All my blog posts about photography and video making are written for beginners with very rudimentary skills and inexpensive equipment. This post is no exception, but it deals with an audio issue which many home movie makers probably haven’t considered: room tone, or what might be called “the sound of silence.”
Really, what in the world is room tone? Well, it turns out that every space where you shoot video has a certain ambient sound which gets recorded when you shoot a clip there. Even if that place is very, very quiet there is still not absolute dead silence. If you shoot videos in two different but very quiet rooms, the sound of those clips may be discernably different! That’s because every space (in a certain time span) has its distinctive sound, depending in part on the objects in the room, even if those objects are not moving or making sounds of any kind. Following the filming of a scene, professional film makers always have all the actors and actresses freeze in place and then they record a video clip at least as long as the scene took, in order to record the room tone of that location. Why do they do that? Because when the sound track of the movie is being edited later, having a clip of what “silence” sounds like in that space is extremely important. If the sound editor needs to remove an unwanted sound from the dialogue track, say for instance the sound of a passing fire engine’s siren, he must have a way to hide the abruptness of the hole which is left when he erases the siren sound. That’s where the room tone comes in. He can use the room tone to fill in the dead silent gaps that are created when an unwanted sound is removed from the sound track. Some people put a long room tone clip on their timeline as a separate sound track. It doesn’t interfere with dialogue, because it’s virtually silent, but if an obtrusive sound is removed from the major track, the room tone track fills in the hole.
You don’t have to have a sound technician’s skill or sophisticated equipment to make use of room tone in your “home movies.” Here’s how to record room tone and how to use it in your editing phase (“post production”):
After you have filmed what you came to film, for instance, a person on the street whom you have interviewed, take equally as much time making another clip to record the ambient sound in that location. You don’t need special equipment for this. Use the same camera you used for the interview. Press the record button and keep recording for a good long time. Point the camera in the general direction that you had it before, but the visuals in this case don’t matter. You’re just interested in getting ambient sound.
Next, in a web browser, go to http://audio.online-convert.com/convert-to-mp3. Using that page you can turn the sound track of your room tone video clip into an MP3 file. Just click on the “choose file” button at the top of the page and navigate to where your room tone clip is. The title for that page is “Music Converter”, but trust me, if you upload your video file the program script of that page will strip the audio track away from the video, automatically. It takes just a moment. The page reports to you a link. When you click on that link it downloads the .mp3 tile to your computer. Bingo, you’ve got your room tone sound file, and you haven’t spent a penny on software to do it!
Now, once you have your room tone sound file, how do you use it? Well, if you’re lucky enough to have an earlier copy of Windows Movie Maker, the one designed for Windows Vista, you will have a timeline view in your editor. Treat that room tone file like a music file and place it on your timeline. However, if you’re running Windows 7, which doesn’t have a timeline version of Windows Movie Maker, I suggest you download another free movie editor, VideoSpin. This has a timeline view, plus some other editing tools which Windows Movie Maker doesn’t. (You will have to spend $14.99 for codecs to make VideoSpin work after a trial period, but that expense seems reasonable for this excellent, easy-to-use editor.)
So, in VideoSpin, lay down your room tone file on the extra sound track of the timeline. Let’s say that you have an unwanted sound in one of your video clips on the timeline which you want to remove. How do you do that? Split the slip where that unwanted sound begins, and again where it ends. Thus, you will have created a middle clip which contains just the portion of the audio you want to mute. Now, in that new small middle clip mute the sound completely by grabbing the sound level line and dragging it to the bottom on the right and left borders of the clip. Finally, click on the play button to review your edits. If you have followed these steps correctly you should have made the offensive sound disappear, but you won’t notice where it was removed, because the room tone track will fill in the audio hole.