How does a dry cast respond to percussion?

A dry cast responds to percussion in a resonant manner. This is because when striking a dry cast, the material's solid and enclosed nature can reflect sound vibrations, producing a sound characteristic of resonance. Unlike soft or flat sounds that might be associated with more yielding or hollow structures, the rigidity and density of a dry cast create a distinct resonance, which healthcare providers can use to assess the integrity of the cast and the underlying structures.

The other options correspond to sounds produced in different contexts. For instance, a dull sound might indicate fluid or solid masses, whereas a flat sound usually represents areas with little air, such as solid organs. A soft sound might be heard over areas with fluid or soft tissue. However, when dealing specifically with a dry cast, the resonant quality of the sound it produces upon percussion is the most accurate response.