In the following example you will hear two chromatic scales separated by exactly two octaves.  A chromatic scale is comprised of a seqence of preceptually equidistant tones in which the octave is subdivided into 12 parts.  Each scale is separated by a brief silence.

The following example also plays two chromatic scales.   However, these two are separated by one octave plus a semitone.  Each scale is separated by a brief silence.

You will notice that in these two sets of sequences, it is more difficult to say in which of the two sequence, the individual melodies sound the same than it was in the last pair of melodic sequences. This is an interesting phenomenon which is revisited somewhat in the tonal paradoxes chapter.