Classification of heart valve sounds from experiments in an anechoic water tank

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In vivo studies in both sheep and humans were plagued by a number of problems including movement artifacts, biological noise, low signal-to-noise ratio (SNR), chest-wall reverberation, and limited bandwidth recordings as discussed by [1]. To overcome these problems it was decided to record heart valve sounds under controlled conditions deep in an anechoic water tank, free from reverberation noise, including surface reflections. Experiments were conducted in a deep water tank at the Transdec facility in San Diego, which satisfies these requirements. The Transdec measurements are free of reverberations, but not totally free of acoustic and electrical noise. We used a ... continued below

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835 Kilobytes pages

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Axelrod, M C; Clark, G A & Scott, D June 1, 1999.

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Description

In vivo studies in both sheep and humans were plagued by a number of problems including movement artifacts, biological noise, low signal-to-noise ratio (SNR), chest-wall reverberation, and limited bandwidth recordings as discussed by [1]. To overcome these problems it was decided to record heart valve sounds under controlled conditions deep in an anechoic water tank, free from reverberation noise, including surface reflections. Experiments were conducted in a deep water tank at the Transdec facility in San Diego, which satisfies these requirements. The Transdec measurements are free of reverberations, but not totally free of acoustic and electrical noise. We used a high quality hydrophone together with a wide-band data acquisition system [2]. We recorded sounds from 100 repetitions of the opening-closing cycles on each of 50 different heart valves, including 21 SLS valves and 29 intact valves. The power spectrum of the opening and closing phases of each cycle were calculated and outlier spectra removed as described by Candy [2]. In this report, we discuss the results of our classification of the heart valve sound measurements. The goal of this classification task was to apply the fundamental classification algorithms developed for the clinical data in 1994 and 1996 to the measurements from the anechoic water tank. From the beginning of this project, LLNL's responsibility has been to process and classify the heart valve opening sounds. For this experiment, however, we processed both the opening sounds and closing sounds for comparison purposes. The results of this experiment show that the classifier did not perform well. We believe this is because of low signal-to-noise ratio and excessive variability in signal power from beat-to-beat for a given valve.

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835 Kilobytes pages

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  • Other Information: PBD: 1 Jun 1999

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  • Report No.: UCRL-ID-134634--Rev-1
  • Report No.: AC1005000
  • Grant Number: W-7405-ENG-48
  • DOI: 10.2172/10788 | External Link
  • Office of Scientific & Technical Information Report Number: 10788
  • Archival Resource Key: ark:/67531/metadc626613

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  • June 1, 1999

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  • June 16, 2015, 7:43 a.m.

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  • May 6, 2016, 3:15 p.m.

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Axelrod, M C; Clark, G A & Scott, D. Classification of heart valve sounds from experiments in an anechoic water tank, report, June 1, 1999; California. (digital.library.unt.edu/ark:/67531/metadc626613/: accessed September 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.