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Asthma is a disease of air flow obstruction. Transmitted sounds can be analyzed in detail and may shed light upon the physiology of asthma and how it changes over time. The goals of this study were to use a computerized analytic acoustic tool to evaluate respiratory sound patterns in asthmatic patients during acute attacks and after clinical improvement and to compare asthmatic profiles with those of normal individuals.Respiratory sound analysis throughout the respiratory cycle was performed on 22 symptomatic asthma patients at the time of presentation to the emergency department (ED) and after clinical improvement. Fifteen healthy volunteers were analyzed as a control group. Vibrations patterns were plotted. Right and left lungs were analyzed separately.Asthmatic attacks were found to be correlated with asynchrony between lungs. In normal subjects, the inspiratory and expiratory vibration energy peaks (VEPs) occurred almost simultaneously in both lungs; the time interval between right and left expiratory VEPs was 0.006 +/- 0.012 seconds. In symptomatic asthmatic patients on admission, the time interval between right and left expiratory VEPs was 0.14 +/- 0.09 seconds and after clinical improvement the interval decreased to 0.04 +/- 0.04 seconds. Compared to healthy volunteers, asynchrony between two lungs was increased in asthmatics (p0.05). The asynchrony was significantly reduced after clinical improvement (p0.05).Respiratory sound analysis demonstrated significant asynchrony between right and left lungs in asthma exacerbations, a finding which, to our knowledge, has never been reported to date. The asynchrony is significantly reduced with clinical improvement following treatment.

The intensity of acoustic stimulation is frequently a variable of interest in psychophysiological studies but calibration procedures, particularly when earphones are employed, are not always adequate. The present study demonstrates that intensity is underestimated, more seriously at low frequencies, when calibration does not employ an appropriate coupler. Several standardized calibration methods are discussed in terms of their suitability For routine laboratory use.