Enhanced motorcycle safety through the development and evaluation of auditory alert system

• Motorcyclists are exposed to very high levels of background noise, especially during high-speed rides. • Warning messages on motorcycles are typically limited to visual displays; the use of sound for such purposes has been rather limited. • This study defines the framework and design constraints for a potential auditory alert system, considering factors such as ambient noise levels, helmet audio system characteristics, and psychoacoustics. • A design space in frequency and level was established, ensuring that warning tones remain audible even amid high in-helmet background noise levels. • A set of novel warning sounds for five directions and two urgency levels was created and evaluated for effectiveness as warning signals. Motorcyclists are often in dangerous situations in traffic. Timely warnings can be crucial in preventing accidents. Currently, warning messages are limited to dashboard displays, which may have potential inefficiencies as riders might not consistently check them, particularly in urgent situations demanding immediate response. While modern cars typically feature various auditory alert systems, such as open doors or parking sensors, the utilization of sound for such purposes in motorcycles has been rather limited. Hence, developing clear, easy-to-understand acoustic warning signals tailored for common warning scenarios becomes crucial for motorcyclist safety. This study defines the design constraints for a potential auditory alert system, considering factors like ambient noise and helmet audio system characteristics Afterwards, a set of warning tones, designed for five different directions and two different urgency cases, accommodating these limitations, was validated through psychoacoustical evaluations. All tested sounds adeptly alerted participants without causing elevated annoyance. Recognition times aligned with typical attentive driver reactions, with possible learning effects observed over repeated exposures. While a 100% correctness rate without situational context was not anticipated, directional correctness showed significant potential, emphasizing the importance of diverse design alternatives. Learning effects, particularly if widely adopted, could lead to instinctive reactions crucial in critical driving situations. At the end, the defined design space allows for the evaluation of different warning tones, promoting the exploration of optimal solutions for motorcyclist safety.