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Related Experiment Videos

Improved phonocardiogram system based on acoustic impedance matching

R S Schwartz, J T Reeves, I E Sodal

    The American Journal of Physiology
    |April 1, 1980
    PubMed
    Summary

    This study introduces an improved phonocardiographic recording device that enhances heart sound signal acquisition. The new instrument offers superior performance and greater information content compared to existing commercial devices.

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    Area of Science:

    • Biomedical Engineering
    • Cardiology
    • Acoustics

    Background:

    • Phonocardiography is crucial for diagnosing heart conditions.
    • Current phonocardiographic devices face limitations in signal quality due to acoustic impedance mismatch and suboptimal transducer design.
    • Digital signal storage is essential for detailed analysis.

    Purpose of the Study:

    • To develop an improved phonocardiographic recording instrument.
    • To enhance signal acquisition by minimizing acoustic impedance mismatch.
    • To optimize transducer configuration and incorporate digital signal storage.

    Main Methods:

    • Minimizing acoustic impedance mismatch between precordial tissue and transducer.
    • Optimizing the impedance-matching medium and transducer design, utilizing an aqueous coupling medium and a concentrating horn configuration.

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  • Employing analog-to-digital conversion for digital signal storage.

    • Main Results:

    • Signal voltage increased approximately 100-fold with the aqueous coupling medium.
    • The new device demonstrated superior frequency response (1 Hz to 1 kHz) compared to commercial microphones.
    • Digitized, unfiltered signals showed excellent beat-to-beat repeatability, preserving more information than conventional analog filtering.

    Conclusions:

    • The developed phonocardiographic instrument significantly outperforms tested commercial devices in recording heart sounds.
    • Optimizing acoustic coupling and employing digital recording are key to improving phonocardiography.
    • This enhanced device holds potential for more accurate cardiac auscultation and diagnosis.