The Tai Dam, or “Black Tai” due to their traditional black clothing, are an ethnic minority with sizable communities in Thailand, Vietnam, Laos, China, France, and the United States, and khap is their main vocal genre used in both sacred and secular contexts. While studies have analyzed Tai Dam khap and music through the lens of preservation and identity (Chansri and Burusphat 2017), transmission and categorization (Lissoir 2016, 2015), instrumentation (Iamsin, Roongruang, and Nanthachak 2012), and social function (Jarusopon 2008), none have specifically focused on timbre. Based upon original fieldwork, I analyze the timbre of twenty-four secular Tai Dam khap documented from nine communities in Thailand, Vietnam, Laos, and the United States, focusing on the non-lexical vocable. Spectrograms are used to provide acoustic support for my timbral conclusions. I argue that the vocables in all twenty-four khap share a timbral concordance expressed through the bright [œ] vowel, as in the British English word “bird” or the French word “fleur”, which consistently delineates the larger sections and/or smaller phrases. In addition to the primary [œ] vowel, other secondary language sounds often appear such as the bright [I] and [i] vowels and the darker [ŋ] nasal. These are plotted against geography to reveal timbral correspondences between secondary khap language sounds and specific Tai Dam communities.