I teach courses related to the psychology of music, and this is one of the best applications of this sort that I have encountered. I use these sorts of programs to illustrate harmonics — what aspects of the spectrum change with different periodicity (pitch) and spectral shapes (timbres). It’s also fun to look at the running frequency content of music, especially music with vocals. STRENGTHS 1) very easy to use (unlike many other spectrogram programs where one must find the right parameters to effectively display music), 2) the display is beautiful, 3) it can play music files (I have only tried MP3) or use microphone input 4) there is a spectrum analyzer window that shows the spectrum at each moment. 5) it seems to run flawlessly, have not had a crash thus far 6) it tracks individual harmonics very well 7) one can speed up or slow down recorded music tracks (0.12x - 3x) 8) the 5kHz frequency cutoff for the spectrogram is appropriate for music visualization 9) piano keyboard mapped to spectrogram allows identification of particular note fundamental frequencies (F0s) for transcription purposes POSSIBLE IMPROVEMENTS 1) an oscilloscope window with triggering and time window parameters judiciously chosen for music (say a window of 50 ms duration) would be nice 2) the automatic gain control is great, but some sort of robust or adaptive scaling of the spectrogram gain would be desirable — one manually adjusts the gain to show the features one wants to visualize 3) It wasn’t clear what one or two of the controls do (labels might help) 4) I would also add a running short-time autocorrelation window (lags of 0-50 ms) to show pitch (F0)