3.2, The Evaluation of the breath sound spectrogram
On comparing the respiratory sounds of patients in the recovery period and a seven-month-old healthy infant from a previous study15) to those of patientsint the acute phase of acute bronchiolitis, the sound power of inspiration and expiration in the acute phase were great, especially that of expiration (Figure 1).
An examination of the breath sound spectrogram images of all the patients showed sinusoidal waveforms of wheezes (>400 Hz, >200mS) in 11 (33 %), sinusoidal waveforms of rhonchi (≤200 Hz, >200mS) in 7 (21 %), and non-uniform, granular bands suggesting strong power in the low-pitched region of the expiratory spectrum (Figure 1) in 20 (61%, 5 cases overlapped with wheezes or rhonchi). As a typical case of this sound, the sound spectrum on expiration in one patient showed a waveform with several peaks (Figure 2).