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outdoor interviews - levels/background noise

Discussion in 'Recording' started by madimg, Oct 19, 2011.

  1. madimg

    madimg Member

    Hi,

    I am a photographer, and I hate it when people ask say ''teach me a couple of important factors about taking photos, because im about to go and photograph a wedding for my friend''. It always makes me raise my hands to the sky.
    So on that note, I am about to do that here, so i apologise in advance.

    In my work, I have been asked to film some basic interviews outdoors. I have some level of university education in film and sound, but a shaky memory on it and to be honest, i didnt study it that long.

    The setup is a Røde shotgun mic and a lav (radio signal) and a canon XF100. Shotgun on top of camera and lav on the top button.

    Shot some tests the other day and had big levels problems, and im looking for some tips on this type of set-up. The lav itself seems to be picking up a LOT of ambient noise.

    Basically, both mics were set to around 20DB input, but the sound i got was mostly background noise. In this case it was trees rustling and cars passing by. even some ducks sounded like they were shouting! I have already gathered that i need a better wind shield. ok. But when i turn the volume of the shotgun off, the lav still picks up about 30DB of background noise. I guess I had the input level up high, and high sensitivity on the radio transmitter too, but I am worried to lose the voice of the subject. I can see that recording at a high sensitivity would effect the background noise, but i tested it on low as well and I didn't hear an improvement in what i captured.

    So.. how do i get a nice clean recording of the voice and the ambience, without them blending in this way through the one mic? How do i judge the correct mix of lav and shotgun?... is there a general rule of something like:
    lav hitting around 12-20DB
    shotgun hitting around 30-40DB?

    sorry for insulting your skill and experience levels! Any advice much appreciated!

    Mel
     
  2. dvdhawk

    dvdhawk Well-Known Member

    Hi and welcome to RO,

    I would give up on the lav. I don't believe you will ever be happy with the results you will get from a lavalier outdoors. They are extremely sensitive by design, and their omni-directional pattern make them effective for voice only when you can get them very close to the mouth of the person speaking. Those factors, plus the fact the person being mic'ed will be turning their head and changing the mic's ability to pick up their voice consistently makes for a frustrating combination. I don't even care for lavalier mics indoors, but that's another topic. Outdoors the slightest breeze will cause them to rumble very noticeably.

    You will be much better served by a handheld microphone that can be held within a few inches of the person speaking. A handheld cardioid dynamic mic such as a Shure SM58 should be readily accessible for you to experiment with. Even an omni-directional handheld like the Electro-Voice RE635 is still very typical for ENG and field interview use.

    The shotgun mic should be sufficient if the subject isn't too far away. (make sure you keep the back of the mic toward the worst source of background noise)

    Wind will always be an issue outdoors and moisture can / will ruin a condenser mic (most lavaliers) very quickly.

    Best of luck.
     
  3. RemyRAD

    RemyRAD Guest

    Here's another take. I used to work for NBC-TV for nearly 20 years. When you are outside, if the person speaking has the ability to hold a microphone, you really want to utilize an Omni-directional dynamic microphone like DVDhawk suggested such as the Electro-Voice 635. This is the microphone you see all of the newscasters using when they are at the beach, on location, during hurricanes. The newscasters & camera guys will die before the microphone does. And as mentioned, Permanently polarized condenser microphones are certainly problematic in high noise areas. But your person is supposed to wear that microphone, approximately 1 fist width below the base of their neck. On their Tie when possible or, on the left or right lapel if they are generally facing that way during an interview. Omnidirectional microphones typically suffer from less wind noise than any directional microphone made. And when utilizing a shotgun microphone outdoors, you generally need a superduper wind sock/dead cat, more than foam. A wireless lavalier is what most TV news reporters utilize.

    Then there is this other factor called "adjusting the volume properly". Most professional & semiprofessional camcorders feature XLR inputs along with phantom power for the microphones. They also frequently have some kind of switchable limiter available. These are certainly handy to use but there is a certain criteria in utilizing these. You must turn the limiter off first. With the limiter off, you adjust each microphone input level with your subject speaking at their loudest level they will be utilizing. Once you have adjusted the level so that it is 2/3 of the way up the meter, then you switch your limiter on. You don't turn on the limiter before that. Having the limiter on before you adjust your volume level generally allows you to increase background noise to the point of self-destruction of your brain. The limiter simply stops you from overblowing the recording while you can already be overblowing the volume level without adding any distortion. That's the problem you are hearing mostly. A standard directional dynamic microphone like the SM58 that was mentioned can be more effective at combating ambient noises. While at the same time, wind can be a greeter problem with those directional microphones. So if you are going to use one of those directional microphones, put a secondary foam condom on that bad boy. And you generally print with a shotgun microphone into one channel and the handheld or lavalier on the other channel since all digital camcorders are capable of 2-4 channels of recording. It's in your postproduction that you decide on whether they should be mixed or taken individually for your final product. And no, you don't put one in the left channel and the other in the right channel. That's just flat out wrong. One will be your main and one will be your backup or ambient track. So when you transfer your video into your computer, it will come out as a stereo pair. You must then separate the stereo pair into discrete left & right tracks. You then take your main talking head track and pan that to 12 o'clock, Mono. If you'd like to add a little noisy ambience, you would take your secondary track and also position that to 12 o'clock Mono. But that ambient track can also have some digital extremely short time decay reverb that will create something of a stereo ambient feel while having a strong Mono dialogue track. Just like the movies. And while outdoors, you'll probably want to utilize some high pass filter a.k.a. bass cut off from around 100 Hz on down. This will clean a lot of the dialogue up and reduce a lot of low-frequency rumble from engines and the wind. Many of us have utilized both the shotgun & the lavalier together and separately. For instance, in this lovely documentary of this singer-songwriter who was interviewed, the lavalier was used 90% of the time. Unfortunately, as she expounded on certain things during her interview, she would move her arms around quite a bit. This caused her necklace to keep rubbing against the lavalier making for terrible raucous clanking noises. So on those particular noisy instances, in the video editing software, I would have to quickly switch to the shotgun and back to the lavalier again. Because of the difference in sound between the two different kinds of microphones, I had to manipulate the equalization & include some downward expansion a.k.a. gating to keep the ambient noise level in check. While one can perceive the difference on some of these words it's certainly better than raucous clanking sounds. And that's why you have both a shotgun & lavalier. Get a microphone extension cord and put the lavalier on your talking head if possible.

    Another little thing that folks are doing today instead of dealing with these microphone issues, we now have a plethora of extremely miniature from solid-state memory chip recorders. You can take one of these and stick them in your talking heads pocket. Make sure you set it to 48 kHz, 24-bit, .wav not MP3 or WMA. Because these are all basically computer type devices, they can hold synchronization very accurately to each other with no external cables or intervention. Once recorded, it is simply transferred into the computer. Since the camcorder has its own soundtrack, it's simple to synchronize the wild soundtrack against the camcorder soundtrack. And in your postproduction, you would mute or extremely lower the level of the camcorder microphones in favor of the solid-state recorder soundtrack. This is where you can play some stereo ambient tricks such as the ability to hear certain sounds coming from other directions in the soundtrack i.e. cars passing from left to right or right to left, people walking by and saying things. Sounds of the city, street vendors, etc.. And that's what we do for documentary or feature film production.

    Remember switch off those limiters first before making level adjustments.
    Mx. Remy Ann David
     
  4. dvdhawk

    dvdhawk Well-Known Member

    As always Mx. Remy's advice is top-notch and based on her professional experience working with professional on-air talent. If you are not so fortunate to be working with pros, I'd push hard for the handheld.

    If you're reluctant to put a mic in their hands because it means moving around while dragging cables - I use a Sennheiser ew100 ENG system with a plug-in module that will make any mic wireless to the camera. As Remy says, along with the EV635, a combination you will often see on professional news broadcasts. The Sennheiser system also includes a lavalier and transmitter pack.

    I would also add that if you aren't, you should be monitoring the audio through headphones so you don't have any unpleasant surprises when you get back to the studio for the post-production.

    By the way, how do you like the Canon camera? Have you compared it to any others?
     

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