10 most common audio mistakes in documentary filmmaking

1. Not getting mic close enough. If you audio isn’t good enough, it’s probably because the mic isn’t close enough. Are you trying to get by with an on-camera mic? Get the mic off the camera. Really. At a minimum that will mean using a radio lavaliere. And preferably a shotgun mic operated on a boom pole. Use the hand trick to find the ideal mic position, as follows:

Place your thumb in front of your mouth. Fully spread your fingers at a 45 degree angle. The tip of your little finger is where the boom mic should ideally be, about 6-8 inches away. Of course, it varies with the subject, and with the shot. Sometimes you just can’t get that close without risking getting the mic in the shot. You can get away with 1′ away, maybe even 16″ away. But if you’re regularly 2-3 feet away, background noise is going to color your audio big time. And you can’t remove that in post.

2. Hiding lav on subject produces distracting clothing rustle. I’ve worked with professional sound recordists who tell me hiding lavs is the most challenging part of their job. And it’s true: once you put a lav under clothing, you’re going to have issues. It takes a lot of trial and testing to get it dialed correctly. Sometimes, it’s just impossible. I generally use lav audio as backup, preferring the cleaner sound that comes from a boom mic. But for those times when you’re counting on a hidden lav to pay your bills, here’s how to hide a lavaliere mic.

3. Handling noise caused by changing hand position on boom or mic. OK, you’ve committed to using a boom pole. Your sound is so much better already! But watch out – a low rumble will be introduced to your recordings every time you reposition your hands on the pole. So once you roll sound, settle quickly into a position you can hold for the entire take. It doesn’t have to be like lifting weights. Follow these boom mic recording tips and your audience will thank you.

4. Distracting noise in background. The most common offenders here are refrigerators and HVAC systems. Remember that shotgun mics are directional – so point the mic away from the direction of the noise. Better yet, eliminate it entirely by turning the heat down or tripping the fridge circuit breaker (put your keys in the fridge so that you don’t accidentally leave without restoring power). That’s why getting the mic overhead on a boom pole works so well – because sound rarely comes from below. But even shifting the mic 45 degrees can make a huge difference. Listen carefully before the take begins to find the best mic angle. The more background noise, the closer the mic will need to be.

5. Room is echoey (too “bright”). Small rooms are usually worse than large rooms, and any uncarpeted room with bare walls spells trouble. Basically, you want a room that is “homey”: carpeted, drapes on the windows, plush furniture, bookshelves lining the walls–anything that will break up sound waves. If you have a slight echo, however, it is now possible for you to fix it in post. Check out the Unveil plugin by Zynaptiq. It does magic to dampen slight reverb.

6. Forgetting to record room tone. When your take is finished, the last step is to record what silence sounds like in that particular environment. If you forget, as I still sometimes do, it makes it difficult to edit the dialog. So make it a ritual, like the chant I breath to myself every time I leave the house: keys, phone, wallet. Every time you say “that’s a wrap,” first say “30 seconds of room tone, please.”

7. Audio levels become clipped because of sudden loud noise. You’re recording some dialog and your subject starts laughing. Or cheering. Or shouting. If you have a good mixer, the limiter can automatically catch brief outbursts like this. But if you’re using inexpensive recorders and can’t turn the recording level down fast enough, you’ll get clipped audio. But once the damage is done, is there any way to fix this in post? Yes, believe it or not, there is. Some of the cheering crowd scenes in my documentary Beyond Naked would have been unusable if not for iZotope RX, an incredible suite of repair tools. The iZotope Declipper can rescue even horribly distorted audio.

8. Forgetting to charge/replace the batteries. Yep, it still happens to me. On some inexpensive recorders such as the Zoom H4N, if the batteries die during a take, you will lose the entire recording. So as a way to prevent this from happening, as well as a way to stay more organized, I recommend rolling early and often. On a lengthy interview, for example, don’t just hit record and forget about it until it’s over. At strategic points such as between questions, stop and re-roll. Also, get into the habit of charging/changing the batteries immediately AFTER each shoot. That way, you’ll always be ready to go.

9. Radio interference from cell phones. Almost everyone is carrying a smart phone these days. They stay connected by sending radio bursts that can be audible by a sensitive mic. Before every recording session, pretend that you are the captain of a plane about to take off: ask everyone in the room to put their phones into airplane mode. Not only will this prevent radio interference, but it will prevent your take from being ruined the old fashioned way: when the ringer goes off.

10. Using cheap gear. The difference between a $200 mic and a $1,200 mic is pretty amazing. And since pretty much every video you make from here to eternity will have sound, it makes sense to invest in a quality mic and a recorder that has decent pre-amps. Thankfully, Moore’s Law doesn’t apply to sound gear the way it does to camera sensors. You could easily be using the same mic you buy today in 10 or 15 years. So don’t scrimp on sound.

26 thoughts on “10 most common audio mistakes in documentary filmmaking

  1. Steven Bradford

    All great tips! Some new ones I hadn’t heard before, such as the hand one to get mic spacing.
    To 8, I’d add– Most of the time, you’re only recording from one mic, but your camera or audio recorder can record two channels. Record to both channels, but turn the input level down by 3 or 6 db on the duplicate track, (or use the separate L/R level controls on your camera, if it has them, many cameras can route one input to both tracks.) Then if it suddenly gets loud, you’ll have this under recorded back up channel to switch to in editing.

    I sometimes call this the Steve Ballmer setting.

  2. Dan McComb

    Bob, Unveil is amazing. Because most location sound environments are less than perfect, I find myself using it just about all the time now, as a final step in sound sweetening. And their free trail lasts a long time, so you can try before you buy.

  3. devtank

    Tip 3, suede gloves! thin suede gloves can actually help reduce the sound of hands on a pole.
    Tips 6 and 7; Recording room-tone can work with Izotope to give it a ‘template’ of what you want to remove from a recording.

    1. Dan McComb

      Absolutely Joe, room tone is great for creating a noise print for use with iZotope Denoiser, and any other plugin that allows you to capture a noise print to clean up a recording.

  4. Andrey

    And what to do with the sound of clothes. From time to time especially in winter the sound of clothes always disturbs. And I have a mic close enough in a right position

    1. Dan McComb

      Nylon clothing is the worst. It’s going to make horrible clothing rustle. I start simple: ask the subject to wear something else! Natural fibers such as wool are much better. If that isn’t an option, it’s time to break out the boom pole. One thing you might consider: in winter, if they are wearing a hat, you might be able to find a spot under the brim where you can hide the mic, that will get it up away from the nylon clothing.

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  6. Mau Nicoli

    Hello Dan!

    I like this post very much and it is very helpful, I would like to translate it and re-post it into my Blog, my blog is for sound guys, from field recordist to musicians, sound designers for film etc… If you let mi do this I will be very happy, because like I said, it is a very helpful list and very interesting one too.

    Cheers Dan and keep making some noise filmaking! Haha!

    1. Dan McComb

      Hi Mau,
      Thank you for your comment. I’m glad you found it helpful. I would be honored for you to translate it and repost. Please included a link to the original post somewhere, that’s all I ask.

  7. Gillian

    Thanks for this! i kind of knew it but you have laid it out so perfectly here that it cannot be forgotten. I am printing a copy of this to keep with my kit.
    I wish I’d had this list before i shot my last film it would have made the sound editor’s life a lot more pleasant!

    1. Dan McComb

      Hi Gillian,
      Glad you’re finding it useful. I like your idea of printing out a copy to keep with the gear – maybe that way I wouldn’t forget to follow my own advice more often, heh heh.

  8. Pingback: 10 most common audio mistakes in documentary filmmaking | Dan McComb | Industry Happenings

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  10. Circa3

    This is a great list. Many points on this list are very common, but once we start rolling, we seem to forget. I too, will print out this list and keep it with my audio kit as a reference, until it becomes second nature.


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