Browsing by Subject "Auscultation"

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Open Access
COVID-19 Detection from respiratory sounds with hierarchical spectrogram transformers
(Institute of Electrical and Electronics Engineers, 2023-12-05) Aytekin, Ayçe İdil; Dalmaz, Onat; Gönç, Kaan; Ankishan, H.; Sarıtaş, Emine Ülkü; Bağcı, U.; Çelik, H.; Çukur, Tolga
Monitoring of prevalent airborne diseases such as COVID-19 characteristically involves respiratory assessments. While auscultation is a mainstream method for preliminary screening of disease symptoms, its util ity is hampered by the need for dedicated hospital visits. Remote monitoring based on recordings of respi ratory sounds on portable devices is a promising alter native, which can assist in early assessment of COVID-19 that primarily affects the lower respiratory tract. In this study, we introduce a novel deep learning approach to distinguish patients with COVID-19 from healthy controls given audio recordings of cough or breathing sounds. The proposed approach leverages a novel hierarchical spectro gram transformer (HST) on spectrogram representations of respiratory sounds. HST embodies self-attention mech anisms over local windows in spectrograms, and window size is progressively grown over model stages to capture local to global context. HST is compared against state-of the-art conventional and deep-learning baselines. Demon strations on crowd-sourced multi-national datasets indicate that HST outperforms competing methods, achieving over 90% area under the receiver operating characteristic curve (AUC) in detecting COVID-19 cases.
Open Access
Model based analysis of the variation in Korotkoff sound onset time during exercise
(Institute of Physics Publishing, 2001) Türkmen, A.; Ider, Y. Z.
In this study, a minimal mathematical model of the cardiovascular system is used to study the effects of changes in arterial compliance and cardiac contractility on the onset time of Korotkoff sounds during an auscultatory procedure. The model provides blood pressure waveforms in the ventricle, the aorta and the brachial artery. From these waveforms, pre-ejection time, pulse propagation time and rise time of the blood pressure at the brachial artery can be computed. The time delay between onset time of ECG Q wave and onset time of Korotkoff sound is the sum of these three times. Rise time is zero and the time delay is minimal when the cuff pressure is slightly above the diastolic pressure. This minimum time delay is represented by QKD. Simulation results suggest that during the Bruce exercise protocol QKD decreases to one-third of its pre-exercise value if the cardiac contractility increases threefold. The effect of arterial compliance is not as significant as that of the cardiac contractility. From data recorded during an exercise test, it is observed that QKD decreases considerably as the test load is increased. We show in this study that the amount of decrease in QKD can be used as an index of the amount of increase in cardiac contractility during an exercise ECG test. Use of signal averaging for reducing the effect of motion artifacts during an exercise test is also shown to be very instrumental for making accurate QKD measurements.