What term describes a message emitted through loudspeakers or displayed on a computer screen as an alert?

The term that best describes a message emitted through loudspeakers or displayed on a computer screen as an alert is "Emergency notifications." This terminology encompasses a range of ways to communicate urgent information, whether through audiovisual means or visual displays. Emergency notifications are specifically designed to capture immediate attention and convey critical information in times of crisis, such as fire alarms, evacuation instructions, or other emergency updates.

Visual signals and textual signals could refer to alerts displayed visually, but they do not encompass the audio aspect. Audible alarms refer specifically to sound alerts and wouldn’t include notifications shown on screens. Therefore, "Emergency notifications" effectively describes the comprehensive nature of alerts aimed at ensuring safety and conveying important information swiftly and efficiently.