Lambertkang7933

The array invariant (χ) developed for robust source-range estimation in shallow water is based on the broadband dispersion characteristics in ideal waveguides that can be summarized by the waveguide invariant, β=cos2θ, with propagation angle θ. The standard array invariant relies on the waveguide invariant being constant, e.g., β = 1, valid for small propagation angles (θ less then 20°). In this paper, the array invariant is extended to fully incorporate the angle dependence of the waveguide invariant (β=cos2θ), referred to as adaptive array invariant and denoted by χβ=χ/β, which, in theory, provides a perfect range estimate without constraining the propagation angle. The superior performance of the adaptive array invariant is illustrated via numerical simulations in an ideal waveguide, and then demonstrated using experimental data from a ship of opportunity radiating broadband noise (200-900 Hz) and a vertical array in a shallow-water environment.Old-World leaf-nosed bats (Hipposideridae) are echolocating bats with peculiar emission-side dynamics where beamforming baffles ("noseleaves") that surround the points of ultrasound emission (nostrils) change shape while diffracting the outgoing biosonar pulses. While prior work with numerical and robotic models has suggested that these noseleaf deformations could have an impact on the output characteristics of the bat's biosonar system, testing the hypothesis that this is the case in bats remains a critical step to be taken. The work presented here has tested the hypothesis that the noseleaf dynamics in a species of hipposiderid bat (Pratt's roundleaf bat, H. pratti) leads to time-variant acoustical properties on the output side of the bats' biosonar emission system. The time-variant effects of the noseleaf motion could be detected even in the presence of other sources of variability by comparing the distribution of pulse energy over the angle at different points in time. Furthermore, a convolutional neural network was able to classify the noseleaf motion state based on microphone array recordings with 85.3% accuracy. These results hence demonstrate that these nose-emitting bats have access to a substrate for behavioral flexibility on the emission-side of their biosonar systems.The diagnosis and quantification of noise-induced hearing loss (NIHL) in a medico-legal context are usually based on the pattern of hearing loss that is typically associated with long-term exposure to steady broadband noises, such as occur in noisy factories. Evidence is reviewed showing that this pattern is not typical for hearing loss produced by intense impulsive sounds of the type that military personnel are exposed to. The audiometric characteristics of noise-exposed military personnel are reviewed. A set of audiograms from a sample of 58 hearing-impaired noise-exposed military veterans was analyzed and used to develop methods for the diagnosis and quantification of military NIHL. Three requirements are specified for diagnosing military NIHL. Quantification of any loss is done by comparison with audiometric thresholds for non-noise exposed individuals, as specified in ISO7029 [International Organization for Standardization, 2017].This paper proposes a strategy to broaden the sound absorption region of porous materials by embedding ribs. The theoretical solution and the numerical simulations of the optimization model show that the composite metastructure exhibits ultra-wide high absorption characteristics and an average sound absorption coefficient of 0.937 in the 0-10 kHz range upon its teaching-learning-based optimization. High sound pressures are present only among the embedded ribs. A significant slowing down of the sound takes place inside the metastructure. Selleck AG-120 The impedance tube test confirms the design of the broadband sound absorption region in agreement with the teaching-learning-based optimization method.A classic paradigm used to quantify the perceptual weighting of binaural spatial cues requires a listener to adjust the value of one cue, while the complementary cue is held constant. Adjustments are made until the auditory percept appears centered in the head, and the values of both cues are recorded as a trading relation (TR), most commonly in μs interaural time difference per dB interaural level difference. Interestingly, existing literature has shown that TRs differ according to the cue being adjusted. The current study investigated whether cue-specific adaptation, which might arise due to the continuous, alternating presentation of signals during adjustment tasks, could account for this poorly understood phenomenon. Three experiments measured TRs via adjustment and via lateralization of single targets in virtual reality (VR). Targets were 500 Hz pure tones preceded by silence or by adapting trains that held one of the cues constant. VR removed visual anchors and provided an intuitive response technique during lateralization. The pattern of results suggests that adaptation can account for cue-dependent TRs. In addition, VR seems to be a viable tool for psychophysical tasks.Localization of acoustic sources is a common remote sensing goal. When multiple sources are present and coherent, high-resolution localization typically becomes more challenging. The spectral estimation method with additive noise (SEMWAN) is an existing technique for high-resolution localization of incoherent monopole sources in low-signal-to-noise environments. SEMWAN utilizes a reference measurement to incoherently suppress background noise, but its performance suffers in applications involving spatially-distributed coherent sources, such as like a vibrating plate. However, by subtracting a reference measurement and using subarray averaging, SEMWAN can be extended to localization of small changes in distributed coherent sources. This revised approach, the spectral estimation method with coherent background removal (SEMCBR), permits remote acoustic localization of damage in a vibrating structure. A simple multi-source experiment using an 8-by-8 planar square microphone array with 6-cm spacing in both horizontal directions was performed to validate SEMCBR at a frequency of 5.