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2022 ◽  
Author(s):  
Malinda J McPherson ◽  
Josh H McDermott

Information in speech and music is often conveyed through changes in fundamental frequency (f0), the perceptual correlate of which is known as "pitch". One challenge of extracting this information is that such sounds can also vary in their spectral content due to the filtering imposed by a vocal tract or instrument body. Pitch is envisioned as invariant to spectral shape, potentially providing a solution to this challenge, but the extent and nature of this invariance remain poorly understood. We examined the extent to which human pitch judgments are invariant to spectral differences between natural sounds. Listeners performed up/down and interval discrimination tasks with spoken vowels, instrument notes, or synthetic tones, synthesized to be either harmonic or inharmonic (lacking a well-defined f0). Listeners were worse at discriminating pitch across different vowel and instrument sounds compared to when vowels/instruments were the same, being biased by differences in the spectral centroids of the sounds being compared. However, there was no interaction between this effect and that of inharmonicity. In addition, this bias decreased when sounds were separated by short delays. This finding suggests that the representation of a sound's pitch is itself unbiased, but that pitch comparisons between sounds are influenced by changes in timbre, the effect of which weakens over time. Pitch representations thus appears to be relatively invariant to spectral shape. But relative pitch judgments are not, even when spectral shape variation is naturalistic, and when such judgments are based on representations of the f0.


Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Kanghee Lee ◽  
Junho Park ◽  
Seojoo Lee ◽  
Soojeong Baek ◽  
Jagang Park ◽  
...  

Abstract A temporal boundary refers to a specific time at which the properties of an optical medium are abruptly changed. When light interacts with the temporal boundary, its spectral content can be redistributed due to the breaking of continuous time-translational symmetry of the medium where light resides. In this work, we use this principle to demonstrate, at terahertz (THz) frequencies, the resonance-enhanced spectral funneling of light coupled to a Fabry–Perot resonator with a temporal boundary mirror. To produce a temporal boundary effect, we abruptly increase the reflectance of a mirror constituting the Fabry–Perot resonator and, correspondingly, its quality factor in a step-like manner. The abrupt increase in the mirror reflectance leads to a trimming of the coupled THz pulse that causes the pulse to broaden in the spectral domain. Through this dynamic resonant process, the spectral contents of the input THz pulse are redistributed into the modal frequencies of the high-Q Fabry–Perot resonator formed after the temporal boundary. An energy conversion efficiency of up to 33% was recorded for funneling into the fundamental mode with a Fabry–Perot resonator exhibiting a sudden Q-factor change from 4.8 to 48. We anticipate that the proposed resonance-enhanced spectral funneling technique could be further utilized in the development of efficient mechanically tunable narrowband terahertz sources for diverse applications.


2022 ◽  
Author(s):  
Arie Nakhmani ◽  
Joseph Olson ◽  
Zachary Irwin ◽  
Lloyd Edwards ◽  
Christopher Gonzalez ◽  
...  

Background: Dystonia is a prevalent yet under-studied motor feature of Parkinson disease (PD). Although considerable efforts have focused on brain oscillations related to the cardinal symptoms of PD, whether dystonia is associated with specific electrophysiological features is unclear. Objectives: To investigate subcortical and cortical field potentials at rest and during contralateral hand and foot movements in PD patients with versus without dystonia. Methods: We examined the prevalence and somatotopy of dystonia in PD patients undergoing deep brain stimulation (DBS) surgery. We recorded intracranial electrophysiology from sensorimotor cortex and directional DBS electrodes in subthalamic nucleus (STN), during both rest and voluntary contralateral limb movements. We used wavelet transforms and linear mixed models to characterize spectral content in patients with and without dystonia (n=25). Results: Dystonia was highly prevalent at enrollment (61%) and most common in the foot (78%). PD patients with dystonia display greater subthalamic theta and alpha power during movement (p < 0.05) but not at rest. Regardless of dystonia status, cortical recordings display prominent beta desynchronization (13-30 Hz) during movement, whereas STN signals show increases in spectral power at lower frequencies (4-20 Hz), with peaks at 6.0 +/- 3.3 and 4.2 +/- 2.9 Hz during hand and foot movements, respectively (p < 0.03). Conclusions: Whereas cortex was characterized by beta desynchronization during hand and foot movements similarly, STN showed limb-specific low frequency activity which was increased in PD patients with dystonia. These findings may help elucidate why PD-related dystonia is most common in the foot and help guide future closed-loop DBS devices.


2022 ◽  
Vol 74 (1) ◽  
Author(s):  
Ivan Melchor ◽  
Javier Almendros ◽  
Marcia Hantusch ◽  
Sergey Samsonov ◽  
Dominique Derauw ◽  
...  

AbstractUnderstanding seismic tremor wavefields can shed light on the complex functioning of a volcanic system and, thus, improve volcano monitoring systems. Usually, several seismic stations are required to detect, characterize, and locate volcanic tremors, which can be difficult in remote areas or low-income countries. In these cases, alternative techniques have to be used. Here, we apply a data-reduction approach based on the analysis of three-component seismic data from two co-located stations operating in different times to detect and analyze long-duration tremors. We characterize the spectral content and the polarization of 355 long-duration tremors recorded by a seismic sensor located 9.5 km SE from the active vent of Copahue volcano in the period 2012–2016 and 2018–2019. We classified them as narrow- (NB) and broad-band (BB) tremors according to their spectral content. Several parameters describe the characteristic peaks composing each NB episode: polarization degree, rectilinearity, horizontal azimuth, vertical incidence. Moreover, we propose two coefficients $$C_P$$ C P and $$C_L$$ C L for describing to what extent the wavefield is polarized. For BB episodes, we extend these attributes and express them as a function of frequency. We compare the occurrence of NB and BB episodes with the volcanic activity (including the level of the crater lake, deformation, temperature, and explosive activity) to get insights into their mechanisms. This comparison suggests that the wavefield of NB tremors becomes more linearly polarized during eruptive episodes, but does not provide any specific relationship between the tremor frequency and volcanic activity. On the other hand, BB tremors show a seasonal behavior that would be related to the activity of the shallow hydrothermal system. Graphical Abstract


2022 ◽  
Author(s):  
Shayan Mookherjee

We design of compact head-end components at the transceiver level using silicon photonics to implement disaggregation for improving optical communications. We study how to use optical side channels to pass control messages without increasing the number of fibers or input/output ports. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1525090 (Year 3).


Photonics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Daniil E. Shipilo ◽  
Nikolay A. Panov ◽  
Irina A. Nikolaeva ◽  
Alexander A. Ushakov ◽  
Pavel A. Chizhov ◽  
...  

We experimentally investigate the low-frequency (below 1 THz) spectral content of broadband terahertz (THz) emission from two-color femtosecond filament formed by the 2.7-mJ, 40-fs, 800+400-nm pulse focused into air. For incoherent detection, we screened the Golay cell by the bandpass filters and measured the THz angular distributions at the selected frequencies ν=0.5, 1, 2 and 3 THz. The measured distributions of THz fluence were integrated over the forward hemisphere taking into account the transmittance of the filters, thus providing the estimation of spectral power at the frequencies studied. The spectral power decreases monotonically with the frequency increasing from 0.5 to 3 THz, thus showing that the maximum of THz spectrum is attained at ν≤0.5 THz. The THz waveform measured by electro-optical sampling (EOS) based on ZnTe crystal and transformed into the spectral domain shows that there exists the local maximum of the THz spectral power at ν≈1 THz. This disagrees with monotonic decrease of THz spectral power obtained from the filter-based measurements. We have introduced the correction to the spectral power reconstructed from EOS measurements. This correction takes into account different focal spot size for different THz frequencies contained in the broadband electromagnetic pulse. The corrected EOS spectral power is in semi-quantitative agreement with the one measured by a set of filters.


Author(s):  
Alessio Squarcini ◽  
Alexandre Solon ◽  
Gleb Oshanin

Abstract We study analytically the single-trajectory spectral density (STSD) of an active Brownian motion as exhibited, for example, by the dynamics of a chemically-active Janus colloid. We evaluate the standardly-defined spectral density, {\it i.e.} the STSD averaged over a statistical ensemble of trajectories in the limit of an infinitely long observation time $T$, and also go beyond the standard analysis by considering the coefficient of variation $\gamma$ of the distribution of the STSD. Moreover, we analyse the finite-$T$ behaviour of the STSD and $\gamma$, determine the cross-correlations between spatial components of the STSD, and address the effects of translational diffusion on the functional forms of spectral densities. The exact expressions that we obtain unveil many distinctive features of active Brownian motion compared to its passive counterpart, which allow to distinguish between these two classes based solely on the spectral content of individual trajectories.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel A. Alexander ◽  
Anthony Nomezine ◽  
Lesley A. Jarvis ◽  
David J. Gladstone ◽  
Brian W. Pogue ◽  
...  

AbstractColor vision is used throughout medicine to interpret the health and status of tissue. Ionizing radiation used in radiation therapy produces broadband white light inside tissue through the Cherenkov effect, and this light is attenuated by tissue features as it leaves the body. In this study, a novel time-gated three-channel camera was developed for the first time and was used to image color Cherenkov emission coming from patients during treatment. The spectral content was interpreted by comparison with imaging calibrated tissue phantoms. Color shades of Cherenkov emission in radiotherapy can be used to interpret tissue blood volume, oxygen saturation and major vessels within the body.


2021 ◽  
Vol 150 (4) ◽  
pp. A98-A98
Author(s):  
Nicholas Giordano ◽  
Jared W. Thacker
Keyword(s):  

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5883
Author(s):  
Mario Siciliani de Cumis ◽  
Roberto Eramo ◽  
Jie Jiang ◽  
Martin E. Fermann ◽  
Pablo Cancio Pastor

Accurate isotopic composition analysis of the greenhouse-gasses emitted in the atmosphere is an important step to mitigate global climate warnings. Optical frequency comb–based spectroscopic techniques have shown ideal performance to accomplish the simultaneous monitoring of the different isotope substituted species of such gases. The capabilities of one such technique, namely, direct comb Vernier spectroscopy, to determine the fractional isotopic ratio composition are discussed. This technique combines interferometric filtering of the comb source in a Fabry–Perot that contains the sample gas, with a high resolution dispersion spectrometer to resolve the spectral content of each interacting frequency inside of the Fabry–Perot. Following this methodology, simultaneous spectra of ro-vibrational transitions of 12C16O2 and 13C16O2 molecules are recorded and analyzed with an accurate fitting procedure. Fractional isotopic ratio 13C/12C at 3% of precision is measured for a sample of CO2 gas, showing the potentialities of the technique for all isotopic-related applications of this important pollutant.


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