The testing error and the reason of error are analyzed, compared with the results received by the sweep-frequency measurement method.

The bats can also "sweep through a frequency range of up to 170 kilohertz, " moving from lower to higher notes, "while a human singer produces a glissando through less than 2 kilohertz at most."

In this paper several dynamic testing methods of electrohydraulic servo systems are introduced, including stochastic noise test, hammering test and sweep frequency test.