Sound intensity measures energy transfer rate per unit area

Evidence

However, in general, we are more interested in the rate of energy transfer than in the total energy transferred. Therefore we are interested in the amount of energy transferred per unit of time, that is, the number of joules per second (watts) that propagate. Sound is also a three-dimensional quantity, and so a sound wave will occupy space. Because of this, it is helpful to characterize the rate of energy transfer with respect to area, that is, in terms of watts per unit area. This gives a quantity known as the “sound intensity,” which is a measure of the power density of a sound wave propagating in a particular direction, as shown in Figure 1.10. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 176

Categorization

• DEFINE: Defines sound intensity as power density (watts per unit area), distinct from total energy.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 176
• XREF: connects to: Sound intensity measures power density as watts per unit area — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 301; Sound power level can be derived by dividing intensity by radiating area; Sound pressure and intensity relate through air impedance of roughly 415 rayls (+1 more)

Broader Connections

• Sound intensity measures power density as watts per unit area #corroborates (1.00) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 301
• Sound power level can be derived by dividing intensity by radiating area #expands (0.75)
• Sound pressure and intensity relate through air impedance of roughly 415 rayls #expands (0.75)
• Inverse-square law governs direct sound intensity even inside enclosed spaces #expands (0.72)