When you consider the strength of fluctuation, the most extreme one does not depend on the frequency and has constant strength. This is called "1/f0 Fluctuation". You will see that the wave strength is horizontal.

Like the figure below, the slope is leaning at 45 degrees and this is called "1/f Fluctuation".

Also, when the slope becomes steeper, it is called "1/f2 Fluctuation".

There is a characteristic in strength of fluctuation according to each music style. For instance, if you analyze classical music such as Mozart's tune, you will see that it has a fluctuation that is similar to "1/f1 Fluctuation". On the other hand, if you analyze heavier and louder music such as rock music, you will see that is has a fluctuation that is similar to "1/f2 Fluctuation".

The figures below show the result of analyzing the first and second movement of  Mozart's Concerto For Flute & Harp K.299. You can see that the slope is leaning at almost 45 degrees. You can download the analyzer from here, but please note that only Japanese version is currently available.

The figure below shows the result of analyzing the up-tempo tune of Motoharu's "Stardust Kids". You can see that the slope is steeper than that of above figures.

Although only two tunes are analyzed as examples, similar characteristic will be seen within the same music style. In addition, if you analyze a noise such as the left figure in the bottom, the result will be something like the right figure.

Roughly speaking, if you outline the slope of each music style, it will be something like the figure below.