Previous studies have only breached the subject of the shadowing effects that a vehicle can have in the effectiveness of an emergency siren. While it is a given that the presence of a barrier or obstruction will have some effect on the amount of sound attenuation, past research is limited. Most research is focused to acoustic barriers deigned for noise cancelation, such as troughs commonly used along highways and major roads. The Acoustics Australia Journal in 2011 briefly examined a study by Robinson and Casali, which concluded that low frequency signals, particularly those below 1000 Hz, are more effective at refracting around barriers. (Howard, Maddern, & Privopoulos, 2011) This study provides useful information for this work as the signals ability to bend around a blocking vehicle will play a pivotal role in the sound level that the listener perceives.