A Practical Guide to Field Recording Part 1

adapted from: Designing Sound: A Practical Guide to Field Recording, Part 1

Part 2 of A Practical Guide to Field Recording

Aaron Marks CC BY NC SA 3.0

Field recording is defined as any recording made outside of a controlled studio environment. So, pretty much any audio recording you make whether it’s in a garage, your backyard or out in the middle of nowhere is considered field recording. Recording inside a studio is already challenging enough, but add in portable equipment, wind noise, airplanes, birds and all of those unpredictable annoyances and you’ve got yourself a real challenge! 

The purposes of field recording

There is quite a variety of reasons for sending recordists and their gear into the ‘field’. Film and TV productions, newscasts, sound effects libraries, games and even music production all have dedicated professionals who’s task is to capture clean audio no matter what the situation. Working as a field recordist can put you in a wide range of situations and all with some definite challenges.

• As part of a film or TV production crew, the field recordist (also referred to as ‘sound recordist’ in this case) is not only expected to record actor dialog and specific sounds that may be happening in a scene, but to record ‘on location’ sounds for later sound design, location ambience and room tone for Automated Dialog Replacement (ADR).  Each of these tasks requires a specific thought process and sometimes different equipment to accomplish successfully.  As part of a location sound team, the variety of recording activity and the pace of the shooting schedule will keep you hopping.

• Live action news teams typically have a dedicated sound recordist who’s job is to make the on-air talent not only sound good but to record ‘story’ related sounds as well.  If the focus of the segment makes a sound, it’s a good idea to let the audience hear it.  These folks often find themselves in wildly unpredictable and uncontrolled situations as they chase down dramatic news stories.

• Sound effects libraries have to be recorded by someone and this is one instance where field recordists really get to show off their skills.  Recording everything from ambience to explosions, crickets to jet aircraft, there are plenty of noise making objects to be collected and cataloged, so there is plenty for these folks to do.  And knowing fellow sound designers will be listening very critically and using them in their work is a great motivator to get it right.  Plus having a viable and usable collection of sounds is a nice feather in your cap.

• Games require fresh sounds for practically every production.  Ambience and sound effects are the main focus of field recordists in this corner of the industry as they’re often found pointing microphones at typical subjects like weapons, exotic cars, military vehicles, aircraft, animals and junk yards.  These sounds are collected to be used ‘as is’ or as elements in the sound design creation process – so no sound is a bad sound.

• Music production is a little known venue for field recordist but one where they can play a major role in a performance.   For in-studio productions, ambience or sounds which help support the ‘story’ are often used, especially in the ambient genre, and non-musical sounds can be used as musical elements in beats or as percussion.  Recorded live music productions will typically require audience reactions as well as location related sound needs for television simulcast and future CD/DVD releases.

Field Microphones

Microphones come in all shapes and sizes and having the right one

pointed at the sound can make a huge difference.  The most expensive one isn’t always the best choice and the one that is perfect won’t always be practical. Field recording can often be a bit of compromise as you evaluate the conditions, sounds and equipment, the microphone you pick for any given situation can either solve prevalent issues or make them worse. Remember, sometimes microphones are chosen specifically for what they can’t hear rather than what they do.

Let’s face it, there are so many types of microphones to choose from that it becomes a real effort to find the right one for each situation. Most field recordists have their ‘go to’ mics, the ones they grab first whether it’s because they like the way it colors the sound or because they always have good luck with it. But, until your experience guides you, there are more scientific ways of choosing a useable mic for a given challenge.

Microphone types

There are basically two distinctions of microphones – ‘type’ and ‘polarity pattern’. ‘Type’ refers to the physical construction and characteristics of the mic, ‘polarity pattern’ describes how the microphone hears sound. Both have equal influence when deciding what is best for a given situation and should be given close consideration when making your choices.

Types

• **Stereo** These types of microphones are designed to capture a stereo image using a standard XY pattern, MS (mid/side) or matched pair configuration.  These are great for ambience and sound effects when required in stereo format.

• **Shotguns** From short shotguns to long, mono and stereo versions, these mics capture a narrow focused image of whatever sound it is pointed at and reject sound to the sides and rear.  These are perfect for recording dialog during a scene or any other sound that needs to be brought ‘closer’ or separated from other sounds.

• **General purpose** Utilitarian microphones which can be used in a wide variety of situations, these are great for general sound effects, voice and any other instances when a mono format is desired.

• **Lavalieres** These tiny microphones are designed specifically to capture voice in a variety of situations but their small size can be useful for other applications when the size of another mic is an issue.

• **Dynamic** These mics are generally robust, inexpensive, resistant to moisture and can handle sounds with heavy attacks, such as gunshots and snare drums with ease.  Their sensitivity doesn’t allow them to capture quiet sounds well but are great with loud sounds.

• **Condenser** Capable of capturing very quiet sounds, these powered microphones are perfect for whispers, quiet ambience and other sounds where their subtle nuances are desired.

• **Miscellaneous** In addition to the standard field microphones, other mics offer solutions to very specific needs.  Contact mics record the vibrations of an object and are not susceptible to issues ‘sound wave’ capturing mics do.  Hydrophones are specifically designed to record sounds in liquid.  Binaural microphones simulate how a person would hear a sound, typically a ‘head’ and microphones for ‘ears’.  Surround microphones have six mics placed in an array to capture sound from each direction for playback on a 5.1 system.

Polarity patterns

• **Omni-directional** The omni pattern has a equal response at all angles with a full 360 pickup angle. These mics have a very natural sound and are good if the room or space ambience is desirable.

Use omni-directional:

• Where the sound source to microphone distance is small so that the fact that it is non-directional does not cause a severe disadvantage.

• Where the source is a ‘talker’ and the mic can be very close, right in front of them.  This type is less susceptible to popping and no bass boost (proximity effect) from close use.

• When wind is a significant problem.  Pressure-sensitive microphones respond much less to wind noise than directional or velocity sensitive mics.

• Because of the requirement for a small size such as a lavaliere or planted mic.

• When multiple, spaced omni’s are used in one type of stereophonic recording – useful with certain large-scale effects such as a train moving past the array of mics.

• **Cardioids** The unidirectional pattern is most sensitive to sound arriving from the front of the mic and much less from the rear.  The most common type is the heart-shaped pattern and should be used if a more isolated pick-up is desired.

Use cardioids:

• When the sound field can be differentiated into desired sound coming from one direction and undesired sound from 180 degrees away such as placing a mic near a speaker on a busy street and pointing the mic at the talker and the back of the mic to the street.

• Note that cardioids, while the most common type of directional mic, are not widely used in film making (as in music recording or public address systems), hyper- and super-cardioids are used to discriminate against noise and reverberation in these cases.

• **Super/hyper-cardioids** Unidirectional mics come in other variations like the super-cardioid and hyper-cardioid.  These have a very focused pattern and are used when the source is far away or there is a lot of ambient noise to deal with.

Use hyper- and super-cardioids:

• When you want to discriminate against reverberation and have a mic with a relatively small size.

• Where the source of noise can be placed in the null zone between 110 to 126 degrees from the front and the desired source is on axis such as on a boom capturing an actor on-mic and placing the camera in the ‘null’ – typically with noisy film cameras.

• These considerations lead to the selection of these mics for boom use.

Use short shotguns:

• For greater discrimination against reverberation and noise at high frequencies although they are equal in bass and mid range frequencies.

• When, if the actor/event is moving, a boom operator can’t accurately aim the mic because of poor off-axis sound.

Use long shotguns:

• For the greatest discrimination against off-axis sound over a wider frequency range than the short shotgun.

• Outdoors, for wide shots, dolly shots and when the sound source is further away than normal.

• Indoor use is not generally recommended because the interaction of the complex polar pattern of this mic type with room acoustics leads to coloration.

Microphone selection factors

Unfortunately, it takes much more than simply picking a type and polarity pattern for the perfect mic to stand out – although it is a good start. How do you plan to mount the mic? What are conditions like on location? Are there any weather extremes which might be a concern? Answering appropriate questions which are specific to your mission will help you close in on the right equipment.

• Visible characteristics. The size of the microphone can impact the decision if it must be carried all day or if cramped space requires something small.  For example, large microphones are difficult to mount inside of an engine compartment when gathering vehicle sounds under driving scenarios – a lavaliere would make better sense than a long shotgun.  Additionally, the method of mounting the mic may be a factor if a shock mount, mic stand, blimp, boom pole or gaffers tape are used.

• The method the mic uses to change acoustic energy or ‘sound’ into electrical energy. There are advantages and disadvantages to using pressure or velocity sensitive mics, especially when wind noise is a factor. Contact mics are an entirely different sort of mic in this respect and are able to capture sounds from an interesting, non-sound wave perspective.

• Directional characteristics (polar pattern). Whether you intend to collect sounds from a full 360 degrees around the microphone or from a focused area, the polar pattern selection is not only chosen because of the direction of the wanted sound but often as a way to minimize unwanted sounds.

• Susceptibility to wind and handling noise. Wind is by far one of the biggest challenges of field recording and having a microphone which is able to ‘ignore’ its effects can sometimes save the day. Wind covers and other accessories can be effective but sometimes the right microphone makes all of the difference. Many field mics come with a ‘low cut/high pass’ feature as well which can minimize wind and handling noise.

• Coverage of the frequency spectrum without discrimination. Microphones are designed to be as generally flat in their frequency response as possible but due to their construction and circuitry will have bumps or dips in various spots along the spectrum. If the fundamental frequency you are recording is within the ‘flat’ portion of the mics frequency response, then you can expect no coloration unless that is what you’re looking for. Other interesting ‘features’, such as with some lavaliere microphones, have a bump in the higher frequencies to actually compensate for these mics hidden underneath an actor’s clothing.

• Coverage of the polar pattern across the frequencies. Unfortunately, frequency response isn’t always consistent throughout the entire polarity pattern of the mic. This isn’t so much a concern when using a shotgun mic, for example, but if the desired sound covers a wider area such as in ambience recordings, a better representation can be captured if the frequencies are constant throughout the entire pattern.

• Power requirements. If the microphone of choice requires power, this added condition will need a reliable source.  Some mics utilize internal batteries or can be powered from the recorder with phantom power, neither of which will impact a mobile setup other than restricting your choice of recorders.  Others that require a separate power supply might influence your ability to stay mobile. Ensure the power requirements don’t hamper your capabilities.

• Susceptibility to temperature and humidity. Extreme hot or cold conditions can not only affect the human equation but the gear as well. Batteries tend to become unreliable in cold conditions and equipment that usually runs hot increase the chance of damage or failure. Also, the overall sound and capabilities of a microphone, especially the delicate diaphragm when heated or cooled, can color the sound in ways that can make you cringe. If your location is going to be a challenge, research the equipment that can withstand the temperature and use it.

• Ability to handle loud and soft sounds. Recording sounds with a large dynamic range can test even the most experienced recordists. It’s challenging enough to record strictly loud or soft sounds on their own but when sessions are mixed, such as when recording gunshots and weapons Foley, microphones which can record both equally as well is a plus. Knowing what types of sounds you’re heading out into the field to record will ensure you take the mic that can handle both extremes when needed is a good thing.

• Ruggedness. Studio mics are typically more delicate due to their need to capture the smallest nuances of instruments and vocals, and that’s not to say you couldn’t take some nice large diaphragm condensers to the field if needed, but why bother if the mic can’t take the more demanding conditions? Ensure the mic selection is robust enough to handle the journey, being mounted to a vibrating, jostling vehicle, for example, and being knocked around by overly aggressive ninja recordists.

• And finally, how the mic sounds. Unfortunately, how the mic sounds can’t always be the first reason to choose one but it should weigh in as part of your decision. Some mics sound REALLY good no matter what you point them at and if they meet other criteria in your list, then these should be part of your arsenal. If you have several which are worthy, always choose the one which will capture your sounds the cleanest and in the highest quality because after all, you’re reputation and future employment possibilities are on the line.

More coming up! Part 2 will continue with recorder choices, field

recording accessories and recording techniques.

Adapted from Aaron Marks' A Practical Guide to Field Recording, Part 1 for Designing Sound.

CC BY NC SA 3.0

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