Electronic Stethoscope Noise Cancellation Using Ambient Microphones
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Solution Overview
Problem
Acoustic stethoscopes suffer from attenuation of sound waves based on frequency, making it difficult to accurately diagnose conditions, while electronic stethoscopes face issues with digital artifacts and component cutoffs that limit their frequency response.
Innovation Solution
The electronic stethoscope system includes input units with conical resonators and dual microphones (auscultation and ambient) that simultaneously monitor internal and ambient sounds. A processor applies a noise cancellation algorithm to improve sound quality by filtering out artifacts and adjusting audio data based on ambient noise analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic stethoscope is used, then simple design and no digital artifacts are achieved, but sound attenuation proportional to frequency occurs making diagnosis difficult
Solution Approach 1:
The patent replaces the purely mechanical acoustic transmission system with an electronic system that uses microphones, amplifiers, and digital signal processing. This substitution allows electronic amplification to overcome the frequency-dependent attenuation inherent in acoustic stethoscopes, enabling reliable detection of low-frequency sounds while maintaining diagnostic accuracy.
Solution Approach 2:
The patent applies digital signal processing techniques including noise cancellation algorithms and frequency response adjustments to modify the acoustic parameters. By dynamically adjusting gain across different frequency bands and applying adaptive noise filtering, the system compensates for attenuation and enhances diagnostic reliability without introducing digital artifacts.
2Power
If electronic stethoscope with single downward-facing microphone is used, then internal sounds are amplified, but significant interference from ambient noise occurs
Solution Approach 1:
The patent segments the audio signal processing into multiple independent components: a primary microphone for internal sounds, secondary microphones for ambient noise capture, and separate processing channels for each. This segmentation allows independent analysis and cancellation of ambient noise while preserving the amplified internal sounds, solving the interference problem.
Solution Approach 2:
The patent introduces ambient noise microphones as intermediary sensors that capture environmental sounds separately. These intermediaries provide reference signals that feed into noise cancellation algorithms, which then subtract the ambient component from the primary audio signal, effectively isolating the internal body sounds from environmental interference.
3Measurement precision
If electronic stethoscope amplification is applied, then faint internal sounds are enhanced, but undesirable digital artifacts are introduced
Solution Approach 1:
The patent implements feedback mechanisms where the processed audio signal is continuously monitored and fed back into the noise cancellation algorithm. This feedback loop allows the system to adaptively adjust filtering parameters and gain settings in real-time, enhancing faint sounds while suppressing the generation of digital artifacts through iterative optimization.
Solution Approach 2:
The patent applies selective amplification rather than uniform amplification across all frequencies. By applying gain only to specific frequency bands where internal sounds are present and using adaptive noise cancellation on other bands, the system enhances detection sensitivity for faint sounds while minimizing the introduction of digital artifacts through excessive processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the clarity and detail of sound recordings by effectively canceling noise and improving the signal-to-noise ratio, thereby aiding in more accurate diagnosis.
Implementation Method 1
a conical resonator designed to direct acoustic sound waves toward an auscultation microphone
Implementation Method 2
The input unit may include at least one ambient microphone configured to produce audio data indicative of ambient sounds
Implementation Method 3
A processor applies a noise cancellation algorithm to improve sound quality by filtering out artifacts and adjusting audio data based on ambient noise analysis
Data Source
AI summary
Introduced here are electronic stethoscope systems designed to simultaneously monitor sounds originating from within a body under examination and the ambient environment. An electronic stethoscope system can include one or more input units that are connected to a hub unit. Each input unit may have at least one auscultation microphone and at least one ambient microphone. To improve the quality of sound recorded by an input unit, a processor can apply a noise cancellation algorithm that considers as input the audio data produced by the auscultation microphone(s) and the audio data produced by the ambient microphone(s). The audio data may be digitized directly in the input unit, and then transmitted to the hub unit for synchronization. For example, by examining the audio data produced by the ambient microphone(s), the processor may discover which digital artifacts, if any, should be filtered from the audio data produced by the auscultation microphone(s). The processor may reside within the input unit or the hub unit.