The explanation about odd-harmonics being perceived as bad by humans is probably a lot simpler than Atmasphere's explanation. In the beginning, before electronics, the only harmonics that anything (except bagpipes, of course)could produce were even harmonics of its root vibration because that is the nature of vibrating bodies and sound and the nature of human hearing.
Old mechanical alarm clocks had to sound much more loudly than present electronic alarm clocks, because the old clocks produced a base tone with even harmonics due to its inherent vibrating nature, therefore the sound being more pleasing, while electronic alarm clocks produce (purposely) a base tone with odd harmonics (or dissonant chords), therefore the sound being more annoying, thus not needing to be as loud.
Salut, Bob P.
Old mechanical alarm clocks had to sound much more loudly than present electronic alarm clocks, because the old clocks produced a base tone with even harmonics due to its inherent vibrating nature, therefore the sound being more pleasing, while electronic alarm clocks produce (purposely) a base tone with odd harmonics (or dissonant chords), therefore the sound being more annoying, thus not needing to be as loud.
Salut, Bob P.