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This article is from BioMedical Engineering OnLine , volume 12 . Abstract Background: In this paper, we developed a novel algorithm to detect the valvular split between the aortic and pulmonary components in the second heart sound which is a valuable medical information. Methods: The algorithm is based on the Reassigned smoothed pseudo Wigner–Ville distribution which is a modified time–frequency distribution of the Wigner–Ville distribution. A preprocessing amplitude recovery procedure is carried out on the analysed heart sound to improve the readability of the time–frequency representation. The simulated S2 heart sounds were generated by an overlapping frequency modulated chirp–based model at different valvular split durations. Results: Simulated and real heart sounds are processed to highlight the performance of the proposed approach. The algorithm is also validated on real heart sounds of the LGB–IRCM (Laboratoire de Génie biomédical–Institut de recherches cliniques de Montréal) cardiac valve database. The A2–P2 valvular split is accurately detected by processing the obtained RSPWVD representations for both simulated and real data.

This article is from Frontiers in Computational Neuroscience , volume 7 . Abstract Interaural time difference (ITD), or the difference in timing of a sound wave arriving at the two ears, is a fundamental cue for sound localization. A wide variety of animals have specialized neural circuits dedicated to the computation of ITDs. In the avian auditory brainstem, ITDs are encoded as the spike rates in the coincidence detector neurons of the nucleus laminaris (NL). NL neurons compare the binaural phase-locked inputs from the axons of ipsi- and contralateral nucleus magnocellularis (NM) neurons. Intracellular recordings from the barn owl's NL in vivo showed that tonal stimuli induce oscillations in the membrane potential. Since this oscillatory potential resembled the stimulus sound waveform, it was named the sound analog potential (Funabiki et al., 2011). Previous modeling studies suggested that a convergence of phase-locked spikes from NM leads to an oscillatory membrane potential in NL, but how presynaptic, synaptic, and postsynaptic factors affect the formation of the sound analog potential remains to be investigated. In the accompanying paper, we derive analytical relations between these parameters and the signal and noise components of the oscillation. In this paper, we focus on the effects of the number of presynaptic NM fibers, the mean firing rate of these fibers, their average degree of phase-locking, and the synaptic time scale. Theoretical analyses and numerical simulations show that, provided the total synaptic input is kept constant, changes in the number and spike rate of NM fibers alter the ITD-independent noise whereas the degree of phase-locking is linearly converted to the ITD-dependent signal component of the sound analog potential. The synaptic time constant affects the signal more prominently than the noise, making faster synaptic input more suitable for effective ITD computation.

The Biological Review, The City College of the College of the City of New York : v.10, no.1, March 1948

We use a publicly available numerical wave-propagation simulation of Hartlep et al. 2011 to test the ability of helioseismic holography to detect signatures of a compact, fully submerged, 5% sound-speed perturbation placed at a depth of 50 Mm within a solar model. We find that helioseismic holography as employed in a nominal "lateral-vantage" or "deep-focus" geometry employing quadrants of an annular pupil is capable of detecting and characterizing the perturbation. A number of tests of the methodology, including the use of a plane-parallel approximation, the definition of travel-time shifts, the use of different phase-speed filters, and changes to the pupils, are also performed. It is found that travel-time shifts made using Gabor-wavelet fitting are essentially identical to those derived from the phase of the Fourier transform of the cross-covariance functions. The errors in travel-time shifts caused by the plane-parallel approximation can be minimized to less than a second for the depths and fields of view considered here. Based on the measured strength of the mean travel-time signal of the perturbation, no substantial improvement in sensitivity is produced by varying the analysis procedure from the nominal methodology in conformance with expectations. The measured travel-time shifts are essentially unchanged by varying the profile of the phase-speed filter or omitting the filter entirely. The method remains maximally sensitive when applied with pupils that are wide quadrants, as opposed to narrower quadrants or with pupils composed of smaller arcs. We discuss the significance of these results for the recent controversy regarding suspected pre-emergence signatures of active regions.

In this scoping review, we will summarize the current landscape of objective cough sound assessment tools. We will examine how these tools are being used to improve outcomes among people affected by various respiratory diseases and conditions.

The objective of this research was to evaluate the effectiveness of a portable, four-loudspeaker array for assessments of helmet effects on wearer s detection and localization of sound sources. Military and civilian helmets affect the wearer s ability to detect and localize sound sources. There is industry need to evaluate auditory effects in helmet development and modification processes, but ongoing, well-controlled laboratory studies are prohibitively time-consuming and costly. A portable four-loudspeaker test array was used to compare the auditory effects of two prototype and two fielded helmets to a bare-head condition. Detection thresholds were measured for one-third-octave noise bands (125 8000 Hz). Localization performance was assessed for low-pass (500 Hz) speech sounds and high-pass (2 kHz) breaking glass sounds in the presence of two background noises. Detectability of sound sources varied both with the helmet type and the sound source type/location. Average sound attenuation across all test conditions was less than 1.5 dB for each helmet tested, but varied with frequency, reaching 7.0 dB for some helmets. Effects of helmet on sound source localization were large, significant, and varied with type of helmet.

The objective of this research was to evaluate the effectiveness of a portable, four-loudspeaker array for assessments of helmet effects on wearer s detection and localization of sound sources. Military and civilian helmets affect the wearer s ability to detect and localize sound sources. There is industry need to evaluate auditory effects in helmet development and modification processes, but ongoing, well-controlled laboratory studies are prohibitively time-consuming and costly. A portable four-loudspeaker test array was used to compare the auditory effects of two prototype and two fielded helmets to a bare-head condition. Detection thresholds were measured for one-third-octave noise bands (125 8000 Hz). Localization performance was assessed for low-pass (500 Hz) speech sounds and high-pass (2 kHz) breaking glass sounds in the presence of two background noises. Detectability of sound sources varied both with the helmet type and the sound source type/location. Average sound attenuation across all test conditions was less than 1.5 dB for each helmet tested, but varied with frequency, reaching 7.0 dB for some helmets. Effects of helmet on sound source localization were large, significant, and varied with type of helmet.

An attempt to describe the atmospheric boundary layer during the (Marginal Ice Zone Experiment) MIZEX 84 from 11 July to 17 July was made using a sodar system. The computation of the temperature structure parameter CT2 in the surface layer using in situ measurements allowed the calibration of the system. A program was developed to obtain the inversion layer height Zi, where the signal reaches a maximum. The thickness of the inversion layer was also computed and was used with the calibration law to compute CT(2) at the inversion layer. Refractive trapping conditions were evident on 15 July although the generally small value of the heat flux did not indicate a strongly unstable boundary layer. Comparison with two radiosonde profiles shows good agreement in one case. It is the purpose of this thesis to calibrate the sodar system deployed by the research vessel POLAR QUEEN during MIZEX 84 to obtain the refractive-index structure parameter. The tme-height structure of the boundary layer will also be investigated. Efforts will also be made to compute the height of the inversion layer and to estimate its thickness, the jump of potential temperature, and the refractive-index gradient.