  Using the idea of local entropy theory, we characterize the sequence entropy
tuple via mean forms of the sensitive tuple in both topological and
measure-theoretical senses. For the measure-theoretical sense, we show that for
an ergodic measure-preserving system, the $\mu$-sequence entropy tuple, the
$\mu$-mean sensitive tuple and the $\mu$-sensitive in the mean tuple coincide,
and give an example to show that the ergodicity condition is necessary. For the
topological sense, we show that for a certain class of minimal systems, the
mean sensitive tuple is the sequence entropy tuple.
