Audible warning devices are less effective in what type of traffic?

Audible warning devices, such as sirens and horns, are designed to alert other road users of the presence of an emergency vehicle. In heavy traffic, the effectiveness of these warning devices is significantly diminished. This occurs because loud ambient noises from numerous vehicles, engines, and general street sounds can mask or drown out the sound of the emergency vehicle's siren. Additionally, in a congested environment where vehicles are closely packed, it may be more challenging for drivers to hear the warning signals or react in a timely manner, as they are often focused on navigating their own immediate situation. The congestion can create a scenario where vehicles are unable to yield effectively, further reducing the utility of the audible alarms intended to clear a path. In contrast, in light or moderate traffic situations, drivers are more likely to hear and respond appropriately to sirens, as there are fewer competing sounds and vehicles to contend with.