ABSTRACT
The spectral content of recorded breath sounds is determined by three elements: the frequency content of the actual breath sounds; the influence of background sounds produced in the thorax and ambient noises; and the frequency response of the equipment used for pickup, amplification, filtration, and analog-to-digital conversion. The average spectrum of normal adult breath sounds has one distinct pattern for the tracheal sounds and another for chest wall sounds. The spectral patterns of breath sounds just described for adults is also seen in children. The average spectrum of chest wall sounds over a region of lung sounds with consolidation has a pattern resembling that of normal tracheal breath sounds. The breath sounds spectra of the emphysema patients had an essentially normal pattern at all the chest wall pickup locations. Wheezing breath sounds have power spectra with sharp and narrow peaks. The acoustic content of normal heart sounds is concentrated in low frequencies.
