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Design and Construction of a Cost Effective Headstage for Simultaneous Neural Stimulation and Recording in the Water Maze

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Diaphragm Design for an Electret Microphone Stethoscope.

Alex Gaudio¹, Helena Hahn¹, James West¹

¹department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 20218 USA.

IEEE Sensors Journal

|August 21, 2025

Summary

This summary is machine-generated.

Adding a hole to a digital stethoscope diaphragm improves lung sound signal quality and reduces noise. This innovation enables the creation of a high-quality, low-cost digital stethoscope using 3-D printing.

Keywords:

Acoustics auscultation digital stethoscope electret microphone signal fidelity

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The Measurement of Unsteady Surface Pressure Using a Remote Microphone Probe

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Area of Science:

Biomedical Engineering
Acoustics
Materials Science

Background:

Acoustic impedance matching is crucial for signal pickup in stethoscopes.
Traditional models often consider only one material interface, which may be insufficient for digital stethoscopes with electret microphones and air gaps.
Electret microphones introduce complexity due to multiple material interfaces.

Purpose of the Study:

To investigate design elements of digital stethoscopes for improved signal fidelity.
To evaluate the impact of a diaphragm hole on signal quality and ambient noise.
To develop novel metrics for assessing signal quality and noise leakage.

Main Methods:

Empirical testing of a 3-D printed electret stethoscope with a diaphragm hole.
Development and application of signal fidelity and noise leakage statistics based on empirical distance correlation.
Systematic evaluation of four diaphragm materials, six thicknesses, and diaphragm hole presence/absence on lung sound quality using an acoustic phantom in various noise conditions.

Main Results:

A hole in the electret stethoscope diaphragm significantly improves signal quality across different settings.
The proposed signal quality score and amplitude spectrum effectively evaluate performance.
The study identified optimal combinations of diaphragm materials and thicknesses for enhanced signal quality.

Conclusions:

Introducing a hole in the diaphragm simplifies the acoustic impedance matching problem and enhances signal quality.
The developed metrics provide a robust method for evaluating digital stethoscope performance.
A high-quality, low-cost ($5) digital stethoscope can be fabricated using 3-D printing and readily available components.