Can somebody tell me more about Stereo Binaural Sound

[jckinnick]

I saw this while looking up info on Lou Reeds Street Hassle album.


"Recorded using a process known as Stereo Binaural Sound created by Manfred Schunke. An attempt to create a more "3D" style of soundstage, it has been stated that headphones are the preferential listening medium."

[ubertar]

Usually a dummy head is used, with an omni electret condenser in each ear of the head. But you can use your own head, whether or not you're a dummy. The tape op omnis work well for this. I posted some stuff I did a while back, but I must have deleted the file since then; it's not there. Anyway, dummy heads are expensive, but the TO omnis are cheap. Just don't sue me if they get stuck in your ears or you get an infection...

[jckinnick]

so its pretty much a surround sound effect

[Mark Alan Miller]

Well, it uses two channels to impart some directional cues. Where in a stereo (speaker) setup, sound from both channels reaches both ears, with a binaural recording, one listens on headphones, one channel per ear discretely. When binaural recordings are made (with the aforementioned dummy head technique) some of the directional cues we normally get through our own outer ears (pinnae) is captured, in albeit simplified form, witht he dummy head mics. On headphones, our brain gets to discern those cues, and we perceive some directionality. If I recall, 'The Final Cut' from Pink Floyd has some of this stuff on it too...

I'd love to hear your binaural recordings, Ubertar!

[vorian]

How different would this be from, say, running a Jecklin Disk with a pair of omnis? Or does it have to be shaped like a real human head?

[bap]

The Jecklin Disk can produce similar effect but is still expensive.

If you 'google' DIY Jecklyn Disc you can come up with how some have built their own. I made one out of 1/4 inch plexiglass and fake sheeps wool and have used it with STO-2s - kind of a fun thing to have around but I'm sure mine aren't as technologically perfect as the million dollar ones with big brains and great ears behind the development.

[Mark Alan Miller]

The Jecklin Disc will facilitate one of the cues that we use to localize sound ...well, two, I suppose...
The first is the time arrival difference between ears. Only sounds on the front-to-back plane will arrive at both ears at the same time.
The second is the slight diminishing of the upper frequencies in the further ear by the "shadow" of the "head".

In both cases a Jecklin Disc will be less effective than a dummy head as the size, mass, circumference, and so on are generally not the same as the average human head, as far as I know. Although one could surely be fashioned...

One important factor in "3D" binaural sound it the effect of the pinnae and the ear canal on the sound - in effect they are complicated filters affecting phase shift, resonances and frequency response fluctuations depending on the angle of arrival of the sound to the ear. While our brains sort these things out, they can sound a little funny when recorded (and played back especially on speakers, not headphones.) To hear how the pinnae affects these kinds of things, cup your hand behind your ear and bend it forward. Notice how the sound you're hearing changes - you're affecting those kinds of cues that your brain has gotten to know for localization.

[vorian]

Thanks for the info. I have read some about the binaural technique but I somehow missed that crucial part about the mic hearing from within an ear-like structure... that IS correct isn't it?

[Xavier]

One important factor in "3D" binaural sound it the effect of the pinnae and the ear canal on the sound - in effect they are complicated filters affecting phase shift, resonances and frequency response fluctuations depending on the angle of arrival of the sound to the ear. While our brains sort these things out, they can sound a little funny when recorded (and played back especially on speakers, not headphones.) To hear how the pinnae affects these kinds of things, cup your hand behind your ear and bend it forward. Notice how the sound you're hearing changes - you're affecting those kinds of cues that your brain has gotten to know for localization.

One interesting thing about this is that pinnae vary a lot beteen people. Not only size, but the depth of the ridges, and so on.

So, AFIK, our brains actually self-calibrate to our ears physical construction and shape. A learning process early in life teaches us the direction based on the "phase shift, resonances and frequency response fluctuations".

What is really cool is that the pinna helps us determine direction even with just one ear!

[Mark Alan Miller]

Xavier: yes, yes, and yes!