Recently, new ways of measuring rhythmic differences have been proposed. These are derived from syllable structure and prosodic differences between languages. The measurements are all durational: the variability of vocalic and consonantal intervals is calculated and plotted on two axes. Very small amounts of read material have been analysed. But the structural basis of the measurements implies dependency on the nature of the speech material: representativity problem. Tempo measurements are a function of phone- and syllable duration and must therefore be confounded with rhythm measures. This study presents a comparative rhythm analysis of spontaneous Italian and German. Some of these problems, in particular Speech Tempo, are discussed.