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Filmmaking Basics part 4: Getting Better Audio

Getting good audio in noisy environments like bars, festivals, or even an untreated room can be challenging. Here are some tips to get good audio on the spot, saving you time trying to fix it later.

1. Set your audio levels manually

To get better audio, you'll want to maximize the so-called ‘signal-to-noise ratio’: you want the signal (a speaking voice for example) to be as loud as possible (without clipping), and any background noise or hiss to be inaudible.

Leaving your audio levels on 'auto' means that your camera will raise the levels whenever there's a silence, which increases the background noise. This is why the first (an arguably most important) step in getting better audio, is to manually set the audio levels. Before recording, run a little mic test with your subject. For a speaking voice, the levels should fall around the -10dB/-12dB mark, and for concerts you might even want to drop the levels a little lower to avoid clipping. During recording, keep an eye on the levels or monitor your audio via headphones, because I can't count the number of times where a subject starts speaking louder and louder once they get into the flow ;-) Monitoring your audio will also help you track down interference from mobile phones or wifi interference in the case of wireless transmitters.

Not every camera allows you to view/hear/change the levels while recording. In those cases, it can be a good idea to set your levels a little lower just to be sure, or get an external recorder that allows you to record a 'safety track' at a slightly lower level.

2. Choose the right microphone

Different microphones have different characteristics and different pick-up patterns. Shotgun microphones are great at rejecting background noise because of their great directivity, but there are many scenarios where a shotgun isn’t the best option. Most shotguns don’t perform well indoors, and they often require a separate boom operator to get truly good results. In such cases a lavalier or reporter mic might be a better option.

While lavalier mics are a boon to one-man production crews, lavs often have an omnidirectional pickup pattern, making them a lot less useful in noisy environments. Omnidirectional mics (as the name suggests) pick up sound from every direction, so if you’re in a noisy environment or empty hall, that sound also gets picked up. For these demanding situations, a cardioid lav mic like the Sennheiser ME 4 can be a great solution. Cardioid mics are more directional than omnidirectional mics and have a tighter pickup pattern.

The same goes for reporter mics: while the most common ones like the Electrovoice RE-50, Sennheiser MD-42 and the Røde Reporter are omnidirectional, cardioid reporter mics like the Sennheiser MD-46 are much better at rejecting background noise. This comes at a cost though: cardioid reporter mics are more prone to wind- and handling-noise.

3. Move the microphone closer to your sound source

While many brands offer dedicated ‘on-camera’ microphones that conveniently slot into the hot-shoe on your camera, it’s the worst place for a microphone to be. To get better sound, your microphone should be as close to the sound source as it can get. No matter if you have a hyper-directional microphone, if it’s more than a few feet away from your subject, you will hear the room sound, voices will sound thin, and any background noise will likely get picked up.

If you have an on-camera mic like the Røde videomic or the Sennheiser MKE-400, get a mini-jack extension cable to move the microphone off camera and closer to your subject. It will instantly improve your audio.

Pocket 4K Monitor Not the best idea...

Of course, moving the microphone too close to the sound source can also be a bad idea, as you'll run into the risk of audio clipping or annoying 'pops' in your voice recordings. To avoid those popping-sounds, look into a pop-filter.

Moving the mic closer to your talent's mouth, not only makes the sound louder (rule of thumb: if you halve the distance to the mic, the sound gets 1/4 louder), but also emphasizes certain frequencies, especially the bass. You can use this effect to you advantage for those intimate voice-overs, but it can also lead to an audio track that is too boomy.

4. Point your microphone upwards

If you have one of the aforementioned on-camera mics, a shotgun or any other directional mic, point it upwards when recording. Although shotguns are most commonly seen pointed downwards from a boom, this also increases your chances of picking up clothes rustling, fingers fumbling, and footsteps. Pointing your shotgun horizontally will increase your chances of picking up background noise. Pointing your shotgun towards the sky will give give you the cleanest sound, simply because there isn’t any sound coming from the sky. Unless your shooting under an airplane flight route, that is.

5. Improve the acoustics of the room

Recording indoors comes with its own challenges: room acoustics can be less than ideal, and electric appliances like a fridge or ventilator can cause a disturbing hum in your final audio. We're often so used to these sounds, that our brain shuts them off. But they are there, and will often be picked up by the mic. Close your eyes and listen to any sounds/noises you hear in the room. Clap your hands to hear if there are any unwanted echoes. Check to see if the floor is made of reflective material like stone, or if sound bounces off the walls.

If a location is noisy, look for a room with better acoustics, or try to improve the acoustics by laying down a rug on the floor, closing the curtains, or shielding the microphone from a noisy side of the room by with a pillow or pointing it the other direction. Small DIY solutions like these can go a long way in improving your final audio.

6. Audio post-processing

Although it's always best to get it right in-camera, sometimes you just can't control the surroundings, or maybe you've been handed a terribly recorded audio tape. If there's a lot of background-noise, the first thing to do is to look for a way of removing the noisy frequency. Most editing-software comes with sensible presets to remove noise, but it can sometimes pay-off to manually find the offending frequency range and remove it using a visual equalizer. If the sound is too soft or the sound levels vary too much, adding some light compression might do the trick.

If the talent was too close to the (unshielded) microphone, you might hear 'popping' noises in 'p' and 'b' sounds. A way to fix that manually is to add a short fade-out and fade-in over the annoying pop, so it becomes much less prevalent.

If all else fails...

If you’ve tried all of the above, but still the inevitable happens and your set gets audio-bombed by a man in a Zorro suit, be sure to film it and include it in your edit. Viewers will at least understand what the noise comes from, and more easily be able to filter out the sound.

Cover image by Christian Wiediger on Unsplash