What is a system called where the alarm signal is heard only in the immediate vicinity of the protected area?

A system where the alarm signal is heard only in the immediate vicinity of the protected area is referred to as a local alarm system. This type of alarm is designed to alert individuals in the surrounding area to potential threats or breaches without transmitting the signal to a remote monitoring station or a central alarm system. Local alarms are often used in residential settings or in smaller businesses, where immediate auditory alerts can prompt rapid response from those nearby.

Local alarm systems may include features such as sirens, bells, or other auditory signals that activate when a sensor is triggered. This immediate notification can be crucial for deterring potential intruders or alerting occupants of a fire or other emergency during the moments when rapid action is necessary.

The other options refer to different alarm configurations: proprietary systems are typically monitored and managed by the company that owns them, central alarm systems transmit alerts to a monitoring service, and portable alarm systems can be moved from one location to another but may not specifically be limited to the immediate vicinity only. These distinctions help clarify why the local alarm system is the correct answer in this context.