This study aims at evaluating the audibility of spectral modifications induced by slight but realistic changes in the headphone position over a listener's ears. Recordings have been performed on a dummy head on which 4 different headphone models were placed 8 times each. Musical excerpts and pink noise were played over the headphones and recorded with microphones located at the entrance of the blocked ear canal. These recordings were then presented to listeners over a single test headphone. The subjects had to assess the recordings in a 3I3AFC task to discriminate between the different headphone positions. The results indicate that, whatever the headphone model or the excerpt, the modifications caused by different positions were always perceived.