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Beamforming noise

Sarah K Patch, Daniel E M Hoff, Tyler B Webb, Lee G Sobotka, Tianyu Zhao
PURPOSE: Range errors constrain treatment planning by limiting choice of ion beam angles and requiring large margins. Ionoacoustic range verification requires recovering the location of an acoustic source from low frequency signals. A priori information is applied to stably overcome resolution limits of inverse acoustic source imaging in this simulation study. In particular, the accuracy and robustness of ionoacoustic range verification for lateral and oblique delivery of high-energy protons to the prostate is examined...
November 20, 2017: Medical Physics
Tobias Weissgerber, Tobias Rader, Uwe Baumann
OBJECTIVE: To measure speech reception thresholds (SRTs) in co-located (S0N0) and diffuse noise conditions (multi-source noise field, MSNF) and to assess the impact of beamforming algorithms in MSNF in cochlear implant (CI) users. STUDY DESIGN: Non-randomized, open, prospective study. SETTING: Tertiary referral cochlear implantation center. PATIENTS: Participants included 14 CI users (7 bimodal, 7 bilateral) and 14 normal hearing young adults...
December 2017: Otology & Neurotology
Yuanguo Wang, Chichao Zheng, Hu Peng, Xun Chen
Recently, short-lag spatial coherence (SLSC) imaging has been widely studied to improve image contrast and contrast-to-noise ratio (CNR) in ultrasound imaging. Nevertheless, SLSC is unable to provide a good imaging resolution. Eigenspace-based minimum variance (ESBMV) beamformer was previously devised to promote imaging resolution, while enhancing imaging contrast. However, ESBMV will cause black-spot artifact problem under a high threshold of eigenvalues. Given their complementary properties, in this study, we propose an imaging method with synthetic aperture (SA) ultrasound imaging by combining SLSC weighting (SLSCw) and ESBMV, to improve imaging quality at all depth...
October 28, 2017: Computers in Biology and Medicine
Riwal Lefort, Rémi Emmetière, Sabrina Bourmani, Gaultier Real, Angélique Drémeau
This paper deals with the loss of coherence in underwater direction-of-arrival estimation. The coherence loss, which typically arises from dynamical ocean fluctuations and unknown environmental parameters, may take the form of a multiplicative colored random noise applied to the measured acoustic signal. This specific multiplicative noise needs to be addressed with methodological developments. This paper proposes a weighting process that locally mitigates the effects of the coherence loss. More specially, a set of coherent sub-antennas is designed from the so-called Mutual Coherence Function (MCF)...
October 2017: Journal of the Acoustical Society of America
Virginia Best, Elin Roverud, Christine R Mason, Gerald Kidd
A hearing-aid strategy that combines a beamforming microphone array in the high frequencies with natural binaural signals in the low frequencies was examined. This strategy attempts to balance the benefits of beamforming (improved signal-to-noise ratio) with the benefits of binaural listening (spatial awareness and location-based segregation). The crossover frequency was varied from 200 to 1200 Hz, and performance was compared to full-spectrum binaural and beamformer conditions. Speech intelligibility in the presence of noise or competing speech was measured in listeners with and without hearing loss...
October 2017: Journal of the Acoustical Society of America
Kartik Samtani, Jobin Thomas, G Abhinav Varma, David S Sumam, S P Deepu
Beamforming is a spatial filtering technique used in hearing aids to improve target sound reception by reducing interference from other directions. In this paper we propose improvements in an existing architecture present for two omnidirectional microphone array based adaptive beamforming for hearing aid applications and implement the same on Xilinx Artix 7 FPGA using VHDL coding and Xilinx Vivado(®) 2015.2. The nulls are introduced in particular directions by combination of two fixed polar patterns. This combination can be adaptively controlled to steer the null in the direction of noise...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Xueliang Zhang, DeLiang Wang
Speech signal is usually degraded by room reverberation and additive noises in real environments. This paper focuses on separating target speech signal in reverberant conditions from binaural inputs. Binaural separation is formulated as a supervised learning problem, and we employ deep learning to map from both spatial and spectral features to a training target. With binaural inputs, we first apply a fixed beamformer and then extract several spectral features. A new spatial feature is proposed and extracted to complement the spectral features...
May 2017: IEEE/ACM Transactions on Audio, Speech, and Language Processing
Gerald Kidd
Purpose: Listeners with hearing loss, as well as many listeners with clinically normal hearing, often experience great difficulty segregating talkers in a multiple-talker sound field and selectively attending to the desired "target" talker while ignoring the speech from unwanted "masker" talkers and other sources of sound. This listening situation forms the classic "cocktail party problem" described by Cherry (1953) that has received a great deal of study over the past few decades. In this article, a new approach to improving sound source segregation and enhancing auditory selective attention is described...
October 17, 2017: Journal of Speech, Language, and Hearing Research: JSLHR
Michael F Dorman, Rene H Gifford
Purpose: The aim of this article is to summarize recent published and unpublished research from our 2 laboratories on improving speech understanding in complex listening environments by listeners fit with cochlear implants (CIs). Method: CI listeners were tested in 2 listening environments. One was a simulation of a restaurant with multiple, diffuse noise sources, and the other was a cocktail party with 2 spatially separated point sources of competing speech. At issue was the value of the following sources of information, or interventions, on speech understanding: (a) visual information, (b) adaptive beamformer microphones and remote microphones, (c) bimodal fittings, that is, a CI and contralateral low-frequency acoustic hearing, (d) hearing preservation fittings, that is, a CI with preserved low-frequency acoustic in the same ear plus low-frequency acoustic hearing in the contralateral ear, and (e) bilateral CIs...
October 17, 2017: Journal of Speech, Language, and Hearing Research: JSLHR
Pham Viet Tuan, Insoo Koo
In this paper, we consider multiuser simultaneous wireless information and power transfer (SWIPT) for cognitive radio systems where a secondary transmitter (ST) with an antenna array provides information and energy to multiple single-antenna secondary receivers (SRs) equipped with a power splitting (PS) receiving scheme when multiple primary users (PUs) exist. The main objective of the paper is to maximize weighted sum harvested energy for SRs while satisfying their minimum required signal-to-interference-plus-noise ratio (SINR), the limited transmission power at the ST, and the interference threshold of each PU...
October 6, 2017: Sensors
Ece Ozkan, Valeriy Vishnevsky, Orcun Goksel
Ultrasound (US) beamforming is the process of reconstructing an image from acquired echo traces on several transducer elements. Typical beamforming approaches, such as Delay-And-Sum, perform simple projection operations, while techniques using statistical information also exist, e.g. adaptive, phase-coherence, Delay-Multiply-And-Sum, and sparse coding approaches. Inspired by the feasibility and success of inverse problem formulations in several image reconstruction problems, such as computed tomography, we herein devise an inverse problem approach for US beamforming...
September 28, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Jorge E Quijano, Lisa M Zurk
The potential benefit of a large-aperture sonar array for high resolution target localization is often challenged by the lack of sufficient data required for adaptive beamforming. This paper introduces a Toeplitz-constrained estimator of the clairvoyant signal covariance matrix corresponding to multiple far-field targets embedded in background isotropic noise. The estimator is obtained by averaging along subdiagonals of the sample covariance matrix, followed by covariance extrapolation using the method of maximum entropy...
August 2017: Journal of the Acoustical Society of America
Jørgen Hald
Measured cross-spectral matrices (CSMs) from a microphone array will in some cases be contaminated by severe incoherent noise signals in the individual channels. A typical example is flow noise generated in the individual microphones when measuring in a wind tunnel. Assuming stationary signals and performing long-time averaging, the contamination will be concentrated on the CSM diagonal. When the CSM is used for traditional frequency-domain beamforming, diagonal removal (DR) will avoid use of the diagonal. DR is effective at suppressing the contamination effects, but it also has some side effects...
August 2017: Journal of the Acoustical Society of America
Tobias Neher, Kirsten C Wagener, Matthias Latzel
Hearing aid (HA) users can differ markedly in their benefit from directional processing (or beamforming) algorithms. The current study therefore investigated candidacy for different bilateral directional processing schemes. Groups of elderly listeners with symmetric (N = 20) or asymmetric (N = 19) hearing thresholds for frequencies below 2 kHz, a large spread in the binaural intelligibility level difference (BILD), and no difference in age, overall degree of hearing loss, or performance on a measure of selective attention took part...
July 29, 2017: Hearing Research
Michael F Dorman, Sarah Natale, Anthony Spahr, Erin Castioni
Purpose: The aim of this experiment was to compare, for patients with cochlear implants (CIs), the improvement for speech understanding in noise provided by a monaural adaptive beamformer and for two interventions that produced bilateral input (i.e., bilateral CIs and hearing preservation [HP] surgery). Method: Speech understanding scores for sentences were obtained for 10 listeners fit with a single CI. The listeners were tested with and without beamformer activated in a "cocktail party" environment with spatially separated target and maskers...
August 16, 2017: Journal of Speech, Language, and Hearing Research: JSLHR
Nicole van Klink, Frank van Rosmalen, Jukka Nenonen, Sergey Burnos, Liisa Helle, Samu Taulu, Paul Lawrence Furlong, Maeike Zijlmans, Arjan Hillebrand
High frequency oscillations (HFOs, 80-500 Hz) in invasive EEG are a biomarker for the epileptic focus. Ripples (80-250 Hz) have also been identified in non-invasive MEG, yet detection is impeded by noise, their low occurrence rates, and the workload of visual analysis. We propose a method that identifies ripples in MEG through noise reduction, beamforming and automatic detection with minimal user effort. We analysed 15 min of presurgical resting-state interictal MEG data of 25 patients with epilepsy. The MEG signal-to-noise was improved by using a cross-validation signal space separation method, and by calculating ~ 2400 beamformer-based virtual sensors in the grey matter...
2017: NeuroImage: Clinical
Mingyue Yu, Yang Li, Teng Ma, K Kirk Shung, Qifa Zhou
Intravascular ultrasound (IVUS) has been frequently used for coronary artery imaging clinically. More importantly, IVUS is the fundamental image modality for most advanced multimodality intravascular imaging techniques, since it provides a more comprehensive picture of vessel anatomy on which other imaging data can be superimposed. However, image quality in the deeper region is poor because of the downgraded lateral resolution and contrast-to-noise ratio (CNR). In this paper, we report on the application of an ultrasound beamforming method that combines virtual source synthetic aperture (VSSA) focusing and coherence factor weighting (CFW) to improve the IVUS image quality...
October 2017: IEEE Transactions on Medical Imaging
Thomas E Eggers, Yazan M Dweiri, Grant A McCallum, Dominique M Durand
OBJECTIVE: Multi-channel cuff electrodes have recently been investigated for extracting fascicular-level motor commands from mixed neural recordings. Such signals could provide volitional, intuitive control over a robotic prosthesis for amputee patients. Recent work has demonstrated success in extracting these signals in acute and chronic preparations using spatial filtering techniques. These extracted signals, however, had low signal-to-noise ratios and thus limited their utility to binary classification...
October 2017: Journal of Neural Engineering
Isabelle Mosnier, Nathalie Mathias, Jonathan Flament, Dorith Amar, Amelie Liagre-Callies, Stephanie Borel, Emmanuèle Ambert-Dahan, Olivier Sterkers, Daniele Bernardeschi
The objectives of the study were to demonstrate the audiological and subjective benefits of the adaptive UltraZoom beamforming technology available in the Naída CI Q70 sound processor, in cochlear-implanted adults upgraded from a previous generation sound processor. Thirty-four adults aged between 21 and 89 years (mean 53 ± 19) were prospectively included. Nine subjects were unilaterally implanted, 11 bilaterally and 14 were bimodal users. The mean duration of cochlear implant use was 7 years (range 5-15 years)...
June 29, 2017: European Archives of Oto-rhino-laryngology
Yuling Chen, Yang Lou, Jesse Yen
During conventional ultrasound imaging, the need for multiple transmissions for one image and the time of flight for a desired imaging depth limit the frame rate of the system. Using a single plane wave pulse during each transmission followed by parallel receive processing allows for high frame rate imaging. However, image quality is degraded because of the lack of transmit focusing. Beamforming by spatial matched filtering (SMF) is a promising method which focuses ultrasonic energy using spatial filters constructed from the transmit-receive impulse response of the system...
July 2017: Ultrasonic Imaging
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