I have spoken about the importance of good audio for film. I recently had the privilege of helping shoot two short films with two different audio engineers. When I was in the edit bay, I noticed the audio was remarkable in one film and not always as good in the second. In scenes shot in small rooms, the audio had TONS of echoes. Nothing ruins a movie faster than bad audio.
Get Rid of Bad Audio Once and for All
The reason for the echoes is simple. The audio engineer with the echoey sound was using a shotgun mic (which I've discussed before). However, the audio engineer with the ever-clean audio utilized a hypercardio mic.
It would be best if you used the proper mic for the appropriate location.
Shotgun microphones (such as the Rode NTG-2) have a super or hyper-cardioid pickup pattern, which means they are very good at picking up sound in a narrow area directly in front of the microphone.
Shotgun microphones (on the other hand) do an outstanding job of picking up the sounds that are “off-axis” (sounds the mic is not pointed at). And if you look at a shotgun microphone, you'll see a series of vents along the edge of the mic – That help eliminate the off-axis sound.
(Incidentally, if you have an annoying sound on set when you're using a shotgun mic, pointing those vents toward the sound can help reduce the amount of unwanted sound.)
While shotgun microphones offer a lot of flexibility, they have a hard time in rooms with many sound-reflective surfaces. A shotgun microphone does not handle echo very well. This is because the same technology that helps eliminate off-axis sound has a hard time removing sound reflecting off hard surfaces.
This can lead to a very “hollow” or echoey sound in your recording. And while few instances of poor audio can be adjusted in post-production, echoes cannot be “fixed in post.”
So what do we do in such situations? You can try hanging sound-dampening materials around the area, but sometimes that is not an option.
This is when you might consider a microphone with a cardioid pickup pattern, such as the Rode NT3. Cardioid microphones do not have the “vents” along the side to eliminate off-axis sound, so they pick up sound in the broader area than shotguns, but they also don't have as much problem with echoes in a perfect reflective room.
This can save you a lot of headaches in the post and from having to rerecord your talent's dialogue in an ADR (Automatic Dialogue Replacement) session.
Like everything else in filmmaking, it is all about having the right tools for the right job. Sometimes a shotgun microphone is your best option, and you might need to switch to a cardioid mic. I always recommend testing out what you've got to see what works best in any given situation, and when in doubt, always roll a different take for audio.
Your editor and audience with thank you. And if you would like more tips like this, click here to grab your filmmaker checklist.
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Michael Head is a filmmaker and full-time geek living in the Dallas-Fort Worth Metro mess. Follow him at @michaeldhead. Check in every Tuesday for Micheal's “tech-Tuesday” articles. Check out his website at michaeldhead.wordpress.com.
