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Old January 24th, 2013, 11:49 AM   #1
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Proper Mic Placement

There seems to be a recurring question about how much a good mic placed on top your camera will improve your audio. The short answer is it will most likely improve it but it still will sound like crap. Here's a short video showing how much difference it can make.

Sanken CS-3e example - YouTube
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Old January 24th, 2013, 10:12 PM   #2
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Re: Proper Mic Placement

The on-camera mic in the video really had a lot of echo. And I mean, a LOT. Can't say that I ever remember getting that much. For just ordinary family videos and the like I use a Rode Stereo Video Mic on the hot shoe because it's easy and fast to set up. So far, I haven't noticed THAT much difference but maybe I've been lucky.

If there's any consolation, at least the audio from the on-board SVM is better than the built-in camera mic.

It would be interesting to hear what innovative solutions there are for one-man shows. Using a light stand with a boom that was posted earlier is a good idea. Lavaliers are an option. Hidden mic with a cable (but not practical for most family-type gatherings). At this point I'm running out of ideas.

Last edited by John Nantz; January 24th, 2013 at 10:13 PM. Reason: changed on-board camera mic to built-in camera mic
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Old January 24th, 2013, 11:54 PM   #3
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Re: Proper Mic Placement

That particular room was super live. Yes, it did have that much echo. No matter what mic you used on camera there would be that much echo. We actually had three cameras running and the other on camera mic had the same amount of echo.

For this interview we did boom in the mic on a light stand that had a boom arm. It allowed us to place it without having a shadow.
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Old January 25th, 2013, 12:09 AM   #4
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Re: Proper Mic Placement

For Round-Table discussions I've used this 25 puppy. I connect to an Senni TX and I can then "circle" the subjects, filming away. I don't know HOW it does it, mainly it's because it uses the table as a gathering and sound board, but the quality is quite acceptable indeed: Audio-Technica - Products - Microphones by Application - Fixed Installation - ATR4697

Sometimes "simple" does work. It also underlines that old rule: Get the mic as near to the audio source as is visually possible.

Grazie
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Old January 25th, 2013, 02:23 PM   #5
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Re: Proper Mic Placement

Yeah, the amount of echo depends on the room and mic placement most. After that, the off-axis performance of the mic will affect the characteristics of the recorded echo.

One tip is to get some stands and blankets and place them strategically. Last year, I did a recording in a very large room with large glass windows. It didn't sound all that live to the ear, but even with a well-placed hyper-cardioid mic, the echo was unfortunate. To this day, I wish I had hang a single blanket between the interviewee and the window. That simple, inexpensive fix would have changed the audio from not-bad to totally pro. And I wanted totally pro!

I've had stands and blankets on every shoot since!

Not long ago, friends shot some green screen video in a barn using a so-so shotgun. Though there were lots of items in the barn to break up echos, we were on a cement floor and the actor was facing the door. We put blankets under his feet and opened the door. (Brrr.) Fortunately, it wasn't windy and we were far from traffic. Echo problem solved. (And, yes, a Sanken CS-3e would have helped!)
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Old January 25th, 2013, 03:47 PM   #6
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Re: Proper Mic Placement

Interesting video, Garrett. Camera mounted mics should indeed be discouraged.

Of course, the video also illustrates the little publicised effects of using phantom powered condenser mics in close proximity to newly-washed hair.

Not quite as extreme as the other example below where a phantom supply of 48000V was accidentally supplied to the boom mic:
Attached Images
  

Last edited by Colin McDonald; January 25th, 2013 at 03:49 PM. Reason: ONLY KIDDING! Don't try that at home, folks - 48V is fine.
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Old January 26th, 2013, 12:29 AM   #7
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Re: Proper Mic Placement

I fully agree that proper mic placement is something that everybody needs to try.

As a wildlife filmmaker, I have decided to place my Sennheiser MKH 416 directly on the C300. I am able to get many useful sounds. Last month I was filming without the Sennheiser on my C300 and the desert fox came pretty close and started calling. And worse, my assistant thought that I am filming and recording sound, so didn't even move to pick up the microphone for fear of disturbing the fox which was directly staring at us and also for fearing that the onboard sound will get ruined. And then later both of us realised that we didn't record any sound. As humans, we mess up. So for certain situations, better to have some sound rather than nothing.

On another occasion, I was waiting for a leopard. Dawn was about to break in. Light was too low. A bird (Shikra) flew and sat on the branch over my head and started calling. I just pointed my camera up and recorded the sound. So I feel while one should place the microphones as closer to the subject, an on camera mic also helps, at least for my type of filming.
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Old January 26th, 2013, 02:37 AM   #8
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Re: Proper Mic Placement

Quote:
Originally Posted by Sabyasachi Patra View Post
I fully agree that proper mic placement is something that everybody needs to try.

As a wildlife filmmaker, I have decided to place my Sennheiser MKH 416 directly on the C300. I am able to get many useful sounds. Last month I was filming without the Sennheiser on my C300 and the desert fox came pretty close and started calling. And worse, my assistant thought that I am filming and recording sound, so didn't even move to pick up the microphone for fear of disturbing the fox which was directly staring at us and also for fearing that the onboard sound will get ruined. And then later both of us realised that we didn't record any sound. As humans, we mess up. So for certain situations, better to have some sound rather than nothing.

On another occasion, I was waiting for a leopard. Dawn was about to break in. Light was too low. A bird (Shikra) flew and sat on the branch over my head and started calling. I just pointed my camera up and recorded the sound. So I feel while one should place the microphones as closer to the subject, an on camera mic also helps, at least for my type of filming.
That is fine as a back-up but sadly you can not change the laws of physics so a mic placed on a camera 500 yards away will still sound like a mic 500 yards away, so to start off with just a camera mic mindset will end up giving you more un-useable sound than valid decent recordings that match the pictures.

Most of the sound on the BBC wildlife doco's is post produced with separate sound recordists working independent of the camera crew to get the sound they need, slapping a mic on the camera may get your something but it is still not the best way to do it!
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Old January 27th, 2013, 03:26 AM   #9
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Re: Proper Mic Placement

I completely agree with you. I prefer to get the sound recording while I am shooting, by directly recording to the camera as well as simultaneous separate sound recording. My onboard sound is helps to sync. I was talking about some rare situations which are not easily encountered by a separate sound recordist later. Ofcourse one an try FOLEY. Animals vocalise differently in different situations, and we simply don't have the understanding of that. In my case, the onboard mic serves as a record of understanding the behaviour. Most of the times when I am shooting very early in the morning or late in the evening, the ambient noise levels are pretty low and I am able to increase the gain without it sounding bad. I was just giving an alternate point of view as to why a microphone on top of a professional camera is not a sin. I am trying alternate ways of recording sound by remote placement of microphones. Some of the knowledge acquired from people here definitely helps.
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Old January 27th, 2013, 10:11 AM   #10
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Re: Proper Mic Placement

I know this is a video forum, but please - can we have some proper use of language here? How many people would refer to focus as zoom, or talk about pan when they mean zoom.

The clip you are listening to has NO ECHO WHATSOEVER!

The room is live because what you can hear is reverberation. The arrival at the microphone or ear of sound that has reflected from the various surfaces, creating arrival time differences. Until you can actually hear two or more repeats, it's reverb, not echo. It may seem a small point but echo and reverb are primary phenomena in audio and not being able to tell the difference is pretty bad. Up until recently, reverb was not able to be removed or reduced by software, but now it is - to a degree and subject to a bit of uncertainty.

The physics is so simple - camera mics give great general sound in mono or stereo, but if we look at distant sources of sound it's wanted v unwanted sound, and while narrower polar patterns help, distance reduction and narrower patterns win most times!

Please guys - can we just be accurate. Shouting hello at a mountain and hearing your own voice saying hello back, is echo. What you hear in a cavern or large cathedral is reverb.
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Old January 27th, 2013, 10:57 AM   #11
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Re: Proper Mic Placement

Echo is greater than 30 milliseconds.

Reverb is less than 30 milliseconds.

Echo is returned off of one or more distinct distant far away surfaces and don't necessarily create their own audio profile.

Reverb is returned from a multitude of surfaces, close by and which impinge on each other and tend to create their own audio profile.

Our Brains DO NOT and can't adjust for Echo - ie we hear distinct separation/s.

Our Brains DO adjust for reverb - ie we don't hear distinct separations. But we CAN train ourselves to hear it.

Now, all of this may seem nitpicking, but when we are dealing with echo it often wont be the same as how we deal with reverb.

The only thing, IMO, one can say is that they both contain sound energy in the form of longitudinal waves, and when they hit a relatively hard surfaces a lot of their energy is not absorbed but is reflected back. And that's about as far one can observe as a convergence of similarity. Further away from this description they are very different critters.

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Old January 27th, 2013, 12:49 PM   #12
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Re: Proper Mic Placement

Quote:
Originally Posted by Sabyasachi Patra View Post
I completely agree with you. I prefer to get the sound recording while I am shooting, by directly recording to the camera as well as simultaneous separate sound recording. My onboard sound is helps to sync.
Same here. Not only for syncing but for backup insurance. There's nothing like a little bit of redundancy because "Stuff" happens.

Animal sounds are quite unique and can't easily be replicated in post. If something happened when recording and nothing was captured on the camera you could be totally out of luck.

Have you ever used a parabolic reflector to aid capturing audio? Except for the bulkiness aspect, it seems this would be good for wildlife sounds. It's not like one can put a lavalier on them.

Speaking of wildlife recordings, there was a great video (not great from a videographers standpoint, but great from a wildlife standpoint) of a dolphin that requested help from a diver to remove some wire or line from a fishing net that was wrapped around it's fin. The divers in the boat recognized the dolphin was trying to tell them something and finally figured out it was a call for help.

Editorial Comment:
This was not only a call to help a lone dolphin, but a call to help a species, the animal kingdom, and actually, the whole environment.

A local salmon stream fish count has gone from ~125 ten years ago down to 0 last year. A large shopping center was built at it's headwaters and runoff from the development goes into the stream. Most people are totally clueless about the environment, and that includes the Poulsbo City Planning Commission and the Poulsbo Council that approved it. Ten years: From a Salmon stream to a Dead stream.
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Old January 27th, 2013, 01:29 PM   #13
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Re: Proper Mic Placement

Quote:
Originally Posted by Paul R Johnson View Post
I know this is a video forum, but please - can we have some proper use of language here? How many people would refer to focus as zoom, or talk about pan when they mean zoom.

The clip you are listening to has NO ECHO WHATSOEVER!

The room is live because what you can hear is reverberation. The arrival at the microphone or ear of sound that has reflected from the various surfaces, creating arrival time differences. Until you can actually hear two or more repeats, it's reverb, not echo. It may seem a small point but echo and reverb are primary phenomena in audio and not being able to tell the difference is pretty bad. Up until recently, reverb was not able to be removed or reduced by software, but now it is - to a degree and subject to a bit of uncertainty.

The physics is so simple - camera mics give great general sound in mono or stereo, but if we look at distant sources of sound it's wanted v unwanted sound, and while narrower polar patterns help, distance reduction and narrower patterns win most times!

Please guys - can we just be accurate. Shouting hello at a mountain and hearing your own voice saying hello back, is echo. What you hear in a cavern or large cathedral is reverb.
Don't want to start an argument but Paul, you are incorrect. From a physics standpoint (yes I started my college life out as a general physicist), reverberation is a series of echoes closely spaced so that the brain perceives it as a continuation of the original sound source. This usually occurs when the first arrival of reflected energy less than .03 seconds (3 ms) after the initial instance. That works out to having the reflective surface approximately 16 ft (5m) from the source. Reverb is a phenomenon created by echoes.

What you are hearing the the clip are echoes that exhibit properties of reverb. Again, as you say it may seem nitpicking but if we are to be truly accurate you cannot have reverb without echoes. In terms of physics and how sound works, the properties are the same between echo and reverb. The things you have to analyze to determine the effects of them and how you'd handle them have to deal with how the energy from the sound waves interact with each other. In other words how the effects of constructive and destructive interference affect the energy reaching the ear or mic.
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Old January 27th, 2013, 06:05 PM   #14
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Re: Proper Mic Placement

I suppose it is a matter of degree? How much is needed to be corrected, and by what method. Maybe it is the latter that determines just what of the 2 examples dictates the how.

Cheers

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Old January 27th, 2013, 07:25 PM   #15
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Re: Proper Mic Placement

Quote:
Originally Posted by Garrett Low
reverberation is a series of echoes closely spaced so that the brain perceives it as a continuation of the original sound source
I would agree with that if you replace "...series of echoes" with "...series of reflections."

According to the Audio Cyclopedia (copyright 1959, 1969), which I consider to the the granddaddy of audio reference books, Section 2.79 states: "What is an echo? -- The repetition of a sound caused by reflection from a surface. To be an echo, the reflected sound must be 1/20 of a second or longer behind the original sound."

Also, the Audio Cyclopedia, in a lengthy Section 2.34, states (in part): "Reverberation is the persistence of sound within an enclosure after the original sound has ceased."

Everything seems clear so far: an echo is one distinct reflected sound delayed by at least 1/20 second; reverberation is persistence.

But then the Section 2.34 goes on to say: "Reverberation may also be considered as a series of multiple echoes, decreasing in intensity, so closely spaced in time as to merge into a single continuous sound and eventually be completely absorbed..." So even the Audio Cyclopedia appears to contradict itself! (Again, if you replace "... multiple echoes" with "... multiple reflections" then it's entirely clear and I personally agree with that definition.)

A different set of definitions comes from Audio Postproduction for Digital Video, copyright 2002 by Jay Rose. He says:

"Reverberation is the collection of thousands of random reflections that real-world spaces contribute to a sound..."

"Echo is a series of evenly spaced repeats that get softer and softer. It doesn't sound like natural reverb."

But Jay doesn't make the distinction about minimum spacing between repeats. Could they be 20ms apart? 10ms? 1ms?

Personally, I like Audio Cyclopedia's definition of echo, and Jay's definition of reverberation. And what we've been talking about in this thread are neither... they are "reflections" making the room sound very "live."

But this discussion could go on... and on... and on... and on... and on... and on.......

Last edited by Greg Miller; January 27th, 2013 at 08:58 PM.
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