should include the testing of multiple siren systems and comparing them against one another. Sirens of interest are likely to include the traditional mechanical siren device, typically used by fire and rescue services, which is increasingly being replaced by the electronic siren used in this study; the second are low frequency siren devices, such as The Rumbler: Intersection Clearing System. Testing of these devices will aid in determining which sirens are more affected by the shadowing of vehicles so that appropriate recommendations can be made. The testing of different emergency vehicles is also important, as the different mounting locations and characteristics of the vehicles will affect the SPL. The second major focus of future work should be to further accurately represent the traffic scenarios examined in this study. The siren should be mounted in/on an actual emergency vehicle and the emergency vehicle should be moving. It is likely that the movement of the vehicle will alter the SPL at the driver’s seat. Finally, future experiments should be set in an actual traffic scenario, with multiple vehicles, idling (if at an intersection) or travelling (if on road). A more appropriate traffic setting, including traffic lights, light posts, medians, and buildings, which are all likely to affect the siren signal, should be employed. While this study does shed some light on the ‘shadow phenomenon’ it is clear that significant work is still required.