Abstract: A software-based diagnostic tool and a diagnostic system for diagnosing a chronic neurological disorder. The diagnostic tool includes a speech analysis module for identifying characteristic values of a vocal biomarker in a speech signal of a subject, a further module for identifying characteristic values of a second biomarker, and an evaluation unit. The speech analysis module includes: a speech-signal-triggering which displays image data on an image display to trigger a speech signal in the subject; a speech recording unit which records the speech signal; and a speech signal analyzer that evaluates the speech signal to determine first at what point in time which pitch level is present, and subsequently determine a frequency distribution of the pitch levels among a number of frequency bands of a selected frequency spectrum, with this frequency distribution forming the characteristic values of the vocal biomarker.