1. A method for generating a statistic for phone lengths, with which the phone lengths can be controlled on the basis of this statistic during synthetic speech generation, comprising: assigning phones of a spoken and recorded text that is segmented into phones, to phonemes of predetermined primary clusters composed of a plurality of phonemes, in each case one phone being assigned to a primary phoneme of one of the predetermined primary clusters if present in the spoken text in a context which is identical or similar to the context of the primary phoneme; producing a primary statistic including at least an average phone length of all the phones assigned to a corresponding phoneme of one of the predetermined primary clusters; assigning phones of the spoken and recorded text to phonemes of predetermined secondary clusters composed of phonemes, a number of phonemes of at least some secondary clusters differing from a number of phonemes of the predetermined primary clusters, in each case one phone being assigned to a secondary phoneme of one of the predetermined secondary clusters if present in the spoken text in a context which is identical to the context of the secondary phoneme; and producing a secondary statistic including at least an average phone length of all the phones assigned to the secondary phoneme.