This study explored the influence of several factors, physical and human, on anisochrony's thresholds measured with an adaptive two alternative forced choice paradigm. The effect of the number and duration of sounds on anisochrony discrimination was tested in the first experiment as well as potential interactions between each of these factors and tempo. In the second experiment, the tempo or the inter onset interval (IOI) was varied systematically between 80 and 1000 ms. The results showed that just noticeable differences increase linearly and proportionally with IOI in accordance with Weber's law except for quickest tempo (IOI of 80 ms). The third experiment investigated the role of musical training on anisochrony thresholds obtained for different IOI. It focused on differential effects of musical experiences by comparing non-musicians, instrumentalists, and percussionists thresholds. The results of the present study replicated the findings of previous experiments regarding the adequacy of Weber's law for slow rhythm and provided evidence for its departure for fast tempos. Moreover, thresholds from percussionists seem distinguishable from the ones of other listeners by their highest sensitivity to temporal shifts suggesting therefore the necessity to control the nature of musical experiences. The results are discussed according to current models of time perception.