Rocktron Reaction HUSH - Manual (Page 11)

HUSH Information
When downward expansion begins, the VCA acts
like an electronic volume control and gradually
begins decreasing the output signal relative
to the input signal. For example, if the input
signal were to drop below the threshold point
by 10dB, the output would drop approximately
12dB. As the input signal drops further below the
threshold point, downward expansion increases
exponentially. This means that if the input signal
dropped 20dB below the threshold point, the output
level would drop approximately 30dB. A 30dB
drop below the threshold would result in a drop of
60dB of the output signal (30dB of gain reduction).
The absence of any input signal will result in the
expander reducing the gain so that the noise floor
is inaudible.