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Filming a documentary alone : practical tips for a usable sound

Job description

A film, whatever from the web report to a feature film conveys a large part of its message through audio!
Even in a great silence (but always with a background sound) the sound brings a narrative dimension by expressing an atmosphere, a spirit, a state of mind ... often even the sound is used to deceive the look that is worn to the image, or on the contrary draw the eye to a specific purpose.
Just experience putting a News channel without being aware of the news (and without reading the banners) ... it's a safe bet that your interpretation of the image will be truncated, in all Incomplete case, even totally erroneous and against sense .... and yet the news channels are the first to neglect the sound quality.

Many documentaries produced in light means arrive with a sound quality totally deteriorated. Yet the theme treated, the narrative, the point of view of the director must be valued. But an insufficient audio quality quickly reduces the pretensions of the film's life all the more when film screenings and festivals are the targets.
Yet these are dramatic situations that I encounter more and more frequently in my activity.
Faced with budget arguments, it must be borne in mind that the budget economy carried on one side by depriving itself of technical and human resources for sound, will probably be much more expensive in the post-production step. And for a documentary it does not forgive.

So my first obvious advice when planning a documentary shoot is to plan and budget a sound operator and the gear needed for sound recording. Even for an intimate shoot, installed in time, the sound engineer is used to being discreet, responsive and find the right compromise between the visual and the sound field.

But let's stay realistic, projects are sometimes structured during production and start without any budget plan; in this case it would be necessary to be able to limit the damage by applying effective choices and techniques. Here are a few :


1) ALWAYS LISTEN on the headphones what you are recording: camera or recorder input monitoring.

This is common sense! A DOP will always watch the camera's monitoring during filming. A director too; it is very visual that attracts the eye. The same logic applies for sound. And yet ... do you still wear a headset to control the sound during a take? It's fundamental!

We must understand that our ears filter a lot in our daily lives. For example at the restaurant, you will focus on your guest or your plate which gives the illusion of hearing less loud surrounding noise ... it is your brain that will sort. A microphone does not know how to filter, all the discussions, all the noises will be captured at their real intensity. Only by listening to your capture through a headset will you realize it. Sometimes, even often to be fair, a sound environment that appears acceptable to the ear becomes much less so when listening through headphones.

Listening to the headphones also makes it easy to evaluate the settings made on the recorder or the camera. A sound too weak, too loud, saturated, background noise too high, interference .... everything appears much more obvious when listening to the headphones.

Moreover, it is not uncommon to see filmmakers with a headphones set listening a premix return made by the chief sound operator.... this is not a coincidence , the director has to guarantee the recorded material quality.

Casque pour prise de son.
Headphone Sennheiser HD25 so classic in filming



2) NEVER use a microphone facing the source.

The installation of microphones on the camera is a heresy !!! I still can not understand that these practices persist in camera manufacturers! ... Indeed the microphone is often installed perfectly parallel to the lens, ie there is a 90% chance that the microphone's camera is facing the sound source. This is the opposite of the logical and basic practice of sound recording!

To understand the reason is very simple: Sound is a vibration produced by air movement. The microphone is equipped with a capsule that reacts to this vibration; the more the air movement will be in front of the capsule, the more it will crash. This crush produces undesirable effects that can range from seemingly unnatural, with many acute, inconsistent bass, to saturations related to the crushing of the capsule.

The correct position of the microphone is located above and towards the sound source at an angle of 30 °. The closer the microphone is to the source, the more we will have a proximity effect (the desired source masking the surrounding noise), on the other hand the more the microphone will be distant and the surrounding noise will be present (this prevails for a resonance if the shooting is done in a closed place). In addition, the microphones are often studied to work with this inclination, and their frequencies response curve is calculated to compensate for this position.

There are small articulated arms (called magic arms) to attach the microphone to one end, and a clip on the camera at the other end. These articulated arms will already work the angulation, the distance to the source remaining as for it will be that of the camera. This is not the ideal but it corrects a first major flaw.

Bras magique
Articulated arm or magic arm


3) The good microphone choice adapted to the situation.

There are several microphones families. I'm not going to list them here, but I'm going to focus on a few notions that drive choice.
The first criterion to pay attention to is the powering of it. Indeed, the most sensitive microphones but also the most accurate are powered microphones, called electrostatic or condenser, which require a power "phantom" delivered by the preamplifier of the recorder (camera, or separate recorder). This 48V power supply needs to be activated. For recorders without phantom power, there are either small additional powerbox or mics powered by batteries. They are more rare (so less choice) but allow to overcome this lack. These static microphones offer more range and more sound definition.

The other technical category that differentiates microphones is directivity. There are a number of them, and those to be privileged are the super-cardioid, the hyper-cardioid or the shotgun ... they indicate their range, or more exactly their capacity to capture the sound coming from the source towards which they are pointed out by attenuating the sounds coming from the other directions (sides, back ...).

To summarize, a good static microphone (powered), super or hyper-cardioid or shotgun are suitable microphones for shooting.

Micro canon
Shotgun mic directivity


The microphones I am referring to can appear expensive and especially there is a very wide range. On this no secret, the more expensive they are, the higher quality is. But there are good compromises such as the Rode NTG-3 that I do not hesitate to recommend because it has a very interesting sound, a good directivity for a reasonable budget.



4) Protect the microphone from strong air movements.

As mentioned above, the microphones usually used in filming are very sensitive microphones. In outdoors sound recording it can present some problems (wind, movement ...). Turning microphones are often delivered with foam windscreens that should not be hesitated to install. These windscreens tend to alter the sound, but it's better than ending up with more or less violent noises in the sound. In windy conditions, they may be insufficient.
For more extreme situations and especially not to alter the sound, there are more expensive equipment that are perforated plastic shells preserving an air space around the microphone and especially more effective. These Windschield are sometimes mistakenly named Rycote (because this is a brand) and whose model must be adapted to the micro used.

Coque de protection microphone
Microphone protection shell: Windshield




5) Isolate the microphone from movements, shock and vibrations.

There again, due to the sensitivity of the microphone used, a simple installation of the microphone on a standard clamp can cause problems. Indeed the materials of the cameras or microphone stands are very conducive to the slightest vibration. The slightest handling noise can then take the proportions of a shock in the recorded sound. One way to significantly reduce these handling noises is to use a suspension. This allows the microphone to be installed on a flexible part thus damping most of the vibrations.

As for the protective shells, different models exist depending on the microphone itself, so be equipped with a compatible suspension.

Suspension de microphone
Microphone suspension




6)  Separate the microphone installation from the camera when the situation is appropriate.

As I mentioned at the beginning of this post, the distance and the angle between the camera and the sound source is not necessarily the ideal to achieve a good sound. As part of an indoor interview for example, it can be much more efficient and qualitative to install the microphone on a microphone stand and bring it closer to the most ready (not less than 12 inches) of the source ... of course avoiding to get into the frame and especially to pay attention to the shadows. This makes it possible to have a more appropriate distance for sound recording, to have the microphone mounted above the recorded source and to point at it with this famous 30° angle.

There are different models of different heights. It is necessary to favor a relatively heavy foot, with an articulated pole and allowing to rise above the height of man.


Microphone stand
Various models of microphone stands




7) The lapel microphone or the Lavalier.

The difference between the two is that one - the lapel microphone - attaches to a part of clothing and is often noticeable on the frame. As for the Lavalier micro is a much thinner microphone that is hidden behind the clothes, for some in the hair or directly stuck on the skin. The Lavalier is often of much better quality but much more expensive too.
These two types of microphones are often associated with an HF system and allows movement. However, they can not and must not be the only sound source. Indeed they have several disadvantages:

  • Their installation is often delicate (even for a lapel) and require a little preparation.
  • The HF link is another technical constraint that requires a little bit of technical knowledge indeed all frequencies are not usable in universal ways; they vary according to the places, the regions: the allowed frequency ranges are not the same according to the countries.
  • Lapel & Lavalier mics require specific connectivity depending on where they are going to be connected (HF system, recorder, camera ...)
  • The HF link produces a certain sound compression and therefore deteriorates its initial quality.
  • The Lavalier microphone or Lapel well installed produces a sound of proximity not all the time logical compared to the frame and the scenery.

To summarize the use of this type of microphones should not be the only source of sound. They make it possible to secure the catch in very specific conditions. It is often a mixture of the sound of the Lapel with the shotgun microphone which allows to restore natural sound in a complex sound environment situation.



8) The low cut filter is not to engage systematically, and be sure there is only one.

This is a vast subject that I will try to make very synthetic. On the microphones, but also on the recorders (more is the camera) there are filters to cut the low frequencies. It is very useful outside to reduce the deaf noise of traffic, movement, etc .... but this filter - though necessary - is not trivial. It deprives the sound of part of the sound spectrum. Where problems start is when all the low-cut filters are engaged and on the microphone, and on the recorder & often at different frequencies these "deteriorate" the sound which is then very depleted. The decision to engage the low cut should not be systematic, especially indoors and especially is evaluated after a sound environment listening in which the shooting takes place.



9) Emphasize an external audio recorder rather than lend complete confidence to the camera preamps.

We are now entering a more delicate part; we talked a lot about microphones but another part is fundamental as for the quality of the sound: it is that of the preamplifier now systematically available on cameras. The quality is very variable but to make things simple I assume that camera manufacturers put all their weapons in the quality of the image, very little in that of sound. It's even worse for cameras that act as a film camera.
A preamplifier of bad manufacture will quickly bring back the breath at moderate gain, and even if you do not hear it during the shooting this breath will appear at the sound post-production step.

Even if there is now effective software for the treatment of the breath, it must be understood that the sound zone (spectral) occupied by the breath is a sound zone where the natural sound of the source is not recorded; conclusion this alteration is irreversible.

I have sometimes advised directors (especially those equipped with "small" cameras or cameras) to leave with a dedicated audio recorder.
This implies more setting up, adjustments, monitoring but it is "the price to pay" in the face of the difficulty raised here.

In autonomous recorders there is a multitude of models, quality and obviously at very wide price ranges. There also no mystery remains, the higher the price, the higher the quality will be present. However, care must be taken that the microphone (s) used can be connected to it and that the efficiency of the preamplifier is sufficient; in other words, the two elements are in adequacy to produce a sound of their own.

Some directors have equipped themselves with small recorders such as those manufactured by Zoom, Tascam, or even Nagra now; these although very interesting to record sound environments are not necessarily adapted to catch verbal exchanges in proximity. By cons these recorders can be very good add-ons and an interesting accessory as it does not become your main audio recorder.



10) Optimize the recording level, avoid automatic adjustments.

Input or midrange audio recorders and cameras have automatic settings: Gain, auto gain, limiters .... even if I understand the ease and temptation they are to proscribe. Indeed, they often work in spite of the common sense because during a shoot there is a lot of variation of levels (dynamics) and these automatic adjustments adapt constantly producing falls of levels or lifts of breath which are very hardly unmanageable at the sound post-production step.

A good gain, is a gain adapted to the situation where the average level (as in the case of the speech) is a little above the half-way of the dynamic represented on the level bargraph ... On the other hand,  it must not clip the maximum level under penalty of hearing saturations occur ; this may be another type of problem at the time of audio post-production. It's really a game of balance and evaluation between the average level and the strongest level.

In any case, it is wrong to believe that because of the digital it is possible to record constantly at very low volume. Indeed, with a low gain, or very low, the decomposition of the sound signal into digital information will be of poor quality. The digital conversion will not have enough elements to reproduce a sound coherence.



11) Keep the same settings in the same place, the same scenery for the same sequence.

Changing the setting between each recording in the same scenery, even worse during recording, is a major mistake. This is all the more time lost during the sound post-production, because it will be necessary to compensate for these differences but also the same sound in the same context recorded at different earnings will not have the same sound range. These are mistakes that can sometimes be very difficult to catch up because not only volume related.

So the best advice here is that if you start recording with a setting, even if it's not optimal, you keep it until the end; the problem generated will be solved whatever happens at the moment of the sound post-production, so much as it is for the whole sequence which will guarantee a sound unit. The main thing to avoid is signal saturations.



12) Record the questions.

Regularly the questions asked are not planned to be kept at the film editing ... but the filming is also a part of unknown, improvisation and sometimes at the editing the questions prove to be necessary for the narration and the sense of the subject. It is a shame to deprive oneself of it. Equip the interviewer / journalist with a microphone or at worst have a small recorder nearby can recover these issues that otherwise appear with a sound disruption in the documentary.



13) Record separately the surround sound from the sets.

It is an element almost always neglected but so useful during the sound post-production work: record 1 to 2 minutes of sound of the shoot location! These ambiances have various utilities, they can often smooth sound environments changing during shooting, allow to make what are called "patches" when an unwanted sound event occurs during the take, and more generally to dress the sound editing with a mood bringing naturalness to the edited sequence.



14) Announce at the beginning of the recording purpose.

This is called "the announcement" ... it is essential when you capture the sound with a separate recorder. This makes it possible to identify the take, the scenery and the nature of this recorded sound. Also a clap facing camera (even with the hands) with audio recording helps a lot to synchronize the elements during editing especially when using separate recorders. It should not be overlooked is all the more time and headaches saved.



15) Back up frequently - listen to the recorded takes.

Everything is said in the title. The digital area does not decrease reliability, quite the opposite. But backing up is also starting to organize the elements that accumulate as filming and gain fluidity during post-production. The file has the enormous advantage of not being altered during its duplication. It must be used to secure his work. Listening to the sound taken out of the shooting context also makes it possible to evaluate the quality of the work produced, and especially to improve it.



16) Fit all sounds at the post-production editing step.

Last but not least, it is better too much material than not enough. All this cumulated material must be on the editing timeline before going into sound post-production.



Conclusion :

These are just technical bases that are suggested here. Maybe when you read these you say that yes the sound is complex, it really needs to be focused on ... and yet all I just mentioned is that small part of the work of the sound engineer / sound operator. But indeed it requires a great concentration as the material worked is abstract for the uninitiated or untrained. This is also why the sound is not worked to its proper need when a director is alone for the shoot ... the saving is then only postponed for a post-production time its much more important. Nevertheless for the productions and the directors who really have no choice, I hope that these few lines will help you in your creation.

If you want to ask me additional questions for a sound post-production of your film, do not hesitate to contact me thru the contact section.