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Why do mics hear more echo than ears?
Old 25th February 2011
  #1
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Why do mics hear more echo than ears?

I've been placing microphones in the same spot where it sounds best to my ears, but the recording sounds so different from what expected—I think because it's capturing more room reverberation than my ears do.

Why is this?
Old 25th February 2011
  #2
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pearldrum944's Avatar
Hmm, not sure about the reverberation...but one issue is that the mic (most anyway) is mono placed in a single direction, not binaural stereo like you ears.

Don't just listen with your ears and place the mic, listen on headphones while you hone the placement to hear what you will actually be recording.

I use Vic Firth isolation headphones for this to block out as much "live" sound as possible.
Old 25th February 2011
  #3
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Yeah, reverberation is probably the wrong way to describe it. I suppose I'm trying to understand why the recording sounds more distant once it's recorded. It's like the brain filters that out or something.

Because of this, I've found it's really hard to capture live sound faithfully.

But I suppose that's what separates the good engineers from the bad.
Old 25th February 2011
  #4
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It's a brain thing. When you're in the room, you expect to hear the natural reverb/echo, so you don't really notice it as much.

Now, listen to that mic in a different room, you're brain is going to notice it much more because it's not natural to that room.

Dunno if that's the case, but it makes me sound all smart and ****e...
Old 25th February 2011
  #5
Registered User
Definitely a brain thing. Or in my world view, a Mind thing. (I separate Mind from the meat machine we call our brain).

IMO, our Mind is Separate from our Body, and can navigate seperately (not recommended) and will ultimately survive the death of our body. IMO, Mind communicates with Body - so our brain is merely a Modem to the Mind, not the CPU or Memory.

If we are talking to somebody who is moving around in a large reverberant space, the amount of wet sound varies a lot. But if we are listening to their words, we don't really register the wet sound so much, because our Mind is actively filtering out the information it deems less important. If you try to replicate this with super computers, it's mind boggling how much computational power you need to do this kind of trick. Which is exactly why you currently cannot purchase a plugin to remove reverb from vocals. But our Mind does this automatically and effortlessly.

IMO, the processing takes place in a higher dimension not restricted by 4D Time.
Old 25th February 2011
  #6
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E.rOk.stA's Avatar
 

While all the witty replies are nice it's actually more simple. You are boosting all the sounds in the room, not just your voice. Close mic'ing will give you less room 'verb while backing away from the mic will instantly reveal how good your room sounds.


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Old 25th February 2011
  #7
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Quote:
Originally Posted by lorkp View Post
I've been placing microphones in the same spot where it sounds best to my ears, but the recording sounds so different from what expected—I think because it's capturing more room reverberation than my ears do.

Why is this?
If you placed a dummy head binaural mike in that spot and listened back via good headphones, you would be astonished at how much it sounds like listening.

OTOH, if you compare either speaker or headphone playback of a single mono mike to the actual experience of listening in 3d with your ears, reverberation will sound totally different. In mono, there are no spatial cues to help your brain sort out direct from reflected sound, so the reverb shows up as more obvious, while actual listening gives you all those cues and helps you sort it out. This has been well known for many decades and is the reason why orchestra recordings done in mono back in the 50s were done in much drier halls than more recent stereo recordings, because we can deal with more reverb when we get the localization cues.

Cheers,

Otto
Old 25th February 2011
  #8
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mowmow's Avatar
I think that's because human can concentrate on what you want to hear, mic can't do that.

Also there might be some non linearity in the mic that softer sound become louder. Mic can have different output curves to both transient and even levels.
Old 25th February 2011
  #9
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That's really interesting about how recording halls changed once stereo systems and recording techniques became more common.

I feel like recording stereo makes things more straight forward. I wonder why it isn't more prevalent.

So if I started recording with stereo pairs, the result would be more natural sounding? And are there any disadvantages in the endproduct?
Old 25th February 2011
  #10
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Block one ear with a finger and listen in mono. What you hear and what the mic hears will match much better if you approach mic placement that way in a reverberant space.
Old 25th February 2011
  #11
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Quote:
Originally Posted by lorkp View Post
That's really interesting about how recording halls changed once stereo systems and recording techniques became more common.

I feel like recording stereo makes things more straight forward. I wonder why it isn't more prevalent.

So if I started recording with stereo pairs, the result would be more natural sounding? And are there any disadvantages in the endproduct?
The only disadvantage is the challenge of getting a good stereo recording - as far as I can tell, you need a good venue, good equipment, great musicians (who can balance their sound and get it down in a single take - no overdubs) and lots of time and patience to get it right. But it is more straightforward in the sense that it is more about the music and less about the technology. It goes woithout saying it is not suitable for all types of music. Leave Hip Hop, Techno, Rap, etc. in the studio. I love the sound of Chesky Records stuff - the way music was meant to sound!.
Old 25th February 2011
  #12
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I agree with the responses regarding the brain (or mind if you prefer) is helping filter out extraneous sounds allowing you to focus on the direct sound.

I read somwhere that a good rule of thumb is to move the mic 1/3 of the distance in toward the sound source from the point where it sounds good to the ear....or something like that. Someone please correct me if I'm off.
Old 25th February 2011
  #13
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Fletcher's Avatar
Wow - the power of the internet... lots of guesses and some of them actually close.

It is a brain thing [or mind... or selective control by an amazingly fast and intuitive "super computer"].

First - the ear [brain / mind] perceives reflected signals that reach the ear in under 19ms as part of the original signal which is interpreted as "comb filtering" in that original signal [this is part of what is known as the Haas effect]. Microphones just take it all in... what ever is exciting and moving the air in the room, the microphone will hear.

I don't know if anyone has the ability to try this at home or not... but next time you have a constant tone [say a tea kettle is going off]... notice that as you move your head from side to side the sound will often get louder and softer from just moving your head. Its not because the root of the sound is getting louder and softer, its because there are all kinds of short reflections from the room adding and subtracting from the original signal.

Now - as the brain [ear / mind] can differentiate between direct and reflected sounds [so long as they're over 19ms] the brain can turn down the reflections as they are perceived [to a point... its still pretty common that you have to turn and face the person you're talking to in hard reflective spaces like a train station].

The ear is selective in its perception... a microphone is not. It hears it all - turns what it hears from acoustic energy to electrical energy and spits it out at the other side. There is no interpretation in a microphone of any elements that live in the larger time domain [smaller time domain - yes, as in "phase response" stuff - which actually lives in the time domain albeit a very small time domain arguably caused by electronic components (like transformers and stuff like that) - but I digress].

Microphones - while wonderful bits of equipment and generally pretty stupid about what they will and will not hear... it takes smart people to put them in the right spot and position the source tone [musician?] and deal with the reflective character of the room as microphones will just turn acoustic energy into electrical pulses... sometimes [usually] adding a bit of their opinion through anomalies of their design [from the acoustic elements of the head basket to the electrical anomalies endemic to the pickup (transduction) element to the preparation of sending that signal on down to the microphone amplifier (output transformers / internal amplifiers / etc.)].

Sorry to be long winded - I figured it best to try and leave most of the "science" stuff out and try to explain this in a way [hopefully] most folks can understand.

If you have other questions about this stuff lemme know and I'll be happy to introduce you to some people that can probably help you a fair measure better than I can with the concepts.

Peace.
Old 25th February 2011
  #14
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E.rOk.stA's Avatar
 

Fletcher, you're a beast...


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Old 25th February 2011
  #15
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Why do PZM mics sound more like what you hear than most other mics?
Old 25th February 2011
  #16
Quote:
Originally Posted by Thumper View Post
It's a brain thing. When you're in the room, you expect to hear the natural reverb/echo, so you don't really notice it as much.

Now, listen to that mic in a different room, you're brain is going to notice it much more because it's not natural to that room.
Precisely
Old 25th February 2011
  #17
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santino9098i's Avatar
 

well first off PZM is a proprietary name for the line of Crown Boundary Microphones....or Pressure Zone Microphone

Putting a boundary mic up in alot like if part the wall in a room was a transducer and had an xlr output. If you just take the most used applications of boundary mics, their reasoning/usage pretty much describes itself.

Hockey games: Boundary Mics on the boards not just to pick up ice sounds, but also all the board's sounds in a certain area through the vibrations sent down the glass.

Tennis Match: Boundary mics at both ends placed on the ground picking up foot movement and giving a stereo image of both sides of the court.

These mics are usually always condenser mics as well so they are very sensitive and have a fairly good freq response.

The Half Cardioid pattern is what makes the boundary microphone be what it is...you could honestly make one yourself simply by affecting the polar pattern.

The Crown PZM actually has a small well...pressure zone that is made up of a small reflective plate with the tranducer pointing down at the base of the microphone...making it almost a polar pattern all its own.

I know there are many different models of the pzm by crown and there maybe some lacking with this post but its just a brain dump...first post!
Old 25th February 2011
  #18
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probably has something to do with the playback device being a playback device if you get what i mean, haha. obviosuly your ears are hearing in 3dimensions so the amount of reverb you hear naturally trhopugh your ears is spread amogst those dimensions and thats what your brain is used to de-coding.

obviously when you listen to a recording through how ever many monitors, the point of origin is fixed, when you hear naturally the points of origin for reverb are kinda of oinfinite depending on your surroundings.

sorry i dont explain myself very well, haha

didnt read the whole thread as im supposed to be working, im sure one of the technical guys has already provided a proper scientific explanation
Old 25th February 2011
  #19
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rjacobsen's Avatar
 

Great thread, some great info, thanks for sharing everyone!

rjacobsen
Old 25th February 2011
  #20
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vernier's Avatar
Digital recording alters the sound stage. Limiters and mic polar patterns do too, and can be used creatively to mess with whats going on in the back of the room.
.
.
Old 25th February 2011
  #21
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madtheory's Avatar
Can we just delete everything after Fletcher's post please, apart from the thanks..
Old 25th February 2011
  #22
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Quote:
Originally Posted by vernier View Post
Digital recording alters the sound stage.
[IMG]http://img9.imageshack.us/img9/2595/gradeabull****alerttran.jpg[/IMG]

///////

Fletcher is right about the echo-suppression effect (took a while for anyone to mention it) ... as are those who mentioned binaural vs mono ...
Old 25th February 2011
  #23
Registered User
Another viewpoint is that when we are listening to playback of a recording (whether mono or stereo or surround), we are often listening to the sound of one ambient space within another ambient space, if you will.

Our mind/brain wasn't originally designed to deal with decoding both.

It is all about multiple reflections - often extremely dense clusters of millions of reflections all at different distances/times. Artificial reverb tries to recreate this to some extend, but a natural space can create far more reflections than a powerful CPU.

Our brains learn from everything we have been exposed to - so now we have been exposed to decades of artificial reverbs, and we can train ourselves to hear the subtle differences between all types of reverb.

Our minds/brain can just do stuff in realtime that super computers can't do in weeks of rendering ...
Old 25th February 2011
  #24
Less is more

This is a great topic.

I think it's pretty simple really.

When you're standing in the room you hear a 3 dimensional ambience all around you which you tune out using your built-in sound-localization abilities that evolved as survival mechanisms.

When you mic and play back the sound you are forcing the entire experience through a single point (the mic's diaphragm) and then through speakers. There's no way this can give your senses enough information to tune out the ambience.

Ironically it is the fact that there is less ambient information that makes it seem like there is more.

I guess I am just rephrasing what has already been said, but trying to put it succinctly.

Carry on...



J~
Old 25th February 2011
  #25
Can be because your ears are direction and the mics used may be omni directional.
I dunno
Old 25th February 2011
  #26
Quote:
Originally Posted by CJ Mastering View Post
Can be because your ears are direction and the mics used may be omni directional.
I dunno

Our ears are omni. It is our noggin between them that makes us perceive stereo. That is the principle behind binaural sound.

J~
Old 26th February 2011
  #27
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ears are good

ears + cranial acoustic shadowing is awesome
Old 26th February 2011
  #28
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toneguru's Avatar
God I love you Fletcher.

I want to marry you Fletcher....

Not to me but to my sister. That way I can have you around at family functions and stuff.
Old 26th February 2011
  #29
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?

I'm not Fletcher-knocking ... but it's not rocket science guys ......

... and our ears are not strictly omni ... because of our eustachian tubes ... anyway, whatever :p
Old 26th February 2011
  #30
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Unclenny's Avatar
Quote:
Originally Posted by Kiwi View Post
IMO, our Mind is Separate from our Body, and can navigate seperately (not recommended) and will ultimately survive the death of our body.
This was a great thread from the start.

The way I see it......we play the music and we love the way it sounds. So we decide that we need to capture it for posterity....or maybe even profit. But, when captured by our microphones it never sounds quite like we played it.

So we mess with it, big time....to try to fool our brains, and those of our listeners, into believing that we are playing it live.

I wonder....how are we doing at that?
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