LinuxMusicians

Can anyone recommend a good noise gate for pulse audio?

In theory, any LADSPA plugin that will work in JACK can be loaded as a Pulseaudio module

In practice, the command to load LADSPA module requires a list of numbers for the variables needed for DSP settings Not aware of any DSP host for gui control of DSP, so DSP can only be loaded with fixed settings via terminal command.
To do this requires knowing the LADSPA plugin well enough to create the list of options in correct order.

If you want to only use Pulseaudio, I would still suggest starting with DSP in a JACK host to fine tune settings in a gui, then transfer the settings values to Pulseaudio module command. But if you are going to use JACK it makes more sense (IMO) to keep the DSP in the sound server built for that task and just connect Pulseaudio in to JACK

edit:
http://plugin.org.uk/ladspa-swh/docs/ladspa-swh.html
http://lsp-plug.in/
http://calf-studio-gear.org/