Abstract
Accidents while reversing a vehicle is one of the main causes contributing to total number of accidents. There are few devices which can be installed to avoid these types of accidents. Reverse alarm is one of the most effective and an economic device which can be used to alert people and convey the intentions of a vehicle to reverse. In the meantime, this also creates annoyance to other community. In order to have an effective alerting sound system, it is required to study the difference in alerting and annoying wherein alerting is to the user who is behind a reversing vehicle and annoyance is the non-user who is representing the community. Hence it is required to have specifications for reverse alarms. Different type of reverse alarms namely tonal, multi tone and broad band were evaluated & compared based on various factors. To arrive at minimum required sound pressure level (SPL), road noise data was referred different times of a day and different locations in the city. Further to check directivity of reverse alarms, blindfold subjective experiment was conducted. A single valued annoyance index was arrived at by correlating the objective and subjective data from jury evaluation. For a reverse alarm to perform optimally it has to satisfy three factors i.e. less annoyance, SPL and directivity. Formulated a single valued Reverse Alarm Annoyance index (RAA) which is a function of different psychoacoustic metrics. It was observed that RAA is independent of SPL. It was observed that tonal noise fluctuates considerably more with distance and broadband alarm’s SPL reduces uniformly with distance. RAA can be used as a tool to evaluate any reverse alarm. This study concludes a suitable type of reverse alarm from India perspective which fulfills its functional requirements at the time be less annoying.