Frequency stays constant across media, so slow speed shortens wavelength

Evidence

If you are sitting inside the lower medium, the wave crests arrive one after the other with the same period as in the medium above. (If a person above the surface of a pool is waving her arm once per second, the period will be one second whether you are looking from above or below the surface.) Because the wave is moving more slowly in the lower (blue) medium, the wavelength must be shorter to keep the frequency f the same. The rule is f = c1/λ1 = c2/λ2, where the c’s are the wave speeds and the λ’s are the wavelengths in the two media. — Eric J. Heller, Why You Hear What You Hear- An…, 181

Categorization

• DEFINE: Clarifies the frequency/speed/wavelength relation: frequency is conserved across media while wavelength adapts.
• corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 181
• XREF: connects to: Waves always refract toward regions of slower wave speed; Higher material density slows sound propagation speed

Broader Connections

• Higher material density slows sound propagation speed #qualifies (0.80)