The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Tomotaka Nagashima - One of the best experts on this subject based on the ideXlab platform.
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Super Spectral Resolution beyond pixel Nyquist limits on multi-channel spectrometer
Optics Express, 2016Co-Authors: Tsuyoshi Konishi, Yu Yamasaki, Tomotaka NagashimaAbstract:Enhancement of the Resolution of well-distributed multi-channel spectrometers beyond the pixel Nyquist limits while maintaining their inherent advantages such as high-speed measurement, compactness, and robustness will represent a critical step toward real-time monitoring of dynamic events. Here, we report the first super Spectral Resolution measurement beyond pixel Nyquist limits which was made possible by employing the Moire effect in a commercially available Czerny-Turner type spectroscope of 4.63nm-Spectral Resolution. The experimental results show that the Spectral Resolution can be enhanced up to 0.31 nm by a factor of more than 10 with exceeding the 50-μm pixel Nyquist limits.
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Super Spectral Resolution beyond pixel Nyquist limits on multi-channel spectrometer
Optics Express, 2016Co-Authors: Tsuyoshi Konishi, Yu Yamasaki, Tomotaka NagashimaAbstract:Enhancement of the Resolution of well-distributed multi-channel spectrometers beyond the pixel Nyquist limits while maintaining their inherent advantages such as high-speed measurement, compactness, and robustness will represent a critical step toward real-time monitoring of dynamic events. Here, we report the first super Spectral Resolution measurement beyond pixel Nyquist limits which was made possible by employing the Moiré effect in a commercially available Czerny-Turner type spectroscope of 4.63nm-Spectral Resolution. The experimental results show that the Spectral Resolution can be enhanced up to 0.31 nm by a factor of more than 10 with exceeding the 50-μm pixel Nyquist limits.
Andrew J. Oxenham - One of the best experts on this subject based on the ideXlab platform.
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Speech Perception with Spectrally Non-overlapping Maskers as Measure of Spectral Resolution in Cochlear Implant Users
Journal of the Association for Research in Otolaryngology, 2019Co-Authors: Erin R. O’neill, Heather A. Kreft, Andrew J. OxenhamAbstract:Poor Spectral Resolution contributes to the difficulties experienced by cochlear implant (CI) users when listening to speech in noise. However, correlations between measures of Spectral Resolution and speech perception in noise have not always been found to be robust. It may be that the relationship between Spectral Resolution and speech perception in noise becomes clearer in conditions where the speech and noise are not Spectrally matched, so that improved Spectral Resolution can assist in separating the speech from the masker. To test this prediction, speech intelligibility was measured with noise or tone maskers that were presented either in the same Spectral channels as the speech or in interleaved Spectral channels. Spectral Resolution was estimated via a Spectral ripple discrimination task. Results from vocoder simulations in normal-hearing listeners showed increasing differences in speech intelligibility between Spectrally overlapped and interleaved maskers as well as improved Spectral ripple discrimination with increasing Spectral Resolution. However, no clear differences were observed in CI users between performance with Spectrally interleaved and overlapped maskers, or between tone and noise maskers. The results suggest that Spectral Resolution in current CIs is too poor to take advantage of the Spectral separation produced by Spectrally interleaved speech and maskers. Overall, the Spectrally interleaved and tonal maskers produce a much larger difference in performance between normal-hearing listeners and CI users than do traditional speech-in-noise measures, and thus provide a more sensitive test of speech perception abilities for current and future implantable devices.
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Effects of Spectral Resolution on Spectral contrast effects in cochlear-implant users.
Journal of the Acoustical Society of America, 2018Co-Authors: Lei Feng, Andrew J. OxenhamAbstract:The identity of a speech sound can be affected by the long-term spectrum of a preceding stimulus. Poor Spectral Resolution of cochlear implants (CIs) may affect such context effects. Here, Spectral contrast effects on a phoneme category boundary were investigated in CI users and normal-hearing (NH) listeners. Surprisingly, larger contrast effects were observed in CI users than in NH listeners, even when Spectral Resolution in NH listeners was limited via vocoder processing. The results may reflect a different weighting of Spectral cues by CI users, based on poorer Spectral Resolution, which in turn may enhance some Spectral contrast effects.
Richard J. Saykally - One of the best experts on this subject based on the ideXlab platform.
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High-Spectral-Resolution multiplex CARS spectroscopy using chirped pulses
Biomedical optics, 2004Co-Authors: Kelly P. Knutsen, Justin C. Johnson, Abigail E. Miller, Poul B. Petersen, Richard J. SaykallyAbstract:ABSTRACT A novel technique for achieving high Spectral Resolution with a femtosecond laser system is presented. Transform-limited 800 nm, 90 femtosecond (fs) pulses pass off two gratings, stretching the pulse in time to a pulse width of several picoseconds due to an induced linear temporal chirp directly proportional to the grating separation. This chirped pulse is the degenerate pump ( p ) and probe ( p' ) pulse for the CARS experiment. When overlapped in time with the 1050 nm, 90 fs transform-limited Stokes ( S ) pulse, only a fraction of the chirped p' pulse generates the CARS signal, thereby creating a temporal slit that defines the Spectral Resolution of the technique. Spectra for liquid methanol and liquid isooctane are presented, with ~6 cm -1 Spectral Resolution achieved for isooctane. Resonance enhancement and the mechanism of achieving high Spectral Resolution are shown by adjusting the S wavelength and p delay relative to the S pulse. Keywords: Coherent Anti-Stokes Raman Scattering (CARS), chirp, multiplex
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High Spectral Resolution multiplex CARS spectroscopy using chirped pulses
Chemical Physics Letters, 2004Co-Authors: Kelly P. Knutsen, Justin C. Johnson, Abigail E. Miller, Poul B. Petersen, Richard J. SaykallyAbstract:Abstract A simple technique for achieving high Spectral Resolution coherent anti-Stokes Raman scattering (CARS) spectra with a femtosecond laser system is presented. A linearly chirped and stretched (∼10 ps) pump pulse generates CARS signal only when overlapped in time with the Stokes pulse (90 fs), creating a `temporal slit' that defines the Spectral Resolution of the technique. Multiplex CARS spectra for liquid methanol and liquid isooctane are presented, demonstrating a Spectral Resolution of better than 5 cm −1 . This new chirped (c-CARS) technique should prove useful for chemically-selective imaging applications, as it significantly reduces the non-resonant background contribution.
Erin R. O’neill - One of the best experts on this subject based on the ideXlab platform.
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Speech Perception with Spectrally Non-overlapping Maskers as Measure of Spectral Resolution in Cochlear Implant Users
Journal of the Association for Research in Otolaryngology, 2019Co-Authors: Erin R. O’neill, Heather A. Kreft, Andrew J. OxenhamAbstract:Poor Spectral Resolution contributes to the difficulties experienced by cochlear implant (CI) users when listening to speech in noise. However, correlations between measures of Spectral Resolution and speech perception in noise have not always been found to be robust. It may be that the relationship between Spectral Resolution and speech perception in noise becomes clearer in conditions where the speech and noise are not Spectrally matched, so that improved Spectral Resolution can assist in separating the speech from the masker. To test this prediction, speech intelligibility was measured with noise or tone maskers that were presented either in the same Spectral channels as the speech or in interleaved Spectral channels. Spectral Resolution was estimated via a Spectral ripple discrimination task. Results from vocoder simulations in normal-hearing listeners showed increasing differences in speech intelligibility between Spectrally overlapped and interleaved maskers as well as improved Spectral ripple discrimination with increasing Spectral Resolution. However, no clear differences were observed in CI users between performance with Spectrally interleaved and overlapped maskers, or between tone and noise maskers. The results suggest that Spectral Resolution in current CIs is too poor to take advantage of the Spectral separation produced by Spectrally interleaved speech and maskers. Overall, the Spectrally interleaved and tonal maskers produce a much larger difference in performance between normal-hearing listeners and CI users than do traditional speech-in-noise measures, and thus provide a more sensitive test of speech perception abilities for current and future implantable devices.
Tsuyoshi Konishi - One of the best experts on this subject based on the ideXlab platform.
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Super Spectral Resolution beyond pixel Nyquist limits on multi-channel spectrometer
Optics Express, 2016Co-Authors: Tsuyoshi Konishi, Yu Yamasaki, Tomotaka NagashimaAbstract:Enhancement of the Resolution of well-distributed multi-channel spectrometers beyond the pixel Nyquist limits while maintaining their inherent advantages such as high-speed measurement, compactness, and robustness will represent a critical step toward real-time monitoring of dynamic events. Here, we report the first super Spectral Resolution measurement beyond pixel Nyquist limits which was made possible by employing the Moire effect in a commercially available Czerny-Turner type spectroscope of 4.63nm-Spectral Resolution. The experimental results show that the Spectral Resolution can be enhanced up to 0.31 nm by a factor of more than 10 with exceeding the 50-μm pixel Nyquist limits.
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Super Spectral Resolution beyond pixel Nyquist limits on multi-channel spectrometer
Optics Express, 2016Co-Authors: Tsuyoshi Konishi, Yu Yamasaki, Tomotaka NagashimaAbstract:Enhancement of the Resolution of well-distributed multi-channel spectrometers beyond the pixel Nyquist limits while maintaining their inherent advantages such as high-speed measurement, compactness, and robustness will represent a critical step toward real-time monitoring of dynamic events. Here, we report the first super Spectral Resolution measurement beyond pixel Nyquist limits which was made possible by employing the Moiré effect in a commercially available Czerny-Turner type spectroscope of 4.63nm-Spectral Resolution. The experimental results show that the Spectral Resolution can be enhanced up to 0.31 nm by a factor of more than 10 with exceeding the 50-μm pixel Nyquist limits.
