{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:42:01Z","timestamp":1785804121836,"version":"3.56.0"},"reference-count":26,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2021,10,12]],"date-time":"2021-10-12T00:00:00Z","timestamp":1633996800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Health and Welfare","award":["HI18C2383"],"award-info":[{"award-number":["HI18C2383"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In surgeries where general anesthesia is required, the auscultation of heart and lung sounds is essential to provide information on the patient\u2019s cardiorespiratory system. Heart and lung sounds can be recorded using an esophageal stethoscope; however, there is huge background noise when this device is used in an operating room. In this study, a digital esophageal stethoscope system was designed. A 3D-printed case filled with Polydimethylsiloxane material was designed to hold two electret-type microphones. One of the microphones was placed inside the printed case to collect the heart and lung sound signals coming out from the patient through the esophageal catheter, the other was mounted on the surface of the case to collect the operating room sounds. A developed adaptive noise canceling algorithm was implemented to remove the operating room noise corrupted with the main heart and lung sound signals and the output signal was displayed on software application developed especially for this study. Using the designed case, the noise level of the signal was reduced to some extent, and by adding the adaptive filter, further noise reduction was achieved. The designed system is lightweight and can provide noise-free heart and lung sound signals.<\/jats:p>","DOI":"10.3390\/s21206757","type":"journal-article","created":{"date-parts":[[2021,10,13]],"date-time":"2021-10-13T06:38:41Z","timestamp":1634107121000},"page":"6757","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Heart and Lung Sound Measurement Using an Esophageal Stethoscope with Adaptive Noise Cancellation"],"prefix":"10.3390","volume":"21","author":[{"given":"Nourelhuda","family":"Mohamed","sequence":"first","affiliation":[{"name":"Biomedical Science and Engineering Department, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyun-Seok","family":"Kim","sequence":"additional","affiliation":[{"name":"Biomedical Engineering Research Center, Asan Institute for Life Science, Asan Medical Center, Seoul 05505, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kyu-Min","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul 05505, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manal","family":"Mohamed","sequence":"additional","affiliation":[{"name":"Biomedical Science and Engineering Department, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung-Hoon","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul 05505, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1010-7712","authenticated-orcid":false,"given":"Jae Gwan","family":"Kim","sequence":"additional","affiliation":[{"name":"Biomedical Science and Engineering Department, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,12]]},"reference":[{"key":"ref_1","unstructured":"Rice, M.L., and Doyle, D.J. 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