What is a simplified loudspeaker that indicates the state of a system?

A simplified loudspeaker that indicates the state of a system could be a visual or auditory indicator representing the system's operational status. For instance, a colored LED that changes from green to red could signal normal operation versus an error state. Additionally, a basic buzzer might emit different tones to communicate various statuses, such as "ready," "processing," or "error." This approach allows for quick and intuitive understanding of the system's condition without complex displays.