Reading: Room tone

Following on from issues with atmos sounds in my Assignment 3 moving image, I found an article on room tone by sound designer Woody Woodhall.

‘Room tone, sometimes called room noise or fill, is simply the recorded sound of a particular room that a scene is being shot in. That sound is caused by many factors – lights, refrigerators, air conditioning, people, furniture, as well as the “sound” of the microphone, the “sound” imparted by the recording device and the specifications of the recording’ (Woodhall, 2018).

No two rooms have the same room tone.

The main function of room tone is to cover unwanted noise and fill gaps in the sound.

A dialogue editor can fix problems with sound by adding a bit of room tone over the offending noises and adding a precise edit and some cross-fades.

If room tone has not been recorded, you have to create it from the audio clips you have:

  • take parts of the scene that are quiet
  • you can also find it in the handles of the audio clips – the longer the handles the better
  • put it all together and apply some noise reduction software to get rid of some of the issues
  • then double the length of your tone by copying it and reversing the second half

When editing location audio, besides creating a seamless dialogue track, the dialogue editor also creates a track that is called production effects (PFX) – any useful location recording that does not have dialogue in it (e.g. breaking a glass, knocking on a door, working in the kitchen, running water, chopping vegetables, etc.).

Editing the location PFX onto non-dialogue tracks helps create the final sound effects stems and sub-mixes.

Room tone is needed when PFX are removed or when bad lines are muted and replaced by ADR.

Room tone is also needed when you get busy noise in the middle of what should be silence. You can cut out the noise and replace it with room tone, if it matches.

Room tone can be used to keep the dialogue track filled with audio from start to finish, while other sounds might be happening in the sound track.

Room tone can be useful in allowing sound effects editors to enhance the PFX in the sound design and help blend foley recordings with the PFX and with the dialogue tracks for the final mixing.

‘Room tone is the glue in the sound editing that creates the continuity from edit to edit.’

Every room sounds differently according to its shape and contents, what machines are running, what traffic is passing outside, even what natural sounds can be heard such as birds. These things change throughout the day, so getting room tone at different times of the day can be useful.

Even one shot can have completely different tone than another shot in the same room, depending on what direction the mic is facing.

On-set room tone recordings are important because creating usable room tone from scraps of location recordings is difficult.

The most essential room tone to record is that in odd places.

Movies that are quiet or that have sparse music score and minimal sound effects leaves the dialogue track bare and audiences will be aware of this.

Room tone is an inevitable part of the filmmaking process.

30 seconds spent recording room tone on location can save dialogue editors hours in post production trying to create it.


Woodhall, W. (2018) ‘Room Tone – 28 Weeks of Post Audio Redux: #2 Do we really need it?’ On, July 02, 2018. At [Accessed on 10 November 2018]

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