Optimizing vocal efficiency by shifting the "laryngeal mechanism". Some factors, either socio-cultural or anatomical, genetic, or habitual, may orient our acoustical and phonatory expectations toward a specific "laryngeal mechanism" (referred to by Roubeau, Castellengo and Henrich). We prefer to keep the laryngeal mechanism we are used to even if our cultural environment or personal development offers us another one. Our vocal preferences may thus limit the modalities of professional exercise that we choose, and may confront us with compensatory symptomatology of vocal fatigue. Professional obligations or artistic choices may suggest to the consulting therapist a different orientation with respect to laryngeal mechanism whereby functional comfort and acoustical efficiency of ambitious vocal performances are optimized. We illustrate this with some clinical observations.