Small vibrating objects radiate weak sound because source size is far under one wavelength

Evidence

How big do the cells need to be? There is no single answer to this question, because a few smaller cells can often be replaced by one bigger cell, but there is a limit: the cells need to be much smaller than the shortest important sound wavelength, so that the information that they are being pushed on one side travels to the other sides in a time much shorter than a period of the sound. Usually a few centimeters or, at worst, a few millimeters on a side (giant on the scale of the distance between atoms and molecules in air) will suffice. — Eric J. Heller, Why You Hear What You Hear- An…, 96 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: A bare vibrating string is nearly inaudible without a soundboard; Air cells for sound simulation must be far smaller than the shortest wavelength — Eric J. Heller, Why You Hear What You Hear- An…, 96; Stringed instruments radiate low frequencies omnidirectionally but high frequencies directionally (+9 more)

Broader Connections

• Adjacent compression and rarefaction regions can short-circuit and kill radiated sound #expands (0.88)
• Air cells for sound simulation must be far smaller than the shortest wavelength #exemplifies (0.85) — Eric J. Heller, Why You Hear What You Hear- An…, 96
• Loud audible tones require only tiny surface velocities of millimeters per second #exemplifies (0.82)
• Micro-earthquakes far too small to feel can produce loud audible booms #exemplifies (0.80) — Eric J. Heller, Why You Hear What You Hear- An…, 690
• Reflection and diffraction of sound both depend on object size relative to wavelength #expands (0.80)
• Stringed instruments radiate low frequencies omnidirectionally but high frequencies directionally #expands (0.72)
• Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound #qualifies (0.72)