1. An apparatus for supporting design of a speech interface, wherein the speech interface accepts a plurality of speech control options, the apparatus comprising: speech samples stored on a computer-readable medium; a similarity calculating unit configured to calculate a certain indication of similarity of first and second sets of ones of the speech samples, the first set of speech samples being associated with a first speech control option and the second set of speech samples being associated with a second speech control option; and a display unit configured to display the similarity indication.