Acoustic Character Governing Variation in Normal, Benign, and Malignant Voices.

Introduction: Benign and malignant vocal fold lesions (VFLs) are growths that occur on the vocal folds. However, the treatments for these two types of lesions differ significantly. Therefore, it is imperative to use a multidisciplinary approach to properly recognize suspicious lesions. This study aimed to determine the important acoustic characteristics specific to benign and malignant VFLs.

Methods: The acoustic model of voice quality was utilized to measure various acoustic parameters in 157 participants, including individuals with normal, benign, and malignant conditions. The study comprised 62 female and 95 male participants (43 ± 10 years). Voice samples were collected at the Shanghai Eye, Ear, Nose, and Throat Hospital of Fudan University between May 2020 and July 2021. The acoustic variables of the participants were analyzed using Principal Component Analysis (PCA) to present important acoustic characteristics that are specific to normal vocal folds, benign VFLs, and malignant VFLs. The similarities and differences in acoustic factors were also studied for benign conditions including Reinke's edema, polyps, cysts, and leukoplakia.

Results: Using the PCA method, the components that accounted for the variation in the data were identified, highlighting acoustic characteristics in the normal, benign, and malignant groups. The analysis indicated that coefficients of variation in root mean square energy were observed solely within the normal group. Coefficients of variation in pitch (F0) were found to be significant only in benign voices, while higher formant frequencies and their variability were identified as contributors to the acoustic variance within the malignant group. The presence of formant dispersion (FD) as a weighted factor in PCA was exclusively noted in individuals with Reinke's edema. The amplitude ratio between subharmonics and harmonics (SHR) and its coefficients of variation were evident exclusively in the polyps group. In the case of voices with cysts, both pitch (F0) and coefficients of variation for FD were observed to contribute to variations. Additionally, higher formant frequencies and their coefficients of variation played a role in the acoustic variance among voices of patients with leukoplakia.

Conclusion: Experimental evidence demonstrates the utility of the PCA method in the identification of vibrational alterations in the acoustic characteristics of voice affected by lesions. Furthermore, the PCA analysis has highlighted underlying acoustic differences between various conditions such as Reinke's edema, polyps, cysts, and leukoplakia. These findings can be used in the future to develop an automated malignant voice analysis algorithm, which will facilitate timely intervention and management of vocal fold conditions.