Mac Audio output remove high pitch / high frequency sounds I suffer from tinnitus and sometimes, in videos or video calls, there is a random high pitch noise which is really irritating for me. Also, in video calls some people talk really softly and some are really loud.
Is here an app which can act as a high pass filter for high pitch and frequency sounds?
I recommend Rouge Amoebas Audio Hijack.
What you are looking for is actually a low pass filter. Low frequencies should pass it, high frequencies should be attenuated.
Audio Hijack is a high-quality macOS audio tool, which offers not only audio manipulation via an equalizer, but also a dedicated low pass filter.

Start Audio Hijack, add a New Session and select the preset Sweeten. This is a pre-build audio enhancement workflow for all sounds that are played by your selected output device. Then select the category Build-in effects and drag the Low Pass Filter block into the audio processing chain. It should look like the screenshot i attached. You can easily customize the cutoff frequency with a slider.
As soon as you press the start button on the bottom left, the audio effects will be applied.
In case a plain old equalizer is sufficient for you, you can try the free eqMac App.