J. D. Lawson, M.D. (Associate)
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When ultra high-frequency, high-speed phonocardiography was studied, it became clear that the traditional methods employed to display the heart sounds were inadequate for precise observations concerning sound intensity, splitting of valve sounds, and meaningful geometrical analysis of murmur configuration.
To overcome these difficulties, a new method for displaying the heart sounds was devised, which has subsequently been modified for use with a standard ECG machine for registration.
Previous attempts to record the phonocardiogram with a standard ECG were unsatisfactory due to the limited high frequency response of such machines (50 to 120 cps). With the present apparatus, which costs less
Lawson JD. The Hemienvelope Phonocardiogram.. Ann Intern Med. ;58:710–711. doi: 10.7326/0003-4819-58-4-710_2
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Published: Ann Intern Med. 1963;58(4):710-711.
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