RMS is a first-approximation for the desibilator threshold,
if there is lisping with the threshold at RMS value,
try raising the threshold from the RMS value in 1dB steps until the lisping goes away.
e.g. if the RMS is -20dB, but preview sounds lispy, try -19dB, -18dB, etc
I would use a real-time equalizer plugin, e.g.
so I could hear the effect of adjusting the bass as the track played.
IMO attenuate everything below 200Hz, (not just a dip between 100-200),
as some people will be able to hear <100Hz, depending on the device they are listening on.
It sounds like clicking is occurring in the mic, (rather than in your mouth).
Paul-L’s is the only free de-clicker plugin I know of.