Auditory and Biomechanical Performance Requirements for Motorcycle Helmets

Abstract

The purpose of this paper is to examine some of the problems presented by the wearing of a helmet in the sensing of information necessary for safe operation of a motorcycle. The paper is organized into three major areas. One area is concerned with a laboratory study of simulated motorcycle operation and the sensing of sirens and horns of motor vehicles at various distances for subjects wearing helmets and subjects who served as control that wore no helmets. The second study reported is a parallel to the laboratory study but it was conducted in an outdoor setting. The third area considered is a biomechanical analysis of the head and neck of a motorcyclist who sustains a blow to the head in an accident.

The independent variables investigated in the two studies of auditory sensing were the type of helmet worn, the type of auditory information being presented to the subject, and the direction from which the auditory signal was presented to the subject. A motorcycle helmet with a full face shield and one without a full face shield were compared with a control level of a subject wearing no helmet. A warning siren and a motor vehicle horn were the two types of auditory signals presented to the subjects. The four directions of presentation of the auditory signal were front, rear, left and right.

Both of these tests of the ability of the motorcyclist to detect the two auditory signals indicated that the helmet did significantly attenuate the signal and that the emergency vehicle siren or horn would have to be dangerously close to the cyclist before it could be heard as compared to the cyclist under the same conditions who was not wearing a helmet.

The alleged problem of motorcycle helmets producing injuries to the cervical spine in certain types of impact situations was analyzed from a biomechanical standpoint. Some helmet designs were found to be capable of producing an injury to the neck for certain crash configurations between the helmet and a solid object. Suggestions are presented for modification of helmet design to significantly reduce the injury potential of the helmet for this type of injury, while at the same time protect the head from other types of injury.