CSND

ChromaSOUND is a general-purpose audio DSP program, that provides the following features :
- SSB "denoise", for reducing static on SSB signals
- Automatic notch filter, for removing tones, heterodynes, and those pesky carriers
- Bandpass, Low-Pass, High-Pass, and Band-stop (manual notch) filters
- User-defined filters, using the built-in Graphical Filter Designer.

Just drag your filter from the design window to an empty button!
- Selection of pre-defined filters,
- AGC, or Automatic Gain Control for operation under varying conditions