Often time, there's a song I really love except for a passage which sucks. Or, I love a passage but find it too short.
Is there a program that, almost without learning curve, allows to quickly and accurately cut and paste passages in a song? (I have Sound Forge but it's very difficult and time-consuming to maintain the exact rythm throughout multiple cuts and pastes)
There is no way to do it "without a learning curve". If you want a fairly easy program to use, other music producers I work with often recommend Audacity.
I don't use it, but in general, just get a better idea of how to highlight and zoom in and out in the program. If there's a section you want to hear or not hear again, pay close attention to where it starts and where it ends, to the millisecond. That would be where knowing how to zoom in helps.
Typically, a new "section" tends to start and/or end with a transient hit, such as (but not limited to) a cymbal or noise sweep. These also might have a kick drum embedded in the waveform. A cymbal waveform looks roughly like this:
while a kick drum waveform is usually much lower frequency and thus has a longer wavelength for its transient.
Or, you might hear the energy level change, the most obvious example being when the drums are all removed for a breakdown section. You'd see the removal of drums in many pop songs, for instance.
As an example, looking at this waveform (Call Me Maybe), you can correlate "break2" with a breakdown section where the strings and vocals dominate but there are no drums.
Other than that, it's up to you to train your ears to notice more precise timings, and learn how to zoom in and out and highlight precisely in audio editing software. See if you can correlate the waveform of that song with the song itself by watching the track marker moving horizontally as you hear the song.
