Which statement is not one of the three acoustic variables?

Which statement is not one of the three acoustic variables?

• A. Pressure
• B. Temperature
• C. Density
• D. Distance (particle motion)

Answer: (B)

In acoustics, a sound wave is described by three quantities that vary as the wave passes: pressure fluctuations, density fluctuations, and how far the particles move (distance or particle motion). Pressure changes drive the compressions and rarefactions; density changes accompany those compressions and rarefactions; distance (particle motion) describes the actual movement of particles as the wave propagates. Temperature, while it affects how fast sound travels and how the medium behaves, is not one of these fundamental acoustic variables. It’s a property of the medium, not a dynamic quantity that the wave itself describes. So temperature is the one that doesn’t belong among the three acoustic variables.

In acoustics, a sound wave is described by three quantities that vary as the wave passes: pressure fluctuations, density fluctuations, and how far the particles move (distance or particle motion). Pressure changes drive the compressions and rarefactions; density changes accompany those compressions and rarefactions; distance (particle motion) describes the actual movement of particles as the wave propagates. Temperature, while it affects how fast sound travels and how the medium behaves, is not one of these fundamental acoustic variables. It’s a property of the medium, not a dynamic quantity that the wave itself describes. So temperature is the one that doesn’t belong among the three acoustic variables.