Adjacent natural harmonics create smaller intervals as harmonic number increases.

Evidence

The development of harmony in Western music can be viewed in terms of the decreasing musical interval size between adjacent members of the natural harmonic series as the harmonic number is increased. Figure 3.3 shows the musical intervals between the first 10 harmonics of the natural harmonic series. The musical interval between adjacent harmonics must reduce as the harmonic number is increased since it is determined in terms of the f0 of the notes concerned by the ratio of the harmonic numbers themselves (e.g., 2:1 > 3:2 > 4:3 > 5:4 > 6:5 etc.). — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 932

Categorization

• DEFINE: Explains why harmonic intervals shrink — a core mechanism in psychoacoustics.
• XREF: Connects to the harmonic series content familiar from music theory and the overtone discussions in earlier chapters.