Benjaminmoses8414

Capacitor microphones are widely used to transduce sound waves into electrical voltages. The converting capacitor can either be operated in baseband (audio-frequency) or passband (radio-frequency, RF). A baseband operation can use a straightforward circuit implementation while a passband operation becomes more complex. The advantage of operating the capacitor in passband is a drastically lowered sensor impedance leading to superior performance, especially at high humidity levels. In this work, a digitized RF microphone is presented. Measurements prove the microphone to exceed commercial state-of-the-art small-diaphragm capacitor microphones in signal-to-noise ratio. Additionally, as the signal is digitized before demodulation, the electrical low-frequency 1/f-noise is circumvented. Furthermore, an all-digital gain ranging approach is presented, which is especially suited for the proposed system. The approach increases the system's dynamic range by digitally adjusting and correcting the microphone's sensitivity.The impact of maskers on the receiving beam of a bottlenose dolphin, Tursiops truncatus, was investigated using the auditory evoked potential (AEP) method. The test signal was a train of tone pips with a 64 kHz carrier frequency. The stimulus produced AEPs as a sequence of waves replicating the pip rate the rate following response (RFR). Selleck Caspase inhibitor The masker was band-limited noise, with a passband of 45 to 90 kHz and a level of 105 dB re 1 μPa. Masker azimuths were at 0°, ±30°, ±60°, and ±90° relative to the head midline. The receiving beam was evaluated in terms of the RFR threshold dependence on the signal azimuth. The masked thresholds were higher than the baseline thresholds, which appeared mostly as a shift rather than a deformation in the receiving beam. The largest threshold shift appeared when the masker source was located in the most sensitive direction (zero azimuth); at lateral masker source positions, the threshold shift decreased. When the masker source was not at the head midline, the masked thresholds were higher at signal positions ipsilateral to the masker source than at positions contralateral to the masker source. The largest asymmetry was observed at the 30° masker azimuth in conjunction with the ±30° and ±120° signal azimuths; the asymmetries were 5.6 and 8.1 dB, respectively. This masking asymmetry was lower than expected from the previously found interaural intensity difference, which may be explained by the conflict between the test signal and the masker when it appeared at a binaural level of the auditory system.The autoproducts are nonlinear mathematical constructs developed from acoustic fields with non-zero bandwidth. When averaged through the field's bandwidth, the autoproducts may mimic a genuine acoustic field at frequencies that are lower or higher than the original field's bandwidth. The resulting opportunity to extend signal processing to user-selectable below- or above-band frequencies is intriguing for many signal processing algorithms. Based on prior work, the limitations of the autoproducts' mimicry of out-of-band fields are understood when the in-band acoustic field is well-represented by ray acoustics. Thus, the focus in this study is on autoproducts in acoustic shadow zones behind barriers containing only diffracted acoustic fields where a sum of ray-path contributions is not an adequate field description. Diffraction is expected to be a detriment to autoproduct techniques due to its sensitivity to frequency. Two ideal shadow-zone environments with exact analytic Helmholtz-equation solutions are considered Sommerfeld's half-plane problem, also known as knife-edge diffraction, and Mie scattering from a sphere with ka = 40, where k is the wavenumber and a is the sphere's radius. With the exception of the shadow regions, autoproducts experience only mild degradation in field-mimicry performance when compared to what the ray-based theory would predict.Synchronized-spontaneous otoacoustic emissions (SSOAEs) are slow-decaying otoacoustic emissions (OAEs) that persist up to several hundred milliseconds following presentation of a transient stimulus. If the inter-stimulus interval is sufficiently short, SSOAEs will contaminate the stimulus window of the adjacent epoch. In medial-olivocochlear reflex (MOCR) assays, SSOAE contamination can present as a change in the stimulus between quiet and noise conditions, since SSOAEs are sensitive to MOCR activation. Traditionally, a change in the stimulus between MOCR conditions implicates acoustic reflex activation by the contralateral noise; however, this interpretation is potentially confounded by SSOAEs. This study examined the utility of jittering stimulus onset to desynchronize and cancel short-latency SSOAE energy. Transient-evoked (TE) OAEs and SSOAEs were measured from 39 subjects in contralateral-quiet and -noise conditions. Clicks were presented at fixed and quasi-random intervals (by introducing up to 8 ms of jitter). For the fixed-interval condition, spectral differences in the stimulus window between quiet and noise conditions mirrored those in the SSOAE analysis window, consistent with SSOAE contamination. In contrast, spectral differences stemming from SSOAEs were attenuated and/or absent in the stimulus window for the jitter conditions. The use of jitter did not have a statistically significant effect on either TEOAE level or the estimated MOCR.Underwater sounds from human sources can have detrimental effects upon aquatic animals, including fishes. Thus, it is important to establish sound exposure criteria for fishes, setting out those levels of sound from different sources that have detrimental effects upon them, in order to support current and future protective regulations. This paper considers the gaps in information that must be resolved in order to establish reasonable sound exposure criteria for fishes. The vulnerability of fishes is affected by the characteristics of underwater sounds, which must be taken into account when evaluating effects. The effects that need to be considered include death and injuries, physiological effects, and changes in behavior. Strong emphasis in assessing the effects of sounds has been placed upon the hearing abilities of fishes. However, although hearing has to be taken into account, other actual effects also have to be considered. This paper considers the information gaps that must be filled for the development of future guidelines and criteria.