In the following example, two short melodies are played.  The two melodies are separated by a fairly large distance: three octaves.   Nevertheless the intervallic content in each is identical; that is, the interval separating each tone is the same for both melodies.  Each melody is separated by a brief silence.

In the following example, a short melodic fragment will be played beginning on two different tones.  Each fragment is approximately an octave apart.  Neverthless, as in the previous example, the intervals between each tone of the melody is precisely the same for both melodies.  Again, each of the two fragments will be separated by a short silence.

You may notice that the two melodies in PlayList3 sounded more similar than those of PlayList4, even though the two melodies are farther apart in the former.  This is because the two melodies of the first play list exhibit octave equivalence .  Octave equivalence is reflected by the fact that each of the two melodies have identical tone-name sequences: C-D-E-F-G-F. In the second example (PlayList4), there is no octave equivalence: each of the melodies have different tone-name sequences: C-D-E-F-G-F followd by Db-Eb-F-Gb-Ab-Gb.

You can go back and play each play list again, if you wish. An Aside