A comparison of the phonation quotient between patients with voice disorders caused by benign vocal fold lesions and normal adults 20-80 years of age

Background: A voice evaluation is an important first step in analyzing voice symptoms and determining appropriate treatment plans. The phonation quotient is a valid aerodynamic parameter in voice evaluations which is an indirect source of information for evaluating the valve function of the vocal folds of patients with voice disorders, especially patients with voice disorders caused by tumors of the vocal folds which is the most common cause in the patients with voice disorders. Objective: The present study aims to determine and compare the phonation quotient between patients with voice disorders caused by benign vocal fold lesions and normal adults between 20-80 years of age. Materials and methods: The participants comprised 40 adults with voice disorders caused by benign vocal fold lesions and 40 with normal voices. All participants’ voices were evaluated in the Speech Clinic at Ramathibodi Hospital, Bangkok. The phonation quotient (PQ) was calculated by the ratio of vital capacity (VC) to the maximum phonation time (MPT). VC and MPT were measured using a phonatory aerodynamic system (PAS). Results: The results of the present study indicated that the mean value of the PQ of adults with normal voices was 122.60 cc/sec (SD=16.36). The mean value of the PQ of adults with voice disorders caused by benign vocal fold lesions was 292.08 cc/ sec (SD=97.14). The mean value of the PQ in the group with voice disorders caused by benign vocal fold lesions was significantly more significant than the mean value of the PQ in the group with normal voice. Conclusion: The significant difference between the phonation quotient of adults with voice disorders caused by benign vocal fold lesions and adults with normal voice was that the PQ might be an indicator for indirect evaluation of the airflow leakage related to the efficiency of vocal fold movement during phonation. The PQ can be the optional voice measurement for monitoring and analyzing the outcomes of voice therapy.