Binaural is a method of sound reproduction that is intended to replicate the way the human brain understands sound to give the listener as natural an experience as possible. Rather than using a series of speakers to reproduce a soundscape, the Binaural process records sound using two microphones separated by the width of a human head. When listening to the replay through headphones, the effect is to replicate the sound going into each ear giving the listener the effect of actually being in the room where the sound was recorded.
The binaural edition of Knock Knock will be available on BBC iPlayer from 8.10pm on Saturday, 6 May.
The binaural process can be heard on the preview clip on the official BBC Doctor Who page. To experience it you need to listen to the clip on headphones.