Machine learning in acoustics: Theory and applications.

Acoustic data provide scientific and engineering insights in fields ranging from biology and communications to ocean and Earth science. We survey the recent advances and transformative potential of machine learning (ML), including deep learning, in the field of acoustics. ML is a broad family of techniques, which are often based in statistics, for automatically detecting and utilizing patterns in data. Relative to conventional acoustics and signal processing, ML is data-driven. Given sufficient training data, ML can discover complex relationships between features and desired labels or actions, or between features themselves. With large volumes of training data, ML can discover models describing complex acoustic phenomena such as human speech and reverberation. ML in acoustics is rapidly developing with compelling results and significant future promise. We first introduce ML, then highlight ML developments in four acoustics research areas: source localization in speech processing, source localization in ocean acoustics, bioacoustics, and environmental sounds in everyday scenes.

Evaluation of platelet response to different clopidogrel dosing regimens in patients with acute coronary syndrome in clinical practice.

High-post clopidogrel platelet reactivity in acute coronary syndrome (ACS) patients is associated with adverse outcomes and may be related to clopidogrel dosing. Clinical studies evaluating different clopidogrel doses have resulted in conflicting conclusions. Clopidogrel dosing regimens have evolved over time, enabling us to evaluate platelet reactivity in real-life ACS patients undergoing percutaneous coronary intervention and treated with three different clopidogrel doses. Platelet reactivity was assessed with light transmitted aggregometry on the third day post clopidogrel loading in 404 consecutive ACS patients. Of them, 198 were treated with a standard regimen (300 mg loading, 75 mg/day maintenance dose), 95 with a high loading regimen (600 mg loading, 75 mg/day maintenance dose) and 111 with a high loading/high maintenance regimen (600 mg loading, 150 mg/day maintenance). Compared with the standard regimen, the high loading regimen resulted in significantly lower mean platelet reactivity to adenosine diphosphate (ADP) with a lower proportion of patients exhibiting clopidogrel non-responsiveness (11% vs. 28%, p = 0.004). Compared with the high loading regimen, the high loading/high maintenance regimen resulted in significantly lower mean platelet reactivity to ADP, but without a further drop in the number of non-responders (8.1% vs. 11%, p = 0.16). In conclusion, greater overall inhibition can be achieved with higher loading and maintenance doses in ACS patients. However, despite high clopidogrel doses, a sizable proportion of patients remained "resistant" to the effects of clopidogrel.

Higher Syntax score is not predictive of late mortality in "real-world" patients with multivessel coronary artery disease undergoing coronary artery bypass grafting.

BACKGROUND: The Syntax score (SS) is a helpful tool for determining the optimal revascularization strategy regarding coronary artery bypass surgery (CABG) vs. percutaneous coronary intervention (PCI) in patients with complex coronary disease. While an association between higher SS and mortality was found for PCI patients, no such association was found for CABG patients. OBJECTIVES: To assess whether the SS predicts late mortality in patients undergoing CABG in a real-world setting. METHODS: The study included 406 consecutive patients referred for CABG over a 2 year period. Baseline and clinical characteristics were collected. Angiographic data SS were interpreted by an experienced angiographer. Patients were divided into three groups based on SS tertiles: low ≤ 21 (n = 205), intermediate 22-31 (n = 138), and high ≥ 32 (n = 63). Five year mortality was derived from the National Mortality Database. RESULTS: Compared with low SS, patients with intermediate and high scores were significantly older (P = 0.02), had lower left ventricular ejection fraction (64% vs. 52% and 48%, P < 0.001) and greater incidence of acute coronary syndrome, left main disease, presence of chronic total occlusion of the left anterior descending and/or right coronary artery, and a higher EuroSCORE (5% vs. 5% and 8%, P < 0.01). Patients with intermediate and high SS had higher 5 year mortality rates (18.1% and 19%, respectively) compared to patients with low score (9.8%, P = 0.04). On multivariate analysis, SS was not an independent predictor of late mortality. CONCLUSION: Patients with lower SS had lower mortality after CABG, which is attributable to lower baseline risk. SS is not independently predictive of late mortality in patients with multi-vessel coronary artery disease undergoing CABG.

Unveiling gender differences in psychophysiological dynamics: support for a two-dimensional autonomic space approach.

Introduction: To date, studies focusing on the connection between psychological functioning and autonomic nervous system (ANS) activity usually adopted the one-dimensional model of autonomic balance, according to which activation of one branch of the ANS is accompanied by an inhibition of the other. However, the sympathetic and parasympathetic branches also activate independently; thus, co-activation and co-inhibition may occur, which is demonstrated by a two-dimensional model of ANS activity. Here, we apply such models to assess how markers of the autonomic space relate to several critical psychological constructs: emotional contagion (EC), general anxiety, and positive and negative affect (PA and NA). We also examined gender differences in those psychophysiological relations. Methods: In the present study, we analyzed data from 408 healthy students, who underwent a 5-min group baseline period as part of their participation in several experiments and completed self-reported questionnaires. Electrocardiogram (ECG), electrodermal activity (EDA), and respiration were recorded. Respiratory sinus arrhythmia (RSA), pre-ejection period (PEP), as well as cardiac autonomic balance (CAB) and regulation (CAR) and cross-system autonomic balance (CSAB) and regulation (CSAR), were calculated. Results: Notably, two-dimensional models were more suitable for predicting and describing most psychological constructs. Gender differences were found in psychological and physiological aspects as well as in psychophysiological relations. Women's EC scores were negatively correlated with sympathetic activity and positively linked to parasympathetic dominance. Men's PA and NA scores were positively associated with sympathetic activity. PA in men also had a positive link to an overall activation of the ANS, and a negative link to parasympathetic dominance. Discussion: The current results expand our understanding of the psychological aspects of the autonomic space model and psychophysiological associations. Gender differences and strengths and weaknesses of alternative physiological models are discussed.

Percutaneous coronary intervention in patients with haemophilia presenting with acute coronary syndrome: an interventional dilemma: case series, review of the literature, and tips for management.

Since the introduction of clotting factor concentrates over 50 years ago the life expectancy of patients with hemophilia (PWH) has increased to over 70 years. Consequently, diseases of the ageing population, including coronary artery disease, are increasingly being encountered. These patients present a unique therapeutic problem due to their greatly increased bleeding risk. Randomized controlled studies specific to PWH are lacking, emphasizing the need for case series. We present three cases of acute coronary syndrome in PWH who underwent urgent percutaneous coronary intervention at our institution, and summarize the available literature on the topic. We describe their management and outcome and provide points to consider when treating these complex patients.

Maximum likelihood estimation of direction of arrival using an acoustic vector-sensor.

A vector-sensor consisting of a monopole sensor collocated with orthogonally oriented dipole sensors is used for direction of arrival (DOA) estimation in the presence of an isotropic noise-field or internal device noise. A maximum likelihood (ML) DOA estimator is derived and subsequently shown to be a special case of DOA estimation by means of a search for the direction of maximum steered response power (SRP). The problem of SRP maximization with respect to a vector-sensor can be solved with a computationally inexpensive algorithm. The ML estimator achieves asymptotic efficiency and thus outperforms existing estimators with respect to the mean square angular error (MSAE) measure. The beampattern associated with the ML estimator is shown to be identical to that used by the minimum power distortionless response beamformer for the purpose of signal enhancement.

Intrapersonal and interpersonal vocal affect dynamics during psychotherapy.

OBJECTIVE: The present study implements an automatic method of assessing arousal in vocal data as well as dynamic system models to explore intrapersonal and interpersonal affect dynamics within psychotherapy and to determine whether these dynamics are associated with treatment outcomes. METHOD: The data of 21,133 mean vocal arousal observations were extracted from 279 therapy sessions in a sample of 30 clients treated by 24 therapists. Before and after each session, clients self-reported their well-being level, using the Outcome Rating Scale. RESULTS: Both clients' and therapists' vocal arousal showed intrapersonal dampening. Specifically, although both therapists and clients departed from their baseline, their vocal arousal levels were "pulled" back to these baselines. In addition, both clients and therapists exhibited interpersonal dampening. Specifically, both the clients' and the therapists' levels of arousal were "pulled" toward the other party's arousal level, and clients were "pulled" by their therapists' vocal arousal toward their own baseline. These dynamics exhibited a linear change over the course of treatment: whereas interpersonal dampening decreased over time, there was an increase in intrapersonal dampening over time. In addition, higher levels of interpersonal dampening were associated with better session outcomes. CONCLUSIONS: These findings demonstrate the advantages of using automatic vocal measures to capture nuanced intrapersonal and interpersonal affect dynamics in psychotherapy and demonstrate how these dynamics are associated with treatment gains. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

On the angular error of intensity vector based direction of arrival estimation in reverberant sound fields.

An acoustic vector sensor provides measurements of both the pressure and particle velocity of a sound field in which it is placed. These measurements are vectorial in nature and can be used for the purpose of source localization. A straightforward approach towards determining the direction of arrival (DOA) utilizes the acoustic intensity vector, which is the product of pressure and particle velocity. The accuracy of an intensity vector based DOA estimator in the presence of noise has been analyzed previously. In this paper, the effects of reverberation upon the accuracy of such a DOA estimator are examined. It is shown that particular realizations of reverberation differ from an ideal isotropically diffuse field, and induce an estimation bias which is dependent upon the room impulse responses (RIRs). The limited knowledge available pertaining the RIRs is expressed statistically by employing the diffuse qualities of reverberation to extend Polack's statistical RIR model. Expressions for evaluating the typical bias magnitude as well as its probability distribution are derived.

Generating nonstationary multisensor signals under a spatial coherence constraint.

Noise fields encountered in real-life scenarios can often be approximated as spherical or cylindrical noise fields. The characteristics of the noise field can be described by a spatial coherence function. For simulation purposes, researchers in the signal processing community often require sensor signals that exhibit a specific spatial coherence function. In addition, they often require a specific type of noise such as temporally correlated noise, babble speech that comprises a mixture of mutually independent speech fragments, or factory noise. Existing algorithms are unable to generate sensor signals such as babble speech and factory noise observed in an arbitrary noise field. In this paper an efficient algorithm is developed that generates multisensor signals under a predefined spatial coherence constraint. The benefit of the developed algorithm is twofold. Firstly, there are no restrictions on the spatial coherence function. Secondly, to generate M sensor signals the algorithm requires only M mutually independent noise signals. The performance evaluation shows that the developed algorithm is able to generate a more accurate spatial coherence between the generated sensor signals compared to the so-called image method that is frequently used in the signal processing community.

Optical realization of Viterbi decoder for communication network.

The advantages of optics that include processing speed and information throughput, modularity and versatility could be incorporated into one of the most interesting and applicable topics of digital communication related to Viterbi decoders. We aim to accelerate the processing rate and capabilities of Viterbi decoders applied for convolution codes, speech recognition, inter symbol interference (ISI) mitigation problems. The suggested configuration for realizing the decoder is based upon fast optical switches. The configuration is very modular and can easily be increased to Viterbi decoder based upon state machine with larger number of states and depth of the trellis diagram.

Generating sensor signals in isotropic noise fields.

Researchers in the signal processing community often require sensor signals that result from a spherically or cylindrically isotropic noise field for simulation purposes. Although it has been shown that these signals can be generated using a number of uncorrelated noise sources that are uniformly spaced on a sphere or cylinder, this method is seldom used in practice. In this paper algorithms that generate sensor signals of an arbitrary one- and three-dimensional array that result from a spherically or cylindrically isotropic noise field are developed. Furthermore, the influence of the number of noise sources on the accuracy of the generated sensor signals is investigated.

Impact of coronary chronic total occlusions on long-term mortality in patients undergoing coronary artery bypass grafting.

OBJECTIVES: The presence of a coronary chronic total occlusion (CTO) is a common consideration in favour of surgical revascularization. However, studies have shown that not all patients undergoing coronary artery bypass grafting (CABG) have a bypass graft placed on the CTO vessel. The aim of this study was to determine the prevalence of CTO among patients referred for CABG and the significance of incomplete CTO revascularization in these patients. METHODS: The study included 405 consecutive patients undergoing CABG during a 2-year period. Clinical, echocardiographic and angiographic data were collected. Determination of whether or not a CTO was bypassed was made by correlating data from the surgical reports and preprocedural angiograms. The primary end point of this study was 5-year all-cause mortality. RESULTS: Two hundred and twenty-one CTOs were found in 174 patients: 132 patients (76) had 1 CTO; 37 (21) had 2 CTOs and 5 (3) had 3 CTOs. Of the 221 CTOs, 191 (86%) were bypassed. All left anterior descending (LAD) CTOs were grafted; however, 12 of left circumflex and 22% of right coronary artery CTOs did not receive bypass grafts. Incomplete CTO revascularization was associated with older age, more comorbidities, including stroke, renal impairment and lower ejection fraction. However, incomplete CTO revascularization was not associated with increased 5-year mortality. CONCLUSIONS: Coronary CTOs are a common finding in patients referred for bypass surgery. The presence of a CTO is not independently associated with an adverse long-term outcome. While most CTOs are successfully bypassed, failure to revascularize a non-LAD CTO is not associated with adverse long-term outcome.

Predictors and outcomes associated with radial versus femoral access for intervention in patients with acute coronary syndrome in a real-world setting: results from the Acute Coronary Syndrome Israeli Survey (ACSIS) 2010.

BACKGROUND: Use of transradial intervention (TRI) is becoming more popular, and recent studies suggest an advantage for TRI in high-risk patients presenting with acute coronary syndrome (ACS). The aim of our study was to describe current utilization and outcomes of transradial intervention (TRI) in real-world patients presenting with ACS. METHODS: Data were derived from the ACS Israeli Survey (ACSIS 2010), a nationwide prospective survey of patients presenting with ACS over a 2-month period. Follow-up was continued for up to 1 year. RESULTS: Of 1815 ACS patients undergoing coronary angiography, 613 (34%) underwent TRI, which was more likely to be employed among patients with lower-risk characteristics. Patients undergoing TRI had significantly lower 30-day mortality and in-hospital bleeding. On multivariate analysis, the risk of in-hospital major bleeding was reduced by 60% in patients undergoing TRI (P=.04). However, no significant differences in other components of major adverse cardiac events or mortality were demonstrated at 30 days. All-cause mortality at 1 year was significantly lower among patients who underwent TRI. However, after multivariate adjustment, this effect was no longer significant. CONCLUSIONS: In our study of real-world patients, better TRI outcomes are related largely to lower baseline risk of patients allocated to this approach, suggesting that TRI may be underutilized in high-risk ACS patients.

Current perspectives on coronary chronic total occlusions: the Canadian Multicenter Chronic Total Occlusions Registry.

OBJECTIVES: The purpose of this study was to determine the prevalence, clinical characteristics, and management of coronary chronic total occlusions (CTOs) in current practice. BACKGROUND: There is little evidence in contemporary literature concerning the prevalence, clinical characteristics, and treatment decisions regarding patients who have coronary CTOs identified during coronary angiography. METHODS: Consecutive patients undergoing nonurgent coronary angiography with CTO were prospectively identified at 3 Canadian sites from April 2008 to July 2009. Patients with previous coronary artery bypass graft surgery or presenting with acute ST-segment elevation myocardial infarction were excluded. Detailed baseline clinical, angiographic, electrocardiographic, and revascularization data were collected. RESULTS: Chronic total occlusions were identified in 1,697 (18.4%) patients with significant coronary artery disease (>50% stenosis in ≥1 coronary artery) who were undergoing nonemergent angiography. Previous history of myocardial infarction was documented in 40% of study patients, with electrocardiographic evidence of Q waves corresponding to the CTO artery territory in only 26% of cases. Left ventricular function was normal in >50% of patients with CTO. Half the CTOs were located in the right coronary artery. Almost half the patients with CTO were treated medically, and 25% underwent coronary artery bypass graft surgery (CTO bypassed in 88%). Percutaneous coronary intervention was done in 30% of patients, although CTO lesions were attempted in only 10% (with 70% success rate). CONCLUSIONS: Chronic total occlusions are common in contemporary catheterization laboratory practice. Prospective studies are needed to ascertain the benefits of treatment strategies of these complex patients.