A cavity that vibrates at its own natural frequency and produces a sound that is louder than at other frequencies is demonstrating which of the following sound characteristics?

The correct choice is resonance. When a cavity vibrates at its own natural frequency, it amplifies sound waves that match this frequency, resulting in a significantly louder sound. This phenomenon occurs because the energy input from the sound waves aligns with the natural oscillation frequencies of the cavity, causing it to resonate. This amplification of sound at specific frequencies is a key characteristic of resonance.

In contrast, dissonance refers to a combination of sounds that create a sense of tension and instability rather than a clear enhancement of sound. Echo involves the reflection of sound waves, where a sound repeats after a delay, and timber refers to the unique quality or color of a sound that distinguishes it from others, irrespective of its loudness or pitch. Understanding these distinctions highlights the importance of resonance in producing compelling sound characteristics within a cavity.