Our review of scientific literature shows that the activity inside the clarinetist's vocal tract (VT) affects pitch and timbre, while also facilitating technical exercises. Clarinetists adapt their VT intuitively and, in some cases, may compensate an inadequate VT configuration through unnecessary pressure, resulting in technical blockage, fatigue, and impeding progress. The pedagogical literature sometimes disregards the explicit use of the VT, but common trends exist, using specific vowel formations to model VT configurations. To understand the actual approach of the VT in practice, we interviewed 12 renowned clarinetists from different continents. While all interviewees consider VT configurations important, some find VT manipulation an intuitively acquired skill. Most instructors use vowels to teach VT configurations. We propose a normalized system: /a/ for chalumeau, /?/ for throat register, /i/ for clarion, /ø/ for altissimo, /o/ as a base vowel, /?/-/i/ for ascending leaps, /i/-/?/ for descending intervals. We have applied this method to clarinet teaching at the conservatory with very encouraging results, as students easily understand the vowel system, and in relatively short time have achieved better sound quality and technical ease. Students have gained a conscious control of their VT and consequently have acquired a technique that they now use intuitively.