The interval of a burst at level j in the hierarchy of bursts is the maximal interval during which the optimal state sequence is in state j or higher, i.e., k > j, thus forming a hierarchical organization of burst intervals.
a word considered bursty on a time interval [a, b] with a burstiness level of i is simultaneously considered as busty at a level i−1 on an interval This hierarchy is illustrated in Figure 4 for one word: The word occurs with a burstiness level of 1 on the first utterances, with an important amount of occurrences at the very beginning yielding a short interval at level 2 included in the interval at level 1.