You can listen to the signal again by clicking on plots.
Go back up a level to continue.
Does the spectrogram show any dominant frequency?
(No, it appears to have more or less the same gray color throughout.)
Notice that the time waveform is unpredictable, i.e., random.
It can be synthesized in MATLAB with the randn(m,n) function.
Go back up a level to continue.
