Abstract: A method for assessing quality of conversational speech between nodes of a communication network (1), comprising establishing a voice communication session via the communication network (1) between a user at a user terminal (2) and a virtual subject system (4), the virtual subject system (4) and user terminal (2) being connected to the communication network (1), the user terminal enabling the user to communicate by voice with the virtual subject system (4), during the session, acting as a conversation partner in a voice conversation with the virtual subject system (4), the virtual subject system being equipped with a speech generation module (42) to enable speaking during the session and a voice recognition module (41) to enable interpreting speech of the user during the session, and assessing the quality of speech over the communication network based on the voice conversation during the session, the assessing being performed by the user.