A system for auditory presentation of 3D scenes to the blind is presented, with the focus of the paper on the
synthesis of sound codes suitable to carry important scene information. First, a short review of existing
electronic travel aids for the blind (ETAs) is provided. Second, the project of the wearable ETA device, currently
under development at the Technical University of Lodz, is outlined, along with the system modules: 3D scene
reconstruction, object (obstacle) selection, synthesis of the sound code and the application of head related
transfer functions (HRTFs) for generating spatialized sound. The importance of psychoacoustics, especially
Bregman's theory of sound streams, is analyzed and proposed methods of sound code synthesis are presented,
along with the software used for their verification.