Bear no harmonic relationship one to the other.
The resulting complex waveform may have many component frequencies, and there is no requirement that they all bear a harmonic relationship.
These events are not only unified by tempo, but also by their harmonic relationships.
Conversely, if notes are far apart their harmonic relationship is weakened and they loose their normal inter-relationship.
Whenever two or more notes are put together, a harmonic and therefore 'tonal' relationship is created, be it simple or complex.
In atonal music, the harmonic relationships may be very complex indeed, yet they are undoubtedly there.
For bassoons, the altissimo notes bear complicated harmonic relationships to the fundamental register.
They deny in their marriage any "implicative harmonic relationship."
As the two pitches approach a harmonic relationship, the frequency of beating decreases.
There is a harmonic relationship among the frequencies, and they are probably related to the size of the inner ear.