587 research outputs found
Vocoder-free End-to-End Voice Conversion with Transformer Network
Mel-frequency filter bank (MFB) based approaches have the advantage of
learning speech compared to raw spectrum since MFB has less feature size.
However, speech generator with MFB approaches require additional vocoder that
needs a huge amount of computation expense for training process. The additional
pre/post processing such as MFB and vocoder is not essential to convert real
human speech to others. It is possible to only use the raw spectrum along with
the phase to generate different style of voices with clear pronunciation. In
this regard, we propose a fast and effective approach to convert realistic
voices using raw spectrum in a parallel manner. Our transformer-based model
architecture which does not have any CNN or RNN layers has shown the advantage
of learning fast and solved the limitation of sequential computation of
conventional RNN. In this paper, we introduce a vocoder-free end-to-end voice
conversion method using transformer network. The presented conversion model can
also be used in speaker adaptation for speech recognition. Our approach can
convert the source voice to a target voice without using MFB and vocoder. We
can get an adapted MFB for speech recognition by multiplying the converted
magnitude with phase. We perform our voice conversion experiments on TIDIGITS
dataset using the metrics such as naturalness, similarity, and clarity with
mean opinion score, respectively.Comment: Work in progres
Adversarial Fine-tuning using Generated Respiratory Sound to Address Class Imbalance
Deep generative models have emerged as a promising approach in the medical
image domain to address data scarcity. However, their use for sequential data
like respiratory sounds is less explored. In this work, we propose a
straightforward approach to augment imbalanced respiratory sound data using an
audio diffusion model as a conditional neural vocoder. We also demonstrate a
simple yet effective adversarial fine-tuning method to align features between
the synthetic and real respiratory sound samples to improve respiratory sound
classification performance. Our experimental results on the ICBHI dataset
demonstrate that the proposed adversarial fine-tuning is effective, while only
using the conventional augmentation method shows performance degradation.
Moreover, our method outperforms the baseline by 2.24% on the ICBHI Score and
improves the accuracy of the minority classes up to 26.58%. For the
supplementary material, we provide the code at
https://github.com/kaen2891/adversarial_fine-tuning_using_generated_respiratory_sound.Comment: accepted in NeurIPS 2023 Workshop on Deep Generative Models for
Health (DGM4H
Application of the Blister Test to Assess Reliability of Polyimide Based Retinal Electrode
NBS-ERC supported by KOSEF & Korea Health 21 R&D Project(A050251)
supported by Ministry of Health & Welfar
Stethoscope-guided Supervised Contrastive Learning for Cross-domain Adaptation on Respiratory Sound Classification
Despite the remarkable advances in deep learning technology, achieving
satisfactory performance in lung sound classification remains a challenge due
to the scarcity of available data. Moreover, the respiratory sound samples are
collected from a variety of electronic stethoscopes, which could potentially
introduce biases into the trained models. When a significant distribution shift
occurs within the test dataset or in a practical scenario, it can substantially
decrease the performance. To tackle this issue, we introduce cross-domain
adaptation techniques, which transfer the knowledge from a source domain to a
distinct target domain. In particular, by considering different stethoscope
types as individual domains, we propose a novel stethoscope-guided supervised
contrastive learning approach. This method can mitigate any domain-related
disparities and thus enables the model to distinguish respiratory sounds of the
recording variation of the stethoscope. The experimental results on the ICBHI
dataset demonstrate that the proposed methods are effective in reducing the
domain dependency and achieving the ICBHI Score of 61.71%, which is a
significant improvement of 2.16% over the baseline.Comment: accepted to ICASSP 202
Electronâhole separation in ferroelectric oxides for efficient photovoltaic responses
Despite their potential to exceed the theoretical ShockleyâQueisser limit, ferroelectric photovoltaics (FPVs) have performed inefficiently due to their extremely low photocurrents. Incorporating BiâFeCrOâ(BFCO) as the light absorber in FPVs has recently led to impressively high and record photocurrents [Nechache R, et al. (2015) Nat Photonics 9:61â67], which has revived the FPV field. However, our understanding of this remarkable phenomenon is far from satisfactory. Here, we use first-principles calculations to determine that such excellent performance mainly lies in the efficient separation of electronâ hole (e-h) pairs. We show that photoexcited electrons and holes in BFCO are spatially separated on the Fe and Cr sites, respectively. This separation is much more pronounced in disordered BFCO phases, which adequately explains the observed exceptional PV responses. We further establish a design strategy to discover next-generation FPV materials. By exploring 44 additional Bi-based double-perovskite oxides, we suggest five active-layer materials that offer a combination of strong e-h separations and visible-light absorptions for FPV applications. Our work indicates that charge separation is the most important issue to be addressed for FPVs to compete with conventional devices. Keywords: ferroelectrics; double perovskites; photovoltaics; e-h separation; density functional theor
Chiral magnetoresistance in Pt/Co/Pt zigzag wires
The Rashba effect leads to a chiral precession of the spins of moving
electrons while the Dzyaloshinskii-Moriya interaction (DMI) generates
preference towards a chiral profile of local spins. We predict that the
exchange interaction between these two spin systems results in a 'chiral'
magnetoresistance depending on the chirality of the local spin texture. We
observe this magnetoresistance by measuring the domain wall (DW) resistance in
a uniquely designed Pt/Co/Pt zigzag wire, and by changing the chirality of the
DW with applying an in-plane magnetic field. A chirality-dependent DW
resistance is found, and a quantitative analysis shows a good agreement with a
theory based on the Rashba model. Moreover, the DW resistance measurement
allows us to independently determine the strength of the Rashba effect and the
DMI simultaneously, and the result implies a possible correlation between the
Rashba effect, the DMI, and the symmetric Heisenberg exchange
Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film
Transition metal oxide thin films show versatile electrical, magnetic, and
thermal properties which can be tailored by deliberately introducing
macroscopic grain boundaries via polycrystalline solids. In this study, we
focus on the modification of the magnetic and thermal transport properties by
fabricating single- and polycrystalline epitaxial SrRuO3 thin films using
pulsed laser epitaxy. Using epitaxial stabilization technique with atomically
flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin
film with crystalline quality of each grain comparable to that of
single-crystalline counterpart is realized. In particular, alleviated
compressive strain near the grain boundaries due to coalescence is evidenced
structurally, which induced enhancement of ferromagnetic ordering of the
polycrystalline epitaxial thin film. The structural variations associated with
the grain boundaries further reduce the thermal conductivity without
deteriorating the electronic transport, and lead to enhanced thermoelectric
efficiency in the epitaxial polycrystalline thin films, compared with their
single-crystalline counterpart.Comment: 24 pages, 5 figure
Electrically Evoked Cortical Potentials (EECP) in Rabbits Using Implantable Retinal Stimulation System
NBS-ERC Supported by KOSEF (Grant R11-2000-075-01001-0) & Korea
Health 21 R&D Project MOHW A05025
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