A system for performing magnetic resonance tomography is disclosed. A control system creates a speech data stream from an acquired linguistic expression and generates a command library, which contains a selection of speech commands, to each of which one or more linguistic expressions are assigned. The selection of speech commands is loaded from a command database depending on a current system status of a magnetic resonance (MR) scanner. The control system applies a speech recognition algorithm to the speech data stream to determine whether a linguistic expression contained in the command library can be assigned to the speech data stream. If so, the acquired linguistic expression is recognized, a speech command from the command library assigned to the recognized linguistic expression is established, and a control command for controlling the MR scanner in accordance with the speech command is created.