Several claims have been put forward to explain the character of Utah's card-cord merger, in which is variably produced as . Instances of words containing from the running speech of a Utahn who variably exhibits the merger were rated by a panel of speakers on whether they were produced as or , allowing utterances to be classified as merged (into ), unmerged, or intermediate. Merged and unmerged instances were not found to be separated cleanly when taking just F1 and F2 into consideration, but looking at F1, F2, and F3 simultaneously resulted in a clean split between those categories, with the intermediate cases falling along the border between them. Further, the formant values did not match up with any simple articulatory explanation for the merger and its attendant distinction. Not only does this demonstrate that Utah's card-cord merger is the result of the simultaneous manipulation of multiple articulatory features, it raises the possibility that clear separation between phonetic categories could be found in other cases that might generally be expected to have some overlap.