Professional ears not only require crystal-clear, high-resolution sound, but also protection from unexpected audio level peaks. Here's where the ActiveGard™ system built into Sennheiser's HD 300 PROtect headphone set steps in. Rather than just clipping audio peaks above 110 dB, the patented ActiveGard system actually trims down the overall sound level to the maximum permitted volume, while retaining all the information as well as dynamics in the process. Other design elements also protect the concentration of the user. Previously disruptive or harmful volumes therefore remain distortion-free and clear, as well as safe, plus production control is retained at all times. Not only does the HD 300 PROtect satisfy the European EC noise directive on industrial safety and noise control, but it also safeguards the hearing and presence of mind of all production staff, even in the event of big or small surprises.