearbox components affects the productivity and efficiency of the system. Most machine breakdowns related to gears are a result of improper operating conditions and loading, hence lead to failure of the whole mechanism. Ensemble Empirical Mode Decomposition (EEMD) comprises advancement and valuable addition in Empirical Mode Decomposition (EMD) and has been widely used in fault detection of rotating machines...
August 2017: Royal Society Open Science
Ikkyu Aihara, Phillip J Bishop, Michel E B Ohmer, Hiromitsu Awano, Takeshi Mizumoto, Hiroshi G Okuno, Peter M Narins, Jean-Marc Hero
Many animals use sounds produced by conspecifics for mate identification. Female insects and anuran amphibians, for instance, use acoustic cues to localize, orient toward and approach conspecific males prior to mating. Here we present a novel technique that utilizes multiple, distributed sound-indication devices and a miniature LED backpack to visualize and record the nocturnal phonotactic approach of females of the Australian orange-eyed tree frog (Litoria chloris) both in a laboratory arena and in the animal's natural habitat...
September 5, 2017: Scientific Reports
Claudio Campus, Giulio Sandini, Maria Concetta Morrone, Monica Gori
Much evidence points to an interaction between vision and audition at early cortical sites. However, the functional role of these interactions is not yet understood. Here we show an early response of the occipital cortex to sound that it is strongly linked to the spatial localization task performed by the observer. The early occipital response to a sound, usually absent, increased by more than 10-fold when presented during a space localization task, but not during a time localization task. The response amplification was not only specific to the task, but surprisingly also to the position of the stimulus in the two hemifields...
September 5, 2017: Scientific Reports
Julien Blanco, Geneviève Michon, Stéphanie M Carrière
While the aim of Ecological Intensification is to enable the design of more sustainable and productive agricultural systems, it is not suited to dryland agroecosystems that are driven by non-equilibrium dynamics and intrinsic variability. Instead, a model based on mobility and variability management has been proposed for these agroecosystems. However, this model remains under-applied in southern Morocco where there have been few studies on the functioning of traditional agroecosystems. This paper focuses on an agroecosystem in the Moroccan Saharan fringe zone that combines agriculture and pastoralism in an acacia parkland...
August 30, 2017: Journal of Environmental Management
Areti Andreopoulou, Brian F G Katz
The inter-aural time difference (ITD) is a fundamental cue for human sound localization. Over the past decades several methods have been proposed for its estimation from measured head-related impulse response (HRIR) data. Nevertheless, inter-method variations in ITD calculation have been found to exceed the known just noticeable differences (JNDs), leading to possible perceptible artifacts in virtual binaural auditory scenes, when personalized HRIRs are being used. In the absence of an objective means for validating ITD estimations, this paper examines which methods lead to the most perceptually relevant results...
August 2017: Journal of the Acoustical Society of America
Camilo Aponte-Santamaría, Jan Brunken, Frauke Gräter
Membrane tension plays various critical roles in the cell. We here asked how fast and how far localized pulses of mechanical stress dynamically propagate through biological lipid bilayers. In both coarse-grained and all-atom molecular dynamics simulations of a Dipalmitoylphosphatidylcholine lipid bilayer, we observed nanometer-wide stress pulses, propagating very efficiently longitudinally at a velocity of approximately 1.4±0.5 nm/ps (km/s), in close agreement with the expected speed of sound from experiments...
August 30, 2017: Journal of the American Chemical Society
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