What is defined as the sound of an announcer speaker over footage?

The term that defines the sound of an announcer speaking over footage is known as a voice over. This technique is commonly used in various forms of media, such as films, television shows, documentaries, and advertisements, to convey information to the audience while visuals are presented on screen.

Voice overs serve multiple purposes, including providing narrative context, expressing character thoughts, and delivering commentary that enhances the story being told. They allow for a seamless connection between the auditory and visual elements, guiding the viewer's understanding of the content.

In contrast, dialogue refers to the spoken exchanges between characters, ambient sound encompasses the background noises that add realism to a scene, and sound effects are artificially created sounds added for dramatic effect. Each of these plays a unique role in audio production but does not specifically pertain to the concept of an announcer speaking over footage.