Constant spectrum melody

Along a piece of music, the spectrum measured within a narrow time window varies with the melody and the possible effects of instruments.

Therefore, it may seem paradoxical that a constant spectrum can be perceived as a melody rather than a stamp.

The paradox[1] is that the ear is not an abstract spectrograph: it "calculates" the Fourier transform of the audio signal in a narrow time window, but the slower variations are seen as temporal evolution and not as pitch.

However, the example of paradoxical melody above contains no infrasound (i.e. pure tone of period slower than the time window).

The present spectrum is made of multiple frequencies beating together, resulting in a superimposition of various pitches fading in and out at different moments and pace, thus forming the melody.