Re: "El Cheapo" dummy heads?

[Henrik Møller <hm@xxxxxxxxxx>]

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I can only support Peter's (and other's) ideas of "home made" dummy heads. It may

give you a lot of fun.

The first step of getting something better for headphone reproduction than
traditional recordings is very easy. Spaced microphones, possibly with a sphere
between - as proposed - is excellent. (There are also commercial "sphere"
microphones, as far as I remember from Schoeps). If you make your own head, you
should use pressure type microphones, and they can be obtained from a dollar and
up.

The second step is to use a real head. In fact you get the best dummy head
recordings FOR YOU, when you record in your own ears. In order to get the perfect

sound, make sure to equalize the headphone and the whole system; it should have
a flat frequency response when measured on your head and with the microphone you
record with, still in the same position. I can especially recommend that you
insert the microphones in earplugs. (Then you won't hear the sound during
recording, but you can enjoy it many times afterwards). You can read about
details
in our paper:

- Henrik Møller, Michael Friis Sørensen, Clemen Boje Jensen, Dorte Hammershøi:
"Binaural technique: Do we need individual recordings ?", Journal of the Audio
Engineering Society, Vol. 44, No. 6, June 1996, pp. 451-469.

Third step, going to a dummy head is actually one step back for the reproduction
of space as compared to individual recordings, but for most applications
individual recordings are not really feasible. Dummy heads aim at copying an
average human acoustically. Unfortunately, that is not an easy task, since we are

so different, especially when it comes to the pinna. We have tested dummy heads
in several investigations, and a summary is given in the May issue of the Journal

of Audio Engineering Society, which just dropped into my mailbox a few days ago.
(Is it only in Denmark that journals are always delayed?):

- Pauli Minnaar, Søren Krarup Olesen, Flemming Christensen, Henrik Møller:
"Localization with binaural recordings from artificial and human heads", Journal
of Audio Engineering Society, Vol. 49, No. 3, May 2001, pp. 323-336.

Talking about the price of dummy heads, there are reasons why they are expensive.

They come with high quality microphones with low noise, usually also
preamplifiers, maybe phantom power, and possibly some more electronics. The
channels are matched, and sensitivity and frequency response are stable. And the
head itself must be produced, often in low numbers. Some heads have mechanically
complicated ear simulators in order to comply with international standards for
various purposes. (Many of the heads are actually not really made for recording).

Henrik Møller

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