scholarly journals Orthogonality-Constrained CNMF-Based Noise Reduction with Reduced Degradation of Biological Sound

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7981
Author(s):  
Naoto Murakami ◽  
Shota Nakashima ◽  
Katsuma Fujimoto ◽  
Shoya Makihira ◽  
Seiji Nishifuji ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Reduction Method ◽  
Signal To Noise Ratio ◽  
Respiratory Sounds ◽  
Chronic Obstructive ◽  
Noisy Environments ◽  
Obstructive Pulmonary Disease ◽  
Orthogonality Constraints ◽  
Average Improvement ◽  
Slow Progression

The number of deaths due to cardiovascular and respiratory diseases is increasing annually. Cardiovascular diseases with high mortality rates, such as strokes, are frequently caused by atrial fibrillation without subjective symptoms. Chronic obstructive pulmonary disease is another condition in which early detection is difficult owing to the slow progression of the disease. Hence, a device that enables the early diagnosis of both diseases is necessary. In our previous study, a sensor for monitoring biological sounds such as vascular and respiratory sounds was developed and a noise reduction method based on semi-supervised convolutive non-negative matrix factorization (SCNMF) was proposed for the noisy environments of users. However, SCNMF attenuated part of the biological sound in addition to the noise. Therefore, this paper proposes a novel noise reduction method that achieves less distortion by imposing orthogonality constraints on the SCNMF. The effectiveness of the proposed method was verified experimentally using the biological sounds of 21 subjects. The experimental results showed an average improvement of 1.4 dB in the signal-to-noise ratio and 2.1 dB in the signal-to-distortion ratio over the conventional method. These results demonstrate the capability of the proposed approach to measure biological sounds even in noisy environments.

Long-Term Auscultation in Chronic Obstructive Pulmonary Disease: Renaissance of an Ideograph of Medical Care

Respiration ◽  
2021 ◽  
pp. 1-8
Author(s):  
Sarah Bettina Schwarz ◽  
Wolfram Windisch ◽  
Daniel Sebastian Majorski ◽  
Jens Callegari ◽  
Marilena Pläcking ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Prospective Trial ◽  
Respiratory Sounds ◽  
Chronic Obstructive ◽  
Inpatient Setting ◽  
Obstructive Pulmonary Disease ◽  
Additional Information ◽  
Copd Patients

<b><i>Background:</i></b> Electronic auscultation technology has advanced dramatically in the last few years. Therefore, long-term pulmonary auscultation could provide additional information about respiratory system by monitoring acute chronic obstructive pulmonary disease (AECOPD) exacerbations or by identifying wheezing phenotypes amongst stable COPD patients. <b><i>Objectives:</i></b> Comparison of respiratory sounds in stable versus AECOPD patients recorded with a portable respiratory sound monitor over a period of 24 h. <b><i>Methods:</i></b> This prospective trial evaluated cough and wheezing events using an auscultation monitor specially developed for this purpose with 4 integrated highly sensitive microphones, in stable and severely AECOPD patients for a period of 24 h in an inpatient setting. <b><i>Results:</i></b> Twenty stable COPD patients (12 male, 60%) and 20 severely exacerbated COPD patients (14 male, 70%) were analyzed. In AECOPD patients, long-term auscultation revealed a significantly higher number of wheezing epochs than stable COPD patients (591 [IQR: 145–1,645] vs. 152 [IQR: 90–400]; <i>p</i> = 0.021). Conversely, cough epochs did not differ between AECOPD and stable COPD patients (213 [IQR: 140–327] vs. 162 [IQR: 123–243]; <i>p</i> = 0.256). The Borg-dyspnea scale, CAT score, and total CCQ score each showed no correlation with wheezing frequency, while CAT and CCQ scores did correlate with coughing frequency. <b><i>Conclusion:</i></b> Wheezing, but not coughing, occurs more frequently in AECOPD patients than in stable COPD patients, indicating that severe wheezing is an important clinical sign of exacerbation, while coughing is not. Therefore, the patterns of wheezing and coughing, as assessed by long-term auscultation, differ in stable versus exacerbated COPD patients.

scholarly journals Noise Reduction Method of Underwater Acoustic Signals Based on CEEMDAN, Effort-To-Compress Complexity, Refined Composite Multiscale Dispersion Entropy and Wavelet Threshold Denoising

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 11 ◽  
Author(s):  
Guohui Li ◽  
Qianru Guan ◽  
Hong Yang
Keyword(s):  
Noise Reduction ◽  
Empirical Mode Decomposition ◽  
Reduction Method ◽  
Signal To Noise Ratio ◽  
Acoustic Signals ◽  
Ensemble Empirical Mode Decomposition ◽  
Underwater Acoustic ◽  
Real Signal ◽  
Mode Decomposition ◽  
Soft Threshold

Owing to the problems that imperfect decomposition process of empirical mode decomposition (EMD) denoising algorithm and poor self-adaptability, it will be extremely difficult to reduce the noise of signal. In this paper, a noise reduction method of underwater acoustic signal denoising based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), effort-to-compress complexity (ETC), refined composite multiscale dispersion entropy (RCMDE) and wavelet threshold denoising is proposed. Firstly, the original signal is decomposed into several IMFs by CEEMDAN and noise IMFs can be identified according to the ETC of IMFs. Then, calculating the RCMDE of remaining IMFs, these IMFs are divided into three kinds of IMFs by RCMDE, namely noise-dominant IMFs, real signal-dominant IMFs, real IMFs. Finally, noise IMFs are removed, wavelet soft threshold denoising is applied to noise-dominant IMFs and real signal-dominant IMFs. The denoised signal can be obtained by combining the real IMFs with the denoised IMFs after wavelet soft threshold denoising. Chaotic signals with different signal-to-noise ratio (SNR) are used for denoising experiments by comparing with EMD_MSE_WSTD and EEMD_DE_WSTD, it shows that the proposed algorithm has higher SNR and smaller root mean square error (RMSE). In order to further verify the effectiveness of the proposed method, which is applied to noise reduction of real underwater acoustic signals. The results show that the denoised underwater acoustic signals not only eliminate noise interference also restore the topological structure of the chaotic attractors more clearly, which lays a foundation for the further processing of underwater acoustic signals.

scholarly journals Paradigm changes for diagnosis: using big data for prediction

2019 ◽  
Vol 57 (3) ◽  
pp. 317-327 ◽  
Author(s):  
Josep Roca ◽  
Akos Tenyi ◽  
Isaac Cano
Keyword(s):  
Personalized Medicine ◽  
Building Blocks ◽  
Chronic Obstructive ◽  
Biomedical Knowledge ◽  
Obstructive Pulmonary Disease ◽  
Policy Makers ◽  
Life Styles ◽  
Technological Potential ◽  
Slow Progression ◽  
Health And Social Care

Abstract Due to profound changes occurring in biomedical knowledge and in health systems worldwide, an entirely new health and social care scenario is emerging. Moreover, the enormous technological potential developed over the last years is increasingly influencing life sciences and driving changes toward personalized medicine and value-based healthcare. However, the current slow progression of adoption, limiting the generation of healthcare efficiencies through technological innovation, can be realistically overcome by fostering convergence between a systems medicine approach and the principles governing Integrated Care. Implicit with this strategy is the multidisciplinary active collaboration of all stakeholders involved in the change, namely: citizens, professionals with different profiles, academia, policy makers, industry and payers. The article describes the key building blocks of an open and collaborative hub currently being developed in Catalonia (Spain) aiming at generation, deployment and evaluation of a personalized medicine program addressing highly prevalent chronic conditions that often show co-occurrence, namely: cardiovascular disorders, chronic obstructive pulmonary disease, type 2 diabetes mellitus; metabolic syndrome and associated mental disturbances (anxiety-depression and altered behavioral patterns leading to unhealthy life styles).

scholarly journals Accuracy improvement of phase estimation in electron holography using noise reduction methods

Microscopy ◽  
2020 ◽  
Vol 69 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Yoshihiro Midoh ◽  
Koji Nakamae
Keyword(s):  
Noise Reduction ◽  
Reduction Method ◽  
Signal To Noise Ratio ◽  
Wiener Filter ◽  
Phase Estimation ◽  
Electron Holography ◽  
Electron Dose ◽  
Evaluation Indexes ◽  
Reduction Methods ◽  
Fourier Transform Phase

Abstract We try to improve the limit of the phase estimation of the interference fringe at low electron dose levels in electron holography by a noise reduction method. In this paper, we focus on unsupervised approaches to apply it to electron beam-sensitive and unknown samples and describe an overview of denoising methods used widely in image processing, such as wiener filter, total variation denoising, nonlocal mean filters and wavelet thresholding. We compare the wavelet hidden Markov model (WHMM) denoising that we have studied so far with the other conventional noise reduction methods. We evaluate the denoise performance of each method using the peak signal-to-noise ratio between noise-free and the target holograms (noisy or denoised holograms) and the root mean-square error (RMSE) between the true phase of the fringe and the measured phase by the discrete Fourier transform phase estimator. We show the denoised holograms for simulation and experimental data by using each noise reduction method and then discuss evaluation indexes obtained from these denoised holograms. From experimental results, it can be seen that the WHMM denoising can reduce the RMSE of fringe phase to about 1/4.5 for noisy simulation holograms and it has stable and good performance for noise reduction of observed holograms with various image qualities.

scholarly journals Monophonic and Polyphonic Wheezing Classification Based on Constrained Low-Rank Non-Negative Matrix Factorization

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1661
Author(s):  
Juan De La Torre Cruz ◽  
Francisco Jesús Cañadas Quesada ◽  
Nicolás Ruiz Reyes ◽  
Sebastián García Galán ◽  
Julio José Carabias Orti ◽  
...  
Keyword(s):  
Matrix Factorization ◽  
State Of The Art ◽  
Point Of View ◽  
Biomedical Signal Processing ◽  
Low Rank ◽  
Respiratory Sounds ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Key Indicator ◽  
Non Negative Matrix Factorization

The appearance of wheezing sounds is widely considered by physicians as a key indicator to detect early pulmonary disorders or even the severity associated with respiratory diseases, as occurs in the case of asthma and chronic obstructive pulmonary disease. From a physician’s point of view, monophonic and polyphonic wheezing classification is still a challenging topic in biomedical signal processing since both types of wheezes are sinusoidal in nature. Unlike most of the classification algorithms in which interference caused by normal respiratory sounds is not addressed in depth, our first contribution proposes a novel Constrained Low-Rank Non-negative Matrix Factorization (CL-RNMF) approach, never applied to classification of wheezing as far as the authors’ knowledge, which incorporates several constraints (sparseness and smoothness) and a low-rank configuration to extract the wheezing spectral content, minimizing the acoustic interference from normal respiratory sounds. The second contribution automatically analyzes the harmonic structure of the energy distribution associated with the estimated wheezing spectrogram to classify the type of wheezing. Experimental results report that: (i) the proposed method outperforms the most recent and relevant state-of-the-art wheezing classification method by approximately 8% in accuracy; (ii) unlike state-of-the-art methods based on classifiers, the proposed method uses an unsupervised approach that does not require any training.

scholarly journals Wheezing Sound Separation Based on Informed Inter-Segment Non-Negative Matrix Partial Co-Factorization

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2679
Author(s):  
Juan De La Torre Cruz ◽  
Francisco Jesús Cañadas Quesada ◽  
Nicolás Ruiz Reyes ◽  
Pedro Vera Candeas ◽  
Julio José Carabias Orti
Keyword(s):  
Low Income ◽  
Detection System ◽  
Early Stage ◽  
Signal To Noise Ratio ◽  
Signal Reconstruction ◽  
Respiratory Sounds ◽  
Chronic Obstructive ◽  
Respiratory Disorder ◽  
Middle Income ◽  
Sound Separation

Wheezing reveals important cues that can be useful in alerting about respiratory disorders, such as Chronic Obstructive Pulmonary Disease. Early detection of wheezing through auscultation will allow the physician to be aware of the existence of the respiratory disorder in its early stage, thus minimizing the damage the disorder can cause to the subject, especially in low-income and middle-income countries. The proposed method presents an extended version of Non-negative Matrix Partial Co-Factorization (NMPCF) that eliminates most of the acoustic interference caused by normal respiratory sounds while preserving the wheezing content needed by the physician to make a reliable diagnosis of the subject’s airway status. This extension, called Informed Inter-Segment NMPCF (IIS-NMPCF), attempts to overcome the drawback of the conventional NMPCF that treats all segments of the spectrogram equally, adding greater importance for signal reconstruction of repetitive sound events to those segments where wheezing sounds have not been detected. Specifically, IIS-NMPCF is based on a bases sharing process in which inter-segment information, informed by a wheezing detection system, is incorporated into the factorization to reconstruct a more accurate modelling of normal respiratory sounds. Results demonstrate the significant improvement obtained in the wheezing sound quality by IIS-NMPCF compared to the conventional NMPCF for all the Signal-to-Noise Ratio (SNR) scenarios evaluated, specifically, an SDR, SIR and SAR improvement equals 5.8 dB, 4.9 dB and 7.5 dB evaluating a noisy scenario with SNR = −5 dB.

scholarly journals Paths to improve diagnostic approach in chronic obstructive pulmonary disease with occupational etiology

2008 ◽  
pp. 62-66
Author(s):  
N. A. Mokina ◽  
V. A. Ageeva ◽  
P. A. Kapishnikov
Keyword(s):  
Diagnostic Methods ◽  
Respiratory Sounds ◽  
Chronic Obstructive ◽  
Occupational Hazards ◽  
Body Plethysmography ◽  
Obstructive Pulmonary Disease ◽  
Silica Dust ◽  
Lung Emphysema ◽  
Diagnostic Characteristics ◽  
History Of

The aim of this work was to study functional and diagnostic characteristics of COPD caused by exposure of occupational hazards (chronic dust related bronchitis) using conventional and novel diagnostic methods. The study involved 52 patients (28 males, 24 females) having a history of long-term exposure to low to moderate concentrations of silica dust at the workplace. Of them, 31 % were smokers, 11 % were ex-smokers quitting the smoking ≥ 1 year before, 58 % never smoked. All were diagnosed with moderate COPD. We analyzed findings of spirometry, body plethysmography, and amplitude-frequency characteristics of respiratory sounds using bronchophonography. The functional "image" of COPD caused by occupational hazards included mixed obstructive and restrictive disorders, lung emphysema signs in body plethysmography, significant obstructive disorders in bronchophonography in all the patients, bilateral diffuse and focal abnormalities of lung perfusion in multi-projectional perfusion scintigraphy, worse spirometric values in smokers compared with non-smokers.

Oral and Oropharyngeal Sensory Function in Adults With Chronic Obstructive Pulmonary Disease

2020 ◽  
Vol 29 (2) ◽  
pp. 864-872
Author(s):  
Fernanda Borowsky da Rosa ◽  
Adriane Schmidt Pasqualoto ◽  
Catriona M. Steele ◽  
Renata Mancopes
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Oral Cavity ◽  
Pulmonary Disease ◽  
Thermal Sensation ◽  
Sensory Function ◽  
Control Group ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Age Related ◽  
Copd Patients

Introduction The oral cavity and pharynx have a rich sensory system composed of specialized receptors. The integrity of oropharyngeal sensation is thought to be fundamental for safe and efficient swallowing. Chronic obstructive pulmonary disease (COPD) patients are at risk for oropharyngeal sensory impairment due to frequent use of inhaled medications and comorbidities including gastroesophageal reflux disease. Objective This study aimed to describe and compare oral and oropharyngeal sensory function measured using noninstrumental clinical methods in adults with COPD and healthy controls. Method Participants included 27 adults (18 men, nine women) with a diagnosis of COPD and a mean age of 66.56 years ( SD = 8.68). The control group comprised 11 healthy adults (five men, six women) with a mean age of 60.09 years ( SD = 11.57). Spirometry measures confirmed reduced functional expiratory volumes (% predicted) in the COPD patients compared to the control participants. All participants completed a case history interview and underwent clinical evaluation of oral and oropharyngeal sensation by a speech-language pathologist. The sensory evaluation explored the detection of tactile and temperature stimuli delivered by cotton swab to six locations in the oral cavity and two in the oropharynx as well as identification of the taste of stimuli administered in 5-ml boluses to the mouth. Analyses explored the frequencies of accurate responses regarding stimulus location, temperature and taste between groups, and between age groups (“≤ 65 years” and “> 65 years”) within the COPD cohort. Results We found significantly higher frequencies of reported use of inhaled medications ( p < .001) and xerostomia ( p = .003) in the COPD cohort. Oral cavity thermal sensation ( p = .009) was reduced in the COPD participants, and a significant age-related decline in gustatory sensation was found in the COPD group ( p = .018). Conclusion This study found that most of the measures of oral and oropharyngeal sensation remained intact in the COPD group. Oral thermal sensation was impaired in individuals with COPD, and reduced gustatory sensation was observed in the older COPD participants. Possible links between these results and the use of inhaled medication by individuals with COPD are discussed.

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