Acoustic Methods for Pulmonary Diagnosis

Listening and interpreting of lung sounds by a stethoscope had been an important component of screening and diagnosing lung diseases. However this practice has always been vulnerable to poor audibility and poor reproducibility because of their low signal-to-noise ratio as lung sounds have relatively low amplitude compared with background noise of heart and muscle sounds. The main objective of this project is to design a system for detection of lung sounds. Lung sounds can be classified as normal sounds and adventitious sounds (abnormal sounds). Normal sounds are tracheal breath sounds and normal vesicular breath sounds.

Journal of Medical Systems, 2000

Listening to various lung sounds has proven to be an important diagnostic tool for detecting and monitoring certain types of lung diseases. In this study a computerbased system has been designed for easy measurement and analysis of lung sound using the software package DasyLAB. The designed system presents the following features: it is able to digitally record the lung sounds which are captured with an electronic stethoscope plugged to a sound card on a portable computer, display the lung sound waveform for auscultation sites, record the lung sound into the ASCII format, acoustically reproduce the lung sound, edit and print the sound waveforms, display its time-expanded waveform, compute the Fast Fourier Transform (FFT), and display the power spectrum and spectrogram.

2013

pulmonary diseases are major causes of ill-health throughout the world. Pulmonary infection such as acute bronchitis and pneumonia are common. The diagnosis of these diseases is facilitated by pulmonary auscultation using stethoscope which has many limitations such that it depends on individuals own hearing, experience and ability to differentiate between the different sounds (1).The quantitative measurement and permanent record of the diagnosed diseases is difficult. The computerized methods for recording and analysis of the respiratory sounds may overcome some of limitations of auscultation using stethoscope. An analysis of respiratory sounds may quantify the changes in different respiratory acoustic in various diseases. The use of modern digital signal processing technique may lead deep insight to get related diagnostic information (2) (3). Most of the respiratory sound energy is concentrated in the frequencies below 200 Hz, which overlap with the main frequency components of the...

2010

In this paper a new pressure sensor-based electronic device for the analysis of lung sounds has been designed and prototyped. The device allows the effective auscultation, the accurate processing and the detailed visualization (temporal and frequency graphs) of any lung sound. Moreover it is suitable for the continuous real-time monitoring of breathing functions, resulting very useful to diagnose respiratory pathologies. It provides medical specialists with a totally noninvasive high-engineering device able to detect and analyze the widest number of data for the monitoring of the respiratory system by the simple recording and evaluation of lung sounds being a substantiated correlation between lung sounds and diseases.

Chest

We assessed the performance of three air-coupled and four contact sensors under standardized conditions of lung sound recording. Recordings were obtained from three of the investigators at the best site on the posterior lower chest as determined by auscultation. Lung sounds were band-pass filtered between 100 and 2,000 Hz and sampled simultaneously with calibrated airflow at a rate of 10 kHz. Fourier techniques were used for power spectral analysis. Average spectra for inspiratory sounds at flows of 2 +/- 0.5 L/s were referenced against background noise at zero flow. Air-coupled and contact sensors had comparable maximum signal-to-noise ratios and gave similar values for most spectral parameters. Unexpectedly, less sensitivity (lower signal-to-noise ratio) at high frequencies was observed in the air-coupled devices. Sensor performance needs to be characterized in studies of lung sounds. We suggest that lung sound spectra should be averaged at known airflows over several breaths and ...

Computers in Biology and Medicine, 2008

Auscultation of pulmonary sounds provides valuable clinical information but has been regarded as a tool of low diagnostic value due to the inherent subjectivity in the evaluation of these sounds. In this work, a Digital Signal Processor is used to design an instrument capable of acquiring, parameterizing and subsequently classifying lung sounds into two classes with an aim to evaluate them objectively in real time. The instrument operates on sound signal from a chest microphone and flow signal from a pneumotachograph. The classification is carried out separately on the 12 reference libraries (pathological and healthy) of six sub-phases of a full respiration cycle and the results are combined to arrive at a final decision. The k-nearest neighbour and minimum distance classifiers with different distance metrics have been implemented in the instrument. The instrument was tested in the clinical environment, attaining 96% accuracy in real-time classification.

Abstract: The most important concern in the medical domain is to consider the interpretation of data and perform accurate diagnosis.The bronchitis, pneumonia and many other pulmonary diseases causes respiratory disorders which affects respiratory systems. Diagnosis of these diseases is facilitated by pulmonary auscultation by using stethoscope. This method depends on individuals hearing capability, experience and ability to differentiate the sounds. The quantitative measurement and permanent record of the related parameters is difficult. The recording and analysis of the respiratory sounds may quantify the changes in abnormal respiratory sounds in respiratory disorder. The signal processing techniques may be used for diagnostic information. Keywords: bronchitis, pneumonia, pulmonary auscultation, respiratory sound, respiratory disorder etc

The Open Anesthesia Journal

This brief review introduces the reader to some of the various historical and modern methods that are available for the bio-acoustical assessment of patient breathing, with other bio-acoustical processes discussed peripherally. Some simple methods of respiratory assessment of historical interest are first discussed, along with more modern methods of patient acoustical monitoring based on advanced analytic methods.

The Open Anesthesia Journal

This paper introduces the reader to some of the various methods that are available for the time-domain bio-acoustical monitoring of patient breathing. Technical details concerning microphone selection, calibration and characterization, signal amplification, signal filtering and waveform recording are presented. We also describe proof of concept recordings obtained from the neck, from the external ear canal, from a microphone embedded into an oxygen mask and from a leak-free microphone pneumatically connected to the cuff of a laryngeal mask airway. We recommend Audacity, an open-source digital audio editor and recording package that can be freely downloaded at https://www.audacityteam.org for investigators seeking to conduct research on breath sound analysis.

Medical & Biological Engineering & Computing, 1995