# A Progressively Expanded Database for Automated Lung Sound Analysis: An Update
## 3 Results
### Review of Label Quality  
Figure 7 illustrates the spectrograms (top graphs in Figure 7a-e) and labels (bottom graphs in Figure 7a-e) of five lung sound recordings. The quality of I and E labels was acceptable. In most cases, inhalations and exhalations can be clearly heard and identified, such as in the example displayed in Figure 7a. However, we can occasionally see wrong labels, such as the exhalation indicated by the white arrow in Figure 7b, or debatable labels, such as the exhalations indicated by the blue arrows in Figure 7b. An exhalation was sometimes not identifiable, such as the sound displayed in Figure 7c.  
However, the quality of C labels was unsatisfactory. CASs were often found unlabeled, such as the ones (green arrows) in Figure 7c. In some cases, the labelers were unsure whether to label a borderline case. For example, the labeler did not label the sound indicated by the first green arrow in Figure 7d but labeled the sounds indicated by the second and third green arrows although these sounds did not form clear streak patterns on the spectrogram.  
Figure 6: ROC curves of the V1_Train-based and V2_Train-based models tested using V1_Test for (**a**) inhalation, (**b**) exhalation, (**c**) CAS, and (**d**) DAS segment detection and using V2_Test for (**e**) inhalation, (**f**) exhalation, (**g**) CAS, and (**h**) DAS segment detection. Solid lines represent the ROC curves, and the colored shades represent areas between the 95% confidence intervals. The blue lines and blue shades stand for the models trained using V1_Train, and the red lines and red shades stand for the models trained using V2_Train. The values in the parentheses in the legends indicate the mean AUC.  
Figure 7: Spectrograms (top) and labels (bottom) of five lung sound recordings. In the label graphs at the bottom, red squares with the letter “I” represent I labels. By the same logic, blue squares with the letter “E” represent E labels, purple squares with the letter “D” represent D labels, and green squares with the letters “S,” “W,” and “R” represent S, W, and R labels, respectively. The blue arrows in (**b**) indicate two sounds with debatable E labels. The white arrow in (**b**) indicates that an inhalation was incorrectly labeled as E. The green arrows in (**c**) indicate CASs that were left without a correct S, W, or R label. The green arrows in (**d**) indicate the sound recordings that did not form clear streak patterns. The purple arrow in (**e**) indicates some noises that interfered with DAS labeling. The white dashed squares in (**a**,**c**,**d**) indicate sound events that were left without a label at the beginning and end of a lung sound recording.  
Regarding the quality of D labels, even experts could not arrive at a consensus on the correct labeling of a given DAS. For instance, many noises may have DAS-like patterns and may interfere with the labeling process (purple arrow in Figure 7e). Furthermore, the DAS patterns in Figure 7b are sometimes not as clear as those displayed in Figure 7e.  
The density plots of the start and end times of I, E, C, and D labels in the V2_Train and V2_Test are displayed in Figure 8. The density of the start and end times of the I (blue lines in Figure 8a-d), E (orange lines in Figure 8a-d), C (green lines in Figure 8a-d), and D (red lines in Figure 8a-d) labels was lower at the beginning and end of the lung sound recordings. However, the density curves reached a higher plateau roughly between 1-14 s for all I, E, C, and D labels in the V2_Train (blue, orange, red, and green lines in Figure 8a,b), though the density curves of I, E, and D labels fluctuated between 1-14 s in the V2_Test (blue, orange, and green lines in Figure 8c,d).