What characteristic of sound defines a "dull" tonality in reeds?

A "dull" tonality in reeds is primarily characterized by the presence of lower partials. When those lower frequency components are more pronounced in the sound spectrum, the overall tonal quality becomes softer and less bright. This contributes to a rounded, mellow sound that we often associate with a dull tonality.

Rich harmonics, while they can also influence the overall tone, typically give a more vibrant and full character, which is not aligned with the concept of a dull sound. High frequencies generally contribute to brightness and clarity in tone, leading to a sharper sound rather than a dull one. Crescendo ability refers to the dynamic aspect of sound, related to how the volume can increase, but does not directly dictate the tonal quality of dullness.