For video producers who have limited experience in professional audio recording, choosing the right microphone in a given situation can often seem like a minefield. Not only do microphones come in a variety of shapes and sizes, they will also be grouped according to their physical build characteristics and pickup pattern.
Luckily, there are tried and tested methods when it comes to location recording that can make the decision-making process a lot easier. For most location recording applications, your decision will be based around different types of shotgun and lavalier microphones, each of which exhibit different recording characteristics.
Shotgun microphones, so named because their long narrow tube resembles the barrel of a shotgun, come in two common types: “long shotgun” and “short shotgun”. As a rule, a long shotgun will have a narrower angle of acceptance than a short shotgun – it will reject more off-axis sound from the side of the microphone. Short shotguns have a wider angle of acceptance and, as such, will pick up more off-axis sound and will not isolate the talent or sound source as well as a long shotgun will.
It is important to note that while shotgun mics are highly directional, they have small lobes of sensitivity to the left, right and rear and will therefore pick up sound from behind the microphone barrel. For this reason, shotgun mics are almost exclusively mounted on boom poles so that they can be directed at the talent from above, depending on framing, and this yields superior isolation of individual sources and reasonable separation from unwanted background noise.
Perhaps the greatest misunderstanding with regard to shotgun mics is that they are able to pick up sound from a greater distance than other types of microphone. While shotgun mics are extremely directional, the further they are from the source of the sound, the more likely they are to pick up unwanted ambient noise. It is the distance between the source and the mic that will have the most dramatic effect on recording quality regardless of the type, cost or quality of the mic.
Microphone Mounts and Booms
There comes a point in time when mounting a microphone on a camera becomes impractical and doesn’t allow the audio to be captured to its full potential. Moreover, any directional microphone will only capture predominantly in the direction that the camera is pointing, which inevitably makes a camera-mounted microphone a supplementary feature, for example, to capture guide audio.
Presuming that you are working as part of a production team as opposed to single-person shoots, it would seem nonsensical to spend money on a professional level microphone such as the Sennheiser MKH-416 or Neumann KMR 82i and then not spend the little extra on boom poles and suitable mounts for boom/handheld use. The most effective microphone mounting units utilise suspension systems that acoustically separate the microphone from hardware that is susceptible to transmission of sound waves or generating unwanted noise through movement. Any sound arriving at the microphone capsule will also arrive at any solid object such as a mount or camera and this sound wave will propagate through the medium causing unwanted vibration of that object. By using a suspension mount, these extraneous vibrations are minimised and the recorded sound is less likely to be influenced by external factors. It’s also true that when microphones are handheld, the opportunity for additional noise is at premium – even the slightest movement or accidental touch of the boom pole, especially when the mics are mobile, can transmit to the microphone and thus the recorded audio. In these situations, suspension mounts are invaluable in preserving the transparency and accuracy of your recorded audio.
Once you’ve selected your microphone and mount, and assuming you won’t be attaching it to the camera with a hot shoe adapter, you’ll need something to attach it to. To the casual observer, boom poles and hand grips are very much alike with little difference to choose from. For the majority of uses this is true, although there are options available depending on the intended use of the equipment. For example, extendable booms allow for greater flexibility of mic placement and enable the mic to follow the sound source more precisely. For extended scenes, balanced booms that use lightweight aluminium construction are particularly appreciated by the audio crew!
Windshields, Windsocks and The Duck
Recording outdoors in the UK can be a wonderful experience if you manage to schedule a shoot during the summer (for reference, this will last for about two days and can fall in any month between April and October). If you understandably miss the summer weather, it can generally be a bit windy. Or rainy. Normally, it will be both. Luckily, your audio doesn’t need to suffer because of prevailing weather.
One of the most useful tools to location recorders is the windshield, commonly known as a zeppelin due to the similarities in its appearance to… well, a zeppelin. Windshields will be used in conjunction with a boom pole or handheld mount and will be designed to fit over microphones of a certain length – although you could house a short shotgun mic in a windshield designed for a long shotgun mic, the best results are obtained when the windshield matches the specifications of the mic correctly. The primary function of the windshield is to filter out extraneous wind noise and air movement from indoor sources such as air conditioning units, but it is also tasked with protecting the microphone to some extent.
For challenging conditions, a windshield may need to be fitted with a windsock such as the Windjammer by Rycote. Windsocks are typically synthetic fur-covered sleeves that will be attached to a windshield using Velcro or a zip. While these are excellent for filtering out wind noise, it’s worth being aware that they will also filter out some high frequency content from your audio source before it reaches the microphone capsule. With this in mind, it’s important not to use a full windshield and windsock system all of the time, although some windsocks have been designed with a much shorter fur that consequently attenuates high frequencies to a lesser degree at the expense of protection from stronger winds. For static outside broadcasts, additional protection may be required to shield the microphone and windshield from rain. Rycote, for example, offer a waterproof roof for their Modular Windshield and S-Series system called The Duck. As well as protecting the mic and windsock, solutions such as The Duck also minimise rain noise and further improve the quality of the recorded audio.
As a compromise, many companies now offer intermediate systems like Rycote’s Softie Windshield. Instead of being a fully encapsulating enclosure for a microphone, these intermediate windshields slip over the capsule of the mic quickly and easily. This ease of setup along with the practicality of the smaller size of the unit allow them to be transported and put into action quickly and efficiently, making them particularly useful in news-gathering situations.
Wireless Systems and Lavalier Microphones
Despite wireless systems and lavalier microphones being inherently separate technologies, they are most commonly used together to provide a mobile and covert recording solution. With the exception of adding enhanced functionality to portable recorders like the M-Audio Microtrack (which we’ll look at shortly), lavalier mics – when used in combination with wireless transmitters and receivers – are excellent for spot-mic’ing and for maintaining constant and consistent close-proximity audio signals from talent. Lavalier microphones are particularly suited to this latter situation due to their small size, which enables them to be hidden within an actor’s clothing or in and around a set to accurately capture nuanced sound from a performance.
In my experience, the understanding of wireless systems is polarised between end users, some of whom understand the benefits and limitations while others understand that they require this technology to get a job done, but have little experience in its use and operation. The main question that comes up (largely, I suspect, as a result of budget constraints) is whether one receiver can accept the signal of more than one transmitter. The answer, unfortunately, is no. Well, strictly speaking you can, but the results will be largely unusable. With that said, there are a number of units available that include twin receivers and modular systems for multi-channel setups that also reduce the amount of rack space required for large systems.
Should you need to, however, the output of one transmitter can be received by multiple receivers. This means that the output from one transmitter can be sent to multiple receivers on multiple cameras for larger productions.
One thing worthy of mention is that wireless systems, even those operating in the less cluttered UHF range, are susceptible to interference. Wherever possible, wired audio connections are preferable to preserve signal fidelity, although the benefit of having wireless transmission of audio can often outweigh the slight degradation in audio quality. The location you record in will also have a bearing on the quality of the signal between the transmitter and receiver – on one occasion I remember arriving at a recording with a myriad of wireless systems only to find out that the proximity of the location to the local airport meant that we effectively ended up in a wireless ‘shadow’ due to the airport’s communication systems. In certain situations like this, having a wired backup is always a good idea!