## 3 Results  
### Descriptive Analysis  
Figure 2 presents the frequency distribution of the variables relevant to the database used in this study. In terms of gender, there were more females than males, and for smoking status, the majority were non-smokers. Regarding alcohol consumption, there were more non-drinkers, though a significant number of participants consumed alcohol. The proportion of voice users and non-users was nearly equal, and more participants drank coffee than those who did not. There were more individuals without comorbidities and, in terms of surgery status, slightly more participants had not undergone surgery, with a small number having undergone laser microlaryngeal surgery (LMS). Lastly, more participants had received voice training compared to those who had not. The following graphs help in comparing and understanding the demographic and lifestyle characteristics of the subjects in the database. Figure 1: Research process flowchart of this study. Figure 3 presents a boxplot comparing the distribution of VHI scores across four categories (F, P, E, and T) before and after voice therapy. In this context, F denotes functional scores, P represents physical scores, E corresponds to emotional scores, and T signifies the total VHI score. Each category reflects a specific dimension of the VHI assessment, and the boxplot visually represents the median, interquartile range, minimum and maximum values, as well as outliers. Under the pre-therapy (\"Before\") condition, the T category exhibits a notably high median score, with a wide range of distribution; however, under the post-therapy (\"After\") condition, the median score decreases significantly, and the variability is markedly reduced. The P category, which initially shows a relatively high median and broad distribution under the \"Before\" condition, also experiences reductions in both the median score and the range of distribution under the \"After\" condition. The F and E categories maintain low medians and narrow distributions across both conditions, indicating minimal score variability. Overall, the T category demonstrates a substantial reduction in scores following the intervention, while the other categories (F, P, E) also show decreases in score distributions or reduced variability under the \"After\" condition. Ultimately, the lower scores across all categories following voice therapy suggest that most individuals perceived an improvement in the quality of their voice after undergoing treatment. Figure 2: Histogram distributions of multiple variables categorized by participant status. Figure 4 consists of four histograms, each illustrating the effectiveness of therapy on AHI scores across different dimensions. The histograms are divided into two categories: \"Effectiveness \(-\) \" and \"Effectiveness \(+\)\", representing cases in which therapy was ineffective and effective, respectively. The first histogram (a) displays the distribution of total AHI scores, with 93 samples in the \"Effectiveness \(+\)\" category, indicating that most participants experienced positive changes following therapy. The second histogram (b) shows the distribution of functional scores, where 78 samples fall into the \"Effectiveness \(+\)\" category, suggesting significant improvements in the functional aspect for many participants. The third histogram (c) depicts the distribution of physical scores, with 96 samples in the \"Effectiveness \(+\)\" category, demonstrating that most participants experienced positive physical changes post-therapy. Lastly, the fourth histogram (d) represents the distribution of emotional scores, with 73 samples in the \"Effectiveness \(+\)\" category, indicating that therapy also had a beneficial impact on the emotional dimension. Overall, these four histograms indicate that therapy was effective across various aspects of the AHI, with the majority of participants showing improvement after treatment.