Skilled players can adapt their control parameters according to the response of the instrument they are playing. In the case of the flute, the lip and face position relative to the mouthpiece is the main adjustment used for a fine control of the pitch, while the detailed geometry of the flute bore determines the intonation profile of the instrument along its tessiture. Using the negative bore concept, we apply controlled modifications of the intonation profile of the flute. Skilled players are then invited to play on different profiles of the same instrument while the geometrical and hydrodynamical control parameters are monitored.