Read by QxMD icon Read

Beamforming noise

Giulia Matrone, Alessandro Ramalli, Alessandro Savoia, Piero Tortoli, Giovanni Magenes
Multi-Line Transmission (MLT) was recently demonstrated as a valuable tool to increase the frame rate of ultrasound images. In this approach, the multiple beams that are simultaneously transmitted may determine cross-talk artifacts that are typically reduced, although not eliminated, by the use of Tukey apodization on both transmission and reception apertures, which unfortunately worsens the image lateral resolution. In this paper we investigate the combination, and related performance, of Filtered-Delay Multiply And Sum (F-DMAS) beamforming with MLT for high frame-rate ultrasound imaging...
October 4, 2016: IEEE Transactions on Medical Imaging
Andrew D Brown, Francisco A Rodriguez, Cory D F Portnuff, Matthew J Goupell, Daniel J Tollin
In patients with bilateral hearing loss, the use of two hearing aids (HAs) offers the potential to restore the benefits of binaural hearing, including sound source localization and segregation. However, existing evidence suggests that bilateral HA users' access to binaural information, namely interaural time and level differences (ITDs and ILDs), can be compromised by device processing. Our objective was to characterize the nature and magnitude of binaural distortions caused by modern digital behind-the-ear HAs using a variety of stimuli and HA program settings...
October 3, 2016: Trends in Hearing
Jungmin Yoon, Kyoung Won Nam, Jun Chang Lee, Dong Pyo Jang, In Young Kim
For hearing-impaired individuals with neurological motor deficits or finger/arm amputation due to accident or disease, hearing aid adjustment using a conventional finger manipulation-based remote controller is unavailable, and a more dedicated, hands-free alternative is required. In this study, we propose an eye-blinking-based beamforming control scheme for hearing aid users. Three electroencephalogram signals measured around the ears were utilized to detect eye-blinking patterns based on a three-layer artificial neural network...
September 21, 2016: Artificial Organs
Elahe Moghimirad, Carlos A Villagomez-Hoyos, Ali Mahloojifar, Babak Mohammadzadeh Asl, Jorgen Jensen
An efficient Fourier beamformation algorithm is presented for multistatic synthetic aperture ultrasound imaging using virtual sources (FBV). The concept is based on the frequency domain wavenumber algorithm from radar and sonar and is extended to a multi-element transmit/receive configuration using virtual sources. Window functions are used to extract the azimuth processing bandwidths and weight the data to reduce sidelobes in the final image. Field II simulated data and SARUS measured data are used to evaluate the results in terms of point spread function, resolution, contrast, SNR, and processing time...
September 7, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Nghia Q Nguyen, Richard W Prager, Michael F Insana
A task-based approach is employed to develop an analytical framework for ultrasound beamformer design and evaluation. In this approach, a Bayesian ideal-observer provides an idealized starting point and a way to measure information loss in practical beamformer designs. Different approximations of this ideal strategy are shown to lead to popular beamformers in the literature, including the matched filter, minimum variance (MV), and Wiener filter (WF) beamformers. Analysis of the approximations indicates that the WF beamformer should outperform the MV approach, especially in low echo signal-to-noise conditions...
August 2016: Journal of the Acoustical Society of America
Yuxiang Hu, Haoran Zhou, Jing Lu, Xiaojun Qiu
Beamformers enable a microphone array to capture acoustic signals from a sound source with high signal to noise ratio in a noisy environment, and the linear microphone array is of particular importance, in practice, due to its simplicity and easy implementation. A linear microphone array sometimes is used near some scattering objects, which affect its beamforming performance. This paper develops a numerical model with a linear microphone array near a rigid sphere for both far-field plane wave and near-field sources...
August 2016: Journal of the Acoustical Society of America
Che-Chou Shen, Yong-Qi Xing, Gency Jeng
BACKGROUND: Generalized coherence factor (GCF) can be adaptively estimated from channel data to suppress sidelobe artifacts. Conventionally, Fast Fourier Transform (FFT) is utilized to calculate the full channel spectrum and suffers from high computation load. In this work, autocorrelation (AR)-based algorithm is utilized to provide the spectral parameters of channel data for GCF estimation with reduced complexity. METHODS: Autocorrelation relies on the phase difference among neighboring channel pairs to estimate the mean frequency and bandwidth of channel spectrum...
December 2016: Ultrasonics
Elena Boto, Richard Bowtell, Peter Krüger, T Mark Fromhold, Peter G Morris, Sofie S Meyer, Gareth R Barnes, Matthew J Brookes
Magnetoencephalography (MEG) is a sophisticated tool which yields rich information on the spatial, spectral and temporal signatures of human brain function. Despite unique potential, MEG is limited by a low signal-to-noise ratio (SNR) which is caused by both the inherently small magnetic fields generated by the brain, and the scalp-to-sensor distance. The latter is limited in current systems due to a requirement for pickup coils to be cryogenically cooled. Recent work suggests that optically-pumped magnetometers (OPMs) might be a viable alternative to superconducting detectors for MEG measurement...
2016: PloS One
Elke M J Devocht, A Miranda L Janssen, Josef Chalupper, Robert J Stokroos, Erwin L J George
OBJECTIVE: To evaluate monaural beamforming in bimodally aided cochlear implant (CI) users. DESIGN: The study enrolled twelve adult bimodal listeners with at least six months of CI-experience and using a contralateral hearing aid (HA) most of the daytime. Participants were uniformly fitted with the same CI speech processor and HA, giving access to an identical monaural beamformer in both ears. A within-subject repeated measures design evaluated three directional configurations [omnidirectional, asymmetric directivity (in CI alone) and symmetric directivity (in both CI and HA)] in two noise types [stationary and fluctuating]...
2016: PloS One
Sung Hoon Yoon, Kyoung Won Nam, Sunhyun Yook, Baek Hwan Cho, Dong Pyo Jang, Sung Hwa Hong, In Young Kim
Objectives: In an effort to improve hearing aid users' satisfaction, recent studies on trainable hearing aids have attempted to implement one or two environmental factors into training. However, it would be more beneficial to train the device based on the owner's personal preferences in a more expanded environmental acoustic conditions. Our study aimed at developing a trainable hearing aid algorithm that can reflect the user's individual preferences in a more extensive environmental acoustic conditions (ambient sound level, listening situation, and degree of noise suppression) and evaluated the perceptual benefit of the proposed algorithm...
August 10, 2016: Clinical and Experimental Otorhinolaryngology
Thomas Padois, Olivier Doutres, Franck Sgard, Alain Berry
Microphone array techniques are an efficient tool to detect acoustic source positions. The delay and sum beamforming is the standard method. In the time domain, the generalized cross-correlation can be used to compute the noise source map. This technique is based on the arithmetic mean of the spatial likelihood functions. In this study, the classical arithmetic mean is replaced by the more standard generalized mean. The noise source maps provide by the arithmetic, geometric and harmonic means are compared in the case of numerical and experimental data obtained in a reverberant room...
July 2016: Journal of the Acoustical Society of America
Shapira Lots Inbal, Zeev-Wolf Maor, Harpaz Yuval, Abeles Moshe
BACKGROUND: Magnetoencephalography measurements are often processed by using imaging algorithms such as beamforming. The estimated source magnitude tends to suffer from unbalanced scaling across different brain locations. Hence, when examining current estimates for source activity it is vital to rescale the estimated source magnitude, in order to obtain a uniformly scaled image. NEW METHOD: We present a generalized scale correction method (Nempty) that uses empty room MEG measurements to evaluate the noise level...
July 22, 2016: Journal of Neuroscience Methods
Sung Kwon, Moo Ho Bae, Sung Bae Park
Currently, minimum variance beamforming is actively investigated as a method that can improve the performance of an ultrasound beamformer, in terms of the lateral and contrast resolution. However, this method has the disadvantage of excessive computational complexity since the inverse spatial covariance matrix must be calculated. Some noticeable methods among various attempts to solve this problem include beam space adaptive beamforming methods and fast minimum variance beamforming method based on principal component analysis, which are similar in that the original signal in the element space is transformed to other domain using orthonormal basis matrix and the dimension of the covariance matrix is reduced by approximating the matrix only with important components of the matrix, hence making the inversion of the matrix very simple...
July 19, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Giso Grimm, Birger Kollmeier, Volker Hohmann
BACKGROUND: Field tests and guided walks in real environments show that the benefit from hearing aid (HA) signal processing in real-life situations is typically lower than the predicted benefit found in laboratory studies. This suggests that laboratory test outcome measures are poor predictors of real-life HA benefits. However, a systematic evaluation of algorithms in the field is difficult due to the lack of reproducibility and control of the test conditions. Virtual acoustic environments that simulate real-life situations may allow for a systematic and reproducible evaluation of HAs under more realistic conditions, thus providing a better estimate of real-life benefit than established laboratory tests...
July 2016: Journal of the American Academy of Audiology
Branislav Holländer, Gijs A G M Hendriks, Ritse M Mann, Hendrik H G Hansen, Chris L de Korte
The goal of this study was to assess whether it is viable to implement plane-wave imaging in the Automated Breast Volume Scanner (ABVS) to speed up the acquisition process. This would allow breath-hold examinations, thus reducing breathing artifacts without loss of imaging quality. A calibration phantom was scanned in an Automated Breast Volume Scanner-mimicking setup using both dynamic receive focusing with a fixed transmit focus and unfocused plane-wave compounding. Contrast-to-noise ratio and lateral resolution were compared using two beamforming schemes, delay-and-sum and Stolt's f-k algorithm...
October 2016: Ultrasound in Medicine & Biology
Rune Kaald
Dynamic receive beamforming on a delta-sigma modulator's low-resolution output bit-stream suffers from a severely increased noise floor, rendering the promising method infeasible. This work addresses the mechanism behind the increased noise floor. By using multirate theory and bifrequency analysis, we show that the increased noise floor is caused by aliasing/imaging of the powerful quantization noise from specific frequency regions according to the focus depth. We analyze both the conventional delay-and-sum method and the previously proposed insert zero compensation method...
June 21, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Ping Gong, Michael Kolios, Yuan Xu
Recently, we proposed a new method to improve the signal-to-noise ratio (SNR) of the pre-beamformed radiofrequency (RF) data in synthetic transmit aperture (STA) imaging: the delay-encoded synthetic transmit aperture (DESTA) imaging. In the decoding process of DE-STA, the equivalent STA data were obtained by directly inverting the coding matrix. This is usually regarded as an ill-posed problem especially under high noise levels. Pseudo inverse is usually used instead for seeking a more stable inversion process...
June 9, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Brooks D Lindsey, K Heath Martin, Xiaoning Jiang, Paul A Dayton
Intravascular ultrasound (IVUS) is one of the most commonly-used interventional imaging techniques and has seen recent innovations which attempt to characterize the risk posed by atherosclerotic plaques. One such development is the use of microbubble contrast agents to image vasa vasorum, fine vessels which supply oxygen and nutrients to the walls of coronary arteries and typically have diameters less than 200μm. The degree of vasa vasorum neovascularization within plaques is positively correlated with plaque vulnerability...
August 2016: Ultrasonics
Ting Ding, Hong Hu, Chen Bai, Shifang Guo, Miao Yang, Supin Wang, Mingxi Wan
Cavitation plays important roles in almost all high-intensity focused ultrasound (HIFU) applications. However, current two-dimensional (2D) cavitation mapping could only provide cavitation activity in one plane. This study proposed a three-dimensional (3D) ultrasound plane-by-plane active cavitation mapping (3D-UPACM) for HIFU in free field and pulsatile flow. The acquisition of channel-domain raw radio-frequency (RF) data in 3D space was performed by sequential plane-by-plane 2D ultrafast active cavitation mapping...
July 2016: Ultrasonics
Aaron M Thode, Katherine H Kim, Robert G Norman, Susanna B Blackwell, Charles R Greene
Masking from industrial noise can hamper the ability to detect marine mammal sounds near industrial operations, whenever conventional (pressure sensor) hydrophones are used for passive acoustic monitoring. Using data collected from an autonomous recorder with directional capabilities (Directional Autonomous Seafloor Acoustic Recorder), deployed 4.1 km from an arctic drilling site in 2012, the authors demonstrate how conventional beamforming on an acoustic vector sensor can be used to suppress noise arriving from a narrow sector of geographic azimuths...
April 2016: Journal of the Acoustical Society of America
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"