arXiv subjects

Manu Francis

Publications and source records attributed to Manu Francis.

3 recordsLinked to original sources

arXiv2020

Non-uniform FIR Digital Filter Bank for Hearing Aid Application Using Frequency Response Masking Technique: A Review

Hearing aid is an electroacoustic device used to selectively amplify the audio sounds with an aim to make speech more intelligible for a hearing impaired person. Filter bank is one of the important parts of digital hearing aid where the sub band gains of each filter can be tuned to compensate an individuals unique hearing loss pattern. As the human perception is based on the logarithmic scale, nonuniform filter bank outperforms uniform filter bank. The main advantage of nonuniform filer bank is that it requires less number of sub-band filters, hence resulted in low hardware complexity and cost. Much effort has been devoted to design these nonuniform filter banks for hearing aid applications. This paper aimed to provide a review of previous researches based on nonuniform finite impulse response (FIR) digital filter bank for hearing aid application using frequency response masking (FRM) technique. By reviewing filter banks, we try to find the difference between fixed and variable band filter bank and to give an insight about which method is more suitable for matching most common types of hearing loss. Papers which involved methods of design, theoretical computation and simulation results of filter bank have been reviewed.

cs.SD↗

arXiv2020

Uncertainty Analysis in 3D SPECT Reconstruction based on Probabilistic Programming

Single Photon Emission Computed Tomography (SPECT) is one of the nuclear medicine imaging modalities used for functional analysis of animal and human organs. Gamma rays emitted from the scanned body are filtered with collimators and detected by the SPECT head that is composed of an array of gamma detectors. The conventional reconstruction algorithms do not deem the uncertainty level that is associated with the field of view of SPECT collimators. In this paper, we incorporate the probabilistic programming approach for SPECT image reconstruction. No-U-Turn Sampler (NUTS) is used to estimate the scanned object system by considering uncertainty. The obtained results indicate that the presented work in 3D SPECT image reconstruction surpassed over the conventional reconstruction methods in terms of generating uncertainty information. However, the reconstruction time needs to be improved further for phantom sizes of 128x128x128 voxels and higher.

eess.IV↗

arXiv2020

Elimination of Central Artefacts of L-SPECT with Modular Partial Ring Detectors by Shifting Center of Scanning

The Lightfield Single Photon Emission Computed Tomography (L-SPECT) system is developed to overcome some of the drawbacks in conventional SPECT by applying the idea of plenoptic imaging. This system displayed improved performance in terms of reduced information loss and scanning time when compared to the SPECT system which has a conventional collimator. The SPECT system is transformed into L-SPECT system by replacing the conventional collimators with micro-range multi-pinhole arrays. The field of view (FOV) of the L-SPECT system is enhanced by reshaping the detector head into ring-type by tiling small detector modules. The L-SPECT system with modular partial ring detectors (MPRD L-SPECT) exhibits cylindrical artefacts during volumetric reconstruction. Hence, here the work is focused to remove the cylindrical artefacts in the reconstruction of the examined objects by changing the scanning orbit. The enhancement is done such that the center of scanning of the L-SPECT system with MPRD L-SPECT is shifted at different values. The reconstruction quality of MPRD L-SPECT with and without center shifting is evaluated in terms of the Full Width at Half Maximum (FWHM) and Modulation Transfer Function (MTF). Moreover, the visual comparison is also examined. The results indicate that center shifting of MPRD L-SPECT overcomes the problem of the central artefact with improved FWHM. By increasing MPRD's scanning center shift gap, the spatial resolution can be further improved.

eess.IV↗