Cow is a waveform editor. It generates sounds out of graphs for amplitude and frequency. A handy graphical user interface (using Qt) helps you drawing these graphs.
The comprehensive C++ library MGEN for IC layout and connectivity comes with the X11/Motif full custom layout editor PARIS and the powerful waveform viewer/processor MANIAC. Industry proven, it is the basis for layout generators, placers, routers etc.
Sonogram and waveform display programm for Unix using different algorithms like FFT and LPC to display musical features or potential artefacts that you may no be able to hear. Superimposed tuneable Staff-Lines allow for easy transcription of music.