pulseeffects is a pretty neat tool for both playback and record effects including a compressor, gater, equalizer, filters, de-sser (can help quite a lot in reducing those sharp S sounds) and more. It has made a lot of presentations a lot more bearable for me, and my relatively low quality microphone in a noisy environment sound a lot better for others.

It only requires pulseaudio (almost all distro's already use it) and is available in most package repositories and as a flatpak.

https://github.com/wwmm/pulseeffects