Over the last few years several electrocutaneous stimulation systems have been developed in our institute for conducting experiments intended to lead to the construction of technical aids for the deaf ("speech to skin"). All versions of these systems deliver current-controlled bipolar impulses to the skin. In the first part of our paper a short summary of the software and hardware components of the systems SEHR-1/ SEHR-2 and SEHR-3 will be given. In the second part an overview of general results of identification and discrimination tests will be presented. The third part describes a learning experiment that was conducted to compare experienced and inexperienced subjects.