Many lawyers almost by rote ask the parties in an accident if they had the radio on at the time of the crash, but often whatever the answer there is little effective followup other than the inference that perhaps the driver wasn’t as attentive to the road because he was listening to music.
I’ve recently found a study that seems to suggest that listening to fast tempo music while driving consistently affects driving speed as well as speed estimates. The tempo of the background music also affects the frequency of traffic violations.
Music such as trance and house with beats of 120-140bpm were most associated with increased speed and virtual speed violations.
While the study itself was a virtual one, it hilites the need for further study in this underresearched area.