Automated Analysis of Crackles in Patients with Interstitial Pulmonary Fibrosis

Figure 1

The waveform of a typical crackle (a). The crackle analysis starts by identification of the crackle’s highest deflection highest peak. The half-period to the left of the highest peak is marked as 𝑇₁. The half-period to the right of the highest peak is marked as 𝑇₂. Crackle pitch is calculated from 4 consecutive half-periods, with 𝑇₁ as a 1st half-period. The amplitude is determined separately for each half-period and marked as 𝐴₁, 𝐴₂, and 𝐴₃. Crackle polarity (b) crackle polarity is defined positive if the highest peak is upward (c). Crackle polarity is defined negative if the highest peak is downward.

(a)

(b)

(c)