In a fire alarm system, horns, strobes, speakers, and bells are examples of _____ appliances.

In a fire alarm system, horns, strobes, speakers, and bells are categorized as notification appliances because their primary function is to alert occupants of a building to a fire or other emergency situation. These devices are designed to provide clear and immediate audio or visual signals to ensure timely evacuation and response, which is crucial for safety.

Notification appliances can be categorized into different types based on their mode of alert (audible vs. visual) and their specific applications within the fire alarm system. The effective operation of these devices is vital in minimizing risks to life and property during emergencies by ensuring that everyone is informed of potential danger.

Other options refer to different categories: ancillary appliances might support other systems without being directly related to the main alerting function; analog devices pertain to a specific method of signal processing rather than focusing on the type of alert; and unnecessary appliances would imply they have no functional purpose, which does not apply to the critical nature of notification devices in emergency scenarios.