Introduction: Oral or oropharyngeal cancer affect the anatomical structures involved in speech production. Currently, speech assessment is mainly based on perceptual measurements, with many limitations in terms of reliability. The C2SI (Carcinologic Speech Severity Index) project allowed to buildan automatic, reliable and objective score for the severity of the speech disorder in these patients.Objective: To determine which specific speech parameters impact the severity of the speech disorder.Method: 87 subjects treated fororal or oropharyngealcancer were included. The automatic C2SI severity score was calculated for these subjects. A panel of six expert listeners perceptually assessed voice, resonance, prosody and phonemic production.Results: The perceptual evaluation of the specific speech parameters showed a moderate inter-judge agreement. A linear regression analysis performed on all subjects shows the impact of prosody (p=.02), resonance (p<.001) and phonemic production (p=.001) on the severity of the disorder (R2=.75). However, a stratified analysis bytumorlocation shows that if resonance explainsthe severity of the disorder whatever the location (p<.01), phonemic production contributes to the explanationonlyin case of oral tumor (p<.01), and prosody (p=.04) and voice (p=.03)onlyin case of oropharyngeal tumor.Discussion -Conclusion: The influence of the different specific speech parameters on the severity of the disorder differs according to the tumor location. An automaticextraction of these parameters would allow a better reliability of the evaluation, to adapt the therapeutic strategies closer to the needs of the patients. However, the measurement of the impact of the disorder on their communication abilitiesremains to be explored.