Characteristics of flow standardized inspiratory lung sounds in healthy

: Objectification of respiratory sounds, recorded on chest surface, is important to assess human broncho-pulmonary system. The aim is to detail the objective characteristics of basic inspiratory sounds. The study involved 36 healthy men aged 19 to 80 years. Under flow rate 0.89 ± 0.18 L/s medians of spectral characteristics of basic inspiratory lung sounds are in the ranges: amplitude level -63.3... -56.5 dB, -3 dB cutoff frequency 269.5-359.4 Hz, -20 dB cutoff frequency 531.3-621.1 Hz, the slope of the spectrum curve between the cut-off frequencies -0.077... -0.050 dB/Hz. The high degree of bilateral symmetry of spectral characteristics is found. Significant upward trend in the cutoff frequencies is revealed between interscapular region and apices or basal areas of the lungs. The 90% limits of intersubject variability of the cutoff frequencies of the spectrum are identified in areas of chest used for lung auscultation.