Most vehicles are now fitted with electronic sirens, which can produce a range of different sounds. Fire service driving training often includes the use of different sounds depending on traffic conditions and maneuver being performed. For instance, on a clear road, approaching a junction, the "wail" setting may be used, which gives a long up and down variation, with an unbroken tone, whereas, in heavy slow traffic, a "yelp" setting may be preferred, which is like a wail, but faster.