Something that lets me select a frequency above which all sounds would be filtered in real time? I don’t know if a software can separate the high pitched sounds from the rest of the sounds. If it was possible that would be perfect. If not just removing all sounds when any sound goes above the threshold.
EasyEffects is just a wonderful piece of audio software (given that you’re using pipewire as the audio backend). The filter plugin is probably the other notable option for this task.