In this study, we investigated the ability of blindfolded adults to discriminate between concave and convex auditory virtual surfaces. We used a Leap Motion device to measure the movements of the hand and fingers. Participants were asked to explore the space above the device with the palm of one hand and an auditory feed- back was produced only when the palm was moving into the boundaries of the surface. In order to demonstrate that curvature direction was correctly perceived by our participants, we estimated their discrimination thresholds with a psychophysical staircase procedure. Two groups of participants were fed with two different sonification of the surface. Results showed that most of the participants were able to learn the task. The best results were obtained with an auditory feedback related to the component of the hand velocity tangential to the virtual surface. This work proposes a contribution to the introduction in virtual reality of auditory virtual objects.