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Binaural recording, an art for which the time has arrived

 
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jonty



Joined: 23 May 2007
Posts: 44

PostPosted: Mon Jul 09, 2007 2:34 am    Post subject: Binaural recording, an art for which the time has arrived Reply with quote

With the advent of cheap, small digital recording devices, binaural recording has finally come of age.

I did this about twenty five years ago with a binaural microphone system I made myself and a Walkman type cassette that would record in stereo as well as play.

The essence of binaural recording is that you have two very small microphones which you put in your ears like earbud headphones. You then record the output of those microphones with a stereo recorder.

A well done binaural recording is amazing to listen to over a good pair of headphones. You can localize the sounds almost as well as you can at the original event. The bass player is off to the left, the drummer is front and center and the keyboardist is off to the right and so on. A binaural recording also plays back fairly well over regular stereo loudspeakers.

I had to make my own microphones with components I bought from Radio Shack and put together myself. Now with the internet, it's easy to find and purchase binaural microphones.

Some binaural mikes are designed to clip onto your glasses and with the cables they end up looking like one of those little lanyards some people put on their glasses to keep them from smashing on the ground if they fall off. Ideal for recording without attracting a lot of attention.

This link has a binaural recording you can download and listen to:

http://www.milwaukeesymphony.org/symphonystore/othermerchandise.asp

You can check out a range of binaural microphones here:

http://www.minidisc.org/homemade_mics.html

http://www.dacs-audio.com/Distribution/Soundman/soundman_main.htm

http://www.core-sound.com/mics/1.php

http://web.archive.org/web/20080212072449/http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA328025

If you have unlimited money to spend, check out the Neumann KU 100 binaural microphone system, only $7500.00 :

http://www.performanceaudio.com/cgi/product_view.cgi?products_id=002522

Enjoy!
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Caimancroco



Joined: 17 Mar 2007
Posts: 5

PostPosted: Fri Jul 20, 2007 9:54 am    Post subject: Reply with quote

Shocked
i have to admit it's quite hard to understand how that really works
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jonty



Joined: 23 May 2007
Posts: 44

PostPosted: Sun Jul 22, 2007 6:47 am    Post subject: Reply with quote

Caimancroco wrote:
Shocked
i have to admit it's quite hard to understand how that really works



Our ears use the phase relationships and timing differences in the arrival of sound waves to localize sounds. Binaural recording captures much of that information and then when it is reproduced over headphones our ears interpret those phase and timing differences as being present at the actual recording session.

Bob Carver, the founder of Phase Linear, developed a system called Sonic Holography back in the early 80's that had a somewhat similar effect over loudspeakers. I had a demonstration record of the process that was really quite remarkable to listen to over a properly set up stereo system. The listener and the two speakers were best positioned in an equilateral triange, such that the listener was located right between the two speakers and was as far away from each speaker as the speakers were from each other.

You can still find Carver Sonic Holography preamps on ebay and many of them sound quite good to this day.

Of course, today the process can be easily duplicated in software like Wavosaur with delay timing and filtering.
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Wavosaur Main Developer
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Joined: 30 Sep 2006
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PostPosted: Sun Jul 22, 2007 8:26 am    Post subject: Reply with quote

Is this a recording with 2 microphones?

If I placed 2 microphones with 20 cm of shift (likes ears) I think it is possible to have good 3D reprentation.
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jonty



Joined: 23 May 2007
Posts: 44

PostPosted: Wed Jul 25, 2007 2:24 am    Post subject: Reply with quote

Wavosaur Main Developer wrote:
Is this a recording with 2 microphones?

If I placed 2 microphones with 20 cm of shift (likes ears) I think it is possible to have good 3D reprentation.


The pinnae of the ears and the presence of the head significantly alter the arrival timing, phase, volume and frequency distribution of the incoming sound waves.

That is why the Neumann binaural recording system has not only an artificial head but artificial pinnae also.

Even the shoulders have a part in sound localization. To an extent, sound waves reflecting off the shoulders help the ears and brain determine the localization of sounds that are overhead.

Our sound localization faculties have evolved over millions of years when the ability to accurately determine the direction of a sound was a distinct survival advantage. Our neuropsychological systems are exquisitely sophisticated and successfully fooling them is a remarkably difficult chore.

I've been reading the evolutionary psychology mailing list for a number of years now and the extent to which our behaviors and abilities are shaped by millions of years of evolution is only now becoming apparent to me.

A crossed cardoid array of which you speak does quite a good job of making a recording to play back over loudspeakers but it is far from a true binaural recording.

The Dolby headphone dll which I pointed to in my other thread is the result of decades of research into human psychoacoustic faculties by one of the most knowledgeable and well funded research teams in the world.

I'm approaching sixty and Dolby has been almost a household word since I was a young adult. Dolby B was introduced in cassette recorders when I was in my early twenties I think.

I have a cassette recorder that has Dolby B, Dolby C and Dolby HX Pro, all of which contribute considerably to the quality of analog recording systems. Dolby A was used for many years in professional recording studios.

Dolby Labs got a royalty from every tape deck sold with their systems incorporated into it and it was almost impossible to sell a deck without Dolby. They have vast financial resources and attract some of the best researchers in the world.
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Nikos



Joined: 31 Oct 2007
Posts: 46

PostPosted: Mon Nov 26, 2007 9:56 pm    Post subject: Reply with quote

I 'd rather have 4 ears positioned around my head. Then I could understand exactly where the sound is comming from.
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serious-minded Cool
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