Introduction Subjective voice analysis represents a diagnostic tool in phoniatry and is a part of everyday practice if a phoniatrist has a 'trained ear'. Material and methods This clinical prospective study included a sample of 20 male patients with malignant tumors involving one vocal cord - right or left. All patients underwent otorhinolaryngological and phoniatric examinations. Subjective acoustic analysis was done when patients pronounced numbers from 1 to 10. Afterwards, voice quality was evaluated separately by two professionals using a 4-levels scale: RBH scale (roughness-breathiness-hoarseness) and GIRBAS scale (grade-instability-roughness-breathiness-asthenia-strain). Results 60% of patients presented with vocal cord immobility. Subjective acoustic analysis revealed hoarseness in 100% of patients (the most frequent value was Mod=3 intense hoarseness in 45% patients). Instability existed in 100% of patient (40% moderate, 40% intense). Strained voice existed in 100%, most frequently intense (45%). Conclusions All patients with glottic carcinoma presented with hoarseness, strain and instability of phonation. Non vibration of vocal cord significantly affects the degree of dysphonia, roughness, strain and instability. Aerodynamic changes affect voice hoarseness. RBH scale is simple, but GIRBAS scale described more psyhoacoustic phenomena most important in patients with glottic carcinoma.