Tuning tubes to octave and twelfth partials produces a more pleasing tone

Evidence

The result is a fairly pure sinusoidal partial with weaker partials at higher frequency. The Javanese angklung uses three of these per note, the upper two tuned an octave and a twelfth above the lowest one, respectively, providing a more pleasing tone with significant strength in three partials, one for each tube. — Eric J. Heller, Why You Hear What You Hear- An…, 1909