The special binaural sound episode of Doctor Who appears to have been a hit with fans.
Knock Knock features 3D sound for anyone wearing headphones.
The episode has been available to watch in 3D sound on BBC iPlayer for just over a week, and reaction from fans has been positive.
Watching the latest episode of Doctor Who with 3D binaural audio sound! Brilliant! https://t.co/LDpAg9k5At
— Ken Howard (@ken_howard1) May 7, 2017
#DoctorWho needs to have this 3D immersive sound every week! It's brilliant and making Knock Knock even scarier!
— jordan (@jicrombie) May 6, 2017
— Ben Can Tweet (@ben_can_draw) May 10, 2017
— Luke Tizzard (@luke_tizzard) May 7, 2017
The June issue of TVBEurope will have more about the special episode, including whether there are plans for more.