Choosing the right microphone when filming a conference will help you to deliver great video content, HD or 4K pictures need quality sound to match. Our first rule is ‘forget the on-board’ which refers to the built-in microphone of most professional cameras. On-board camera microphones are omni directional, meaning their recording pattern covers virtually everything in front of the camera, including all of the ambiance and likely any unwanted background noise. Using the on-board microphone to record a conference presenter is likely to result in a poor quality recording with vague and distant vocals. On-board microphones are generally designed for reference audio recording only.
If your conference venue has a PA system its worth investigating the possibility of taking a sound feed from it directly to the camera. Most systems will have a line-output that will give you a mix of all the microphones via one cable directly to your camera. Speak to the venue, see what is available and try to make use of any sound feed provision they may offer.
If you can’t get an audio feed from the venue you’ll need to make your own provision to get a good quality audio tracks recorded. Professional cameras/camcorders usually have two XLR audio inputs that are assignable as either internal microphone/line input or external microphone inputs. Using suitable, well placed external microphones will vastly improve the quality of your recordings, way beyond anything a cameras internal microphone will record.
To decide which microphones to use for conference recording its worth understanding the basic differences between three of the popular conference recording microphones.
Omni Directional Microphones
Omni-directional microphones capture overall sound from every direction, they won’t reject background noise or isolate a vocal from any ambiance. They can be useful for recording general audience or room atmos, applause etc. We occasionally use them for mic’ing an audience for question and answer sessions where it’s not possible to offer a hand-held radio microphone for the audience to pass round. Using an omni-directional microphone to cover an audience is sometimes a compromise, but can work quite well for smaller events.
Cardioid microphones capture sound mainly from the front, rejecting side and rear pick-up. Their front focus means they are a good choice for picking up dialogue from a conference top table or a panel of presenters on stage. Two cardioid microphones, one either side of a stage will deliver good overall coverage of conference presenters speaking from various positions.
Shotgun microphones have a very directional recording pattern designed for isolating vocals and rejecting unwanted sound to the sides and rear. We would usually use a good quality shotgun microphone to record the presenter at a conference lectern. The shotgun microphone is placed on a stand within approx 2m of the presenter (just out of shot if possible) with a long XLR cable ran back to the camera. Assuming the presenter stays at the lectern and doesn’t wander too far off axis, a shotgun microphone will record a strong lead audio track of the presenters vocal.
If you are filming a conference on more than one camera it’s worth utilising the additional audio inputs for extra microphones. Two cameras with the four microphone inputs will give you options to record both the presenters on stage and any audience participation. All four separate audio tracks can easily be brought together in the edit, turning on and off the individual audio tracks during the editing process will focus and fine tune the sound to whatever is happening on screen at a given point.
If you need more microphones than you have inputs, you might want to consider using an audio mixer connected to the camera, with it’s XLR input(s) switched to ‘Line’. This will enable you to set-up multiple microphones, connected to the camera by a single cable. But a word of caution! Unless you have a ‘sound engineer’ who’s responsibility it is during the event to mix the audio live, i.e. fade up/down each microphone as required, you will end up with all microphones live together, recorded as a single audio track. This will leave no control of the individual microphone levels during the editing process. Recording multiple microphones to camera as one mixed source can leave your content sounding like it has been recorded with the omin-directional on-board microphone, precisely what you were probably trying to avoid in the first place!