On noise reduction of motorcycle helmets

Motorcycle helmets are mandatory on the safe driving, in spite of that the helmet usage rate decreases by the reason of discomfort. One of the most common complaints of the drivers is noise in the helmet. The noise may be structural bourne or air bourne. In this paper, measurements were performed to determine the external noise reduction of the motorcycle helmets, which is a preliminary study to improve the sound quality. The measurements were carried out on a specially designed field to provide a controlled acoustic environment. A Head & Torso simulator was used to measure noise in the built cabinet that produced by an omnidirectional sound source. The in-cab calibration was provided by in-house microphones. The excitation sounds were generated by using special software on the computer and the output was transmitted to the speaker cabinet via a sound card connected to an amplifier. Two types of motorcycle helmets were tested and the sound reduction results were compared.