The codes and conventions of radio trailers are:
- They last for 30-40 seconds
- There is a sound bed used behind the main speaking in the advert
- There is an indirect link to the documentary- for example the idea of the documentry will be followed in the advert but it still keeps the adience wondering what the programme is about so that the audience is more intrigued to watch it.
- There is a summing up of the information at the end of the advert, which is usually the same voice as the voiceover in the documentary. This includes the title of the programme, the time that it will be shown and the channel that the programme is on.
- The advert includes clips from the documentary
- There are at least two different voices in the advert, one of which is the voiceover from the programme.
- Sometimes sound effects are used in the radio adverts
- The tone of the advert is usually informal although depending on the genre of the documentary, this can vary.
- The voices in the advert have clear pronunciation and a standard accent
- The target audience is adressed in the advert.
- The voiceover anchors the advert
- The voiceover includes the audience through the use of rhetorical questions
- The slogan of the documentary is said in the advert.