The invention relates to a white film with a thickness in the range of 1 to 500 \u03bcm that contains a crystallizable thermoplast as the main component. A laminated intermediate layer is formed on a surface of the matrix from hard chromium, chromium nitride and titanium carbide in order, and a diamond-like carbon film is coated on an outer periphery of the intermediate layer. The cap is presintered to remove binder material at a low temperature. The synergetic training device is embodied in a dynamic technical device consisting of several soundproof booths which comprise training facilities and technical means using a sensor system.