Adopt a style that is easy to listen to and unobtrusive
Viewers are not interested in the audio description itself. They just want the required information spoken to them in a way that is most easily understood and enjoyed. The description should therefore be recognisable as description rather than dialogue, but should not draw undue attention to itself in a way that makes it obtrusive.
Directions and techniques
Use present tense, active voice
Descriptions should generally use present tense and active voice. For example, “Malcolm opens the suitcase” rather than “Malcolm is opening the suitcase” or “The suitcase is opened by Malcolm”.
Use an appropriate tone of voice
Descriptions should be unobtrusive and neutral, but not lifeless or monotonous. Wherever possible, use human speakers rather than synthesized speech.
Make sure the describer’s voice is not similar to any speaker’s voice
The describer’s voice should be noticeably different from those of the speakers in the programme. This can be done by, for example, using a female describer for programmes with predominantly male voices or using a different accent, though not one that is radically alien to the intended audience.
Carefully control the volume of the programme audio and the description
The volume of the description should be constant.
The volume of the programme audio should be reduced, but not completely muted, while the description is being spoken and restored when the description ends. If a background noise such as traffic or laughter continues across three or four consecutive but closely spaced descriptions, the volume can be kept low throughout, rather than bursting in and out repeatedly.
If possible, music that has been quietened during a description should be reintroduced quickly but not instantly, to avoid a sudden burst of sound.