Using Your Head - Binaural Recording

Don't forget to read Part One of this article: Moving Beyond Mono - Stereo Recording

In attempting to capture a soundfield the way our ears capture it, you have to consider the role that your head plays in how your ears pick up sound. Several recording techniques have different ways of accomplishing this.

Jecklin Disk

Jecklin Disk The idea of using an absorptive baffle between two omni directional mics was first proposed by Alan Blumlein, but later refined by Juerg Jecklin.

Jecklin's baffle was 300mm in diameter, made of 3/8" plywood covered with about 1" of foam and sheepskin on each side. The precise thinckness of the baffel doesn't appear to be critical. More important is the 165 mm (8 inch) distance between the two omni directional mic capsules.

You can construct a baffle from what ever you can get your hands on. Good results have been obtained by gluing two mouse pads to a clipboard. You could also buy one from Josephson Microphones or MBHO.

One possible modification to the Jecklin disc (called a Schneider disk) is to cut two 1/3 sphere "cheeks" from a Nerf ball and to attach them to the disc. This method is a hybrid of the Jecklin disk and the Theile sphere adopted by Schoeps.

Dummy Head

If we are attempting to emulate the way a pair of human ears hear, one thing we might try would be to construct a model of a human head and place microphones where the ears are. Here are links to some examples. These models also seek to replicate the reflections that take place in the outer ear.

Head in use

Two practitioners of this technique are Gordon Hempton and Tchad Blake.

Visit Gordon's homepage and listen to some of his nature recordings

Visit Tchad's homepage, and read an interview with Tchad in Tape Op #16.

You could also try to build your own dummy head.

For more binaural sound files and informative links, visit the Binaural Sound Page or

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Headworn Microphones

If carrying a dummy head is not practical, you could try to use your own noggin to simulate a human head and place small microphones either in or near your own ears. These types of systems are the subject of much discussion on the (very active) DAT-heads mailing list.

Several mic systems are comercially available: And there are also many DIY plans available:

If you have a two lavaliere microphones in your kit, you can construct an inexpensive binaural mic setup to experiment with.

I own a variety of lavaliere mics, all terminated in Switchcraft TA-5F plugs for use with Lectrosonics wireless transmitters. Here is how the transmitters are wired. Here is how the mics are wired:

I built a "Y" cable using two Swithcraft TA5M plugs to mate with the lavaliers and feed the signal to a mini (3.5 mm) TRS jack. My Sony TCD-D8 DAT deck provides about 1.5 DC volts through its mic jack to power the lavaliers.

Here are the wiring pinouts of other popular wireless mics.

My biggest problem with head-worn mics came when I became hyper-aware of turning my head. I thouight that any movement of my head would shift the stereo field, so I focused all my attention on keeping my neck and shoulders perfectly still. Talk about a tension headache! This is not the case - moving your head doesn't mar your recording, but this was a big mental hurtle, and Iım sure that it is just a question of getting used to the process.

I also tried using directional lavalieres, and found that this only worked well when recording bands in a loud club.

PZM techniques

Crown SASS-P MkII The Crown SASS(stereo ambient sampling system) mic consists of two PZM microphone elements built into a near-coincident array. The SASS produces spectactular results (just listen!) but it is a little heavy. This is might be one to avoid if you were backpacking, but it's a great sounding stereo microphone. You can run it off phantom power, or you can use internal 9 volt batteries.
 

An aproximation of the SASS mic can be constructed by mounting two PZM mics on hingled panels as shown below:

Crown published The PZM Boundary Booklet: A Basic Primer and Experimenter's Guide, which was reprinted in Microphone Manual (Design and Application) by David Miles Huber (ISBN 0-240-80141-5). Both titles are out of print, but Microphone Manualmay be avaiable at your local library. Other techniques for stereo recording using PZMs are detailed in Stereo Microphone Techiniques by Bruce Bartlett.

You could use Crown PZM mics, but far cheaper are the PZMs made by Crown, but marketed by RadioShack. These are no longer sold, but if you find some for sale, get them, because they can be modified for better results.

The Cutting Edge

The Holophone is a spin off of Mike Godfrey's dummy head binaural recording research: a "point-and-shoot" microphone - the first specifically designed for surround sound playback.

Visit the Holophone homepage which contains links to specifications and reviews.

The Holophone

Links

Here are some links to interesting material beyond the scope of this article: