2.5 Sound

If I were to pick one area of film production where student or amateur film makers are likely to have problems it would be with the sound. The average film is an audio/visual production and both the sound and the picture are equally important. However, because the sound is usually being recorded by one person, and he or she is the only one who can hear what is being recorded, a film maker can very easily end up in the editing process with sound that is unusable. Therefore, if you have somebody recording sound in your crew, unless he or she is a professional, don’t hesitate to ask if you can listen through the headphones to an example of the sound they are recording. When you are listening to sound in this way you should close your eyes and concentrate on what you are hearing. The human brain is very good at blocking out sounds. As you are reading this, try stopping for a moment, closing your eyes and trying to identify all of the individual sounds you can hear. If you are reading it on a computer, for example, then it will most likely be making a sound that you were  probably not consciously aware of. All of these sounds, however, become very clear when you are listening to them in your film.

Getting the environment right

Bear these points in mind when recording sound on set:

  1. Florescent lights often have a buzzing sound. Turn them off and use other lighting
  2. Printers, photocopiers, computers, central heating, refrigerators and air conditioning units are all potential sound problems. Turn them off if possible.
  3. Windows are often opened on set between shots because the lights can make the room very warm. Make sure these are shut again before filming.
  4. Make sure that everybody in any adjoining areas are aware that you are filming and ask them to stay quiet while you are doing so.
  5. If you move your hand on the boom pole or cable it will often cause a distortion sound on the recording. Let the boom person listen through the headphones while moving a hand on the boom pole so that they understand the necessity of keeping still.

Dealing with sound problems

If there is a sound on the set that you cannot get rid of – such as passing traffic outside the window – there are two things you can do to minimize the sound problem it causes. Firstly, ensure that you are using a directional microphone and that your boom operator is positioned in such away that the microphone is between the sound you are recording and the sound that is causing the problem. In this way the microphone (mic) is aimed at the sound it wants and away from the sound it doesn’t and the directional qualities will minimize capture of disruptive sound.

The second thing you can do is have your camera operator open the scene by focusing on the source of the unwanted noise. If there is, for example, the noise of a ceiling fan throughout a scene, the audience will be distracted by the unidentified sound. If the scene starts with a shot of the ceiling fan making the noise and then tilts down into the action the problem is solved.

Sound levels

The sound levels on a camera (or recording device) are simply a volume control. However, if set too high the sound will distort and be unusable. There is usually a sound level gauge that shows if the sound is going higher than the safe level (peaking). Most cameras have two sound level settings – auto and manual. Auto will ensure that the sound never peaks so that it distorts and will automatically increase the level if the sound is too low. This is where a problem arises with auto sound levels. In moments of silence in the scene the auto sound levels will raise themselves because the camera’s computer will judge the sound to be too low. The natural noise of the room increases, therefore, often causing a humming or hissing noise in your audio.

It is for this reason that it is best to set manual sound levels. Get your actors to speak as loudly as they intend to in the scene and set your levels so that they do not peak. Some cameras record to more than one channel. If possible set the second channel a little bit lower than the first so that if one peaks the other may not. Remember, if you are using manual sound level you must check them before every scene as the actors in one scene may be louder or quieter than in the last.

Microphone choice

There are three main microphone options open to the sound engineer: the camera’s onboard mic, directional (rifle) mics or radio mics.

Onboard mic

This is normally a stereo microphone – recording to two channels, left and right. The sound quality of most onboard mics is quite acceptable. The difficulty is that, for good audio, the microphone needs to be close to the source of the sound. If the microphone is stuck onto the camera this means that the camera has to be close to the source of the sound. This, of course, is very limiting when it comes to choosing your shots. A good safety practice, where the camera allows it, is to use the onboard mic as an audio back-up to your directional or radio microphone.

Directional (rifle) mics

These are generally the microphones of choice on the film set. Fixed to the end of a boom pole, they can be placed very close to the sound source and, because they pick up sound mainly from the direction that they are pointed in, they minimize unwanted sound interference coming from elsewhere on the set.

Radio mics

These are very useful when filming such shots as figures talking while they walk down a street where it is difficult to get a microphone on a boom pole near while remaining out of the shot. A tiny microphone on a cable, plugged into a battery-powered transmitter, is hidden on the person or near the sound source. It sends a signal to a radio receiver that is plugged into the audio input of the camera or sound recording unit. The microphone picks up the sound mainly from a limited area directly around it. One difficulty with radio mics, however, is that they are very sensitive and are prone to distortion if the wearer’s clothes accidentally rub against them. They can also be quite expensive.

Boom operation

Those who haven’t tried it may underestimate the task involved in being a boom operator. Firstly, the boom operator must get the microphone as close to the source of the sound as possible without letting the microphone be seen in the shot. This may be easy at first but as the scene continues the boom can start to feel very heavy indeed and, without the boom operator realizing it, the microphone can dip down into the shot. The way to avoid this is – before shooting - to lower the microphone down until the camera operator tells you it has entered the frame. Now raise it back up slightly so that it is no longer in the frame. Then pick a point directly behind and slightly below the microphone but above where you know the top of the camera operator’s frame starts – such as a spot on a wall. Throughout the scene keep an eye on this point. As long as your microphone stays above it you can be sure that it isn’t dropping into the shot.


The sound person should make sure to keep notes about what they have recorded. If the sound was good during a ‘take’ (each recording of a scene is called a ‘take’. “Take One” refers to the first ‘take’, “Take Two, the second etc.) they should note that. If there was a problem – for example somebody bumped into the microphone and caused an unwanted noise - they should say what the problem was and when it occurred. The editor will refer to these notes in the editing process. It is also important to let the director know about any sound issues after each take so that he or she can decide if they need to re-take the scene.

Safety on set

In most cases, the microphone is connected to the camera or sound recording unit by a cable. This, of course, represents a tripping hazard. Ensure that everybody on set is aware of the potential danger.

Written and Practical Assignment

Record the audio for your film to a good standard.

Make notes for each audio ‘take’.