OS X: Filter system audio-out to remove high-pitched noise?
- Set Soundflower as the default output device (in order to capture output from applications that don't support custom output devices)
- In the application that's used for the effects, set the input device to Soundflower and the output device to a normal output
The default output device can be changed from the Sound preference pane or Audio MIDI Setup:
The application that's used for the effects needs to support:
- Custom input and output devices (Fission doesn't?)
- Playthru with effects (Audacity doesn't?)
I added instructions for Garage Band and AU Lab, but any DAW or standalone version of an effect plugin would probably do as well.
Garage Band only allows you to make a new project by choosing a template. Anyway choose for example the Voice template:
Change the input and output devices in the preferences:
Focus an audio track, and enable playing back the input:
Add effects in the edit tab:
AU Lab was installed with Xcode before 4.3, but it can now be downloaded from https://developer.apple.com/downloads/.