Wiktionary
timbreless
a. Lacking timbre.
Usage examples of "timbreless".
But she heard, shimmering across hard, empty fields, the timbreless, haunting notes of the cyrillaya, tuned to the victory of the hunt withm the forests.
Indeed, Marion was a queer woman in all respects, from her broad face and squat body to her forced, timbreless voice and her unconvincing gestures.