Voice overs are used to narrate, outlining what is advertised. it is often a woman's voice as their voice is deemed friendly, it's used to inform the audience.

The voiceover is used to pose questions, these questions will be answered in the documentary. They are used to engage the reader and make the trailer memorable.

The voiceover will be assertive and a true reflection of the documentary, it is used to persuade the audience to watch my documentary.

Trailers are often inclusive of persuasive language, and a lot of it. This includes in the script, repetition, triadic structures and superlatives.

Sometimes the narrator for the documentary is used for the trailer, this is to make the audience familiar with his/hers voice.

Audio snippets from the documentary are also used, this is to convey the relationship between the advert and documentary

Why?

The purpose of researching codes and conventions of a radio advert is to inform me for when I create my own documentary. It makes me able to challenge or follow conventions, make it suit my target audience and persuade them to watch the documentary. To follows these codes and conventions, it makes me able to create a successful radio trailer.