A simulation environment is used for the perceptual evaluation of sound pickup and reproduction techniques in a teleconference context. A project, named "Spatialisateur", developed by Ircam and Espaces Nouveaux aims at synthesizing virtual room effects, controlling the acoustical quality and the localization aspects in real time. The prototype generates a localization effect by use of binaural reproduction techniques, for a single listener with headphones or a loudspeaker pair. Binaural synthesis relies on the use of head-related transfer functions (HRTF), which realize a listener-specific encoding of localization cues for any position of the sound source. Parametric modelling techniques are used in order to reduce the computational cost of the binaural filtering process. Psychoacoustical tests have been undertaken to validate this prototype by comparing, for various configurations, the localization judgements of subjects in actual stereophonic listening and in headphone simulation of the stereophonic reproduction