Sound loses energy near walls because compression heat escapes and is not returned

Evidence

When air is compressed suddenly, it heats up and resists compression a little more than otherwise expected, just because it is warmer. When it is decompressed suddenly, it cools off. This fact eluded Sir Isaac Newton, and without it he failed to predict the speed of sound correctly, as we said in box 13.1. He died without understanding the source of his error. The heating owing to compression and cooling owing to rarefaction keeps happening once for each period if a sinusoidal tone is passing through open air. In open air, there is no net heat or energy loss because the heat has nowhere to go, since the air parcel is surrounded by more air doing the same thing. That changes radically if there is a solid or liquid surface nearby: the heat of compression is partially absorbed and conducted away; it is not all given back during the cooling part of the cycle. The sound wave suffers a loss of energy. — Eric J. Heller, Why You Hear What You Hear- An…, 1439

Categorization

• XREF: Connects to Newton’s failed speed-of-sound prediction, a classic explanatory thread about what sound is.
• CANDY: Newton never knowing why his sound-speed prediction was off makes a great bar fact.