PRESS RELEASE 6 /202 3

The Man Behind the Neumann KU 100: An Interview With Stephan
Peus

Berlin, June 14, 2023 – This year marks the 50th anniversary of the Neumann dummy headmicrophone. We spoke with our former President of Development and former General
Manager, Stephan Peus, for whom “Fritz”, as the Neumann dummy head is fondly called,
was a constant companion. And has remained so to this day! For in retirement, he foundedpeus-recording to specialize in dummy head recordings.
Dear Mr. Peus, you started at Neumann in 1974, shortly after the first dummy head microphoneKU 80 saw the light of day.
That's correct, the KU 80 was introduced at the 1973 IFA trade show. I had already becomeacquainted with it before that because I was studying communications engineering and acoustics
at the Technical University of Berlin. During that time, I met the three inventors of the dummy head,Kürer, Plenge and Wilkens, and took part in the final acoustic tests. My first contact with thefinished KU 80 was the recording of a piano concerto by Brahms, which had been recorded in thelarge auditorium of the SFB (now RBB) on a big studio tape machine. I was thrilled to be entrustedwith the editing.
One might think that a dummy head microphone is just a mannequin’s head with two mic capsules
in its ears. But it's not as simple as that, is it?

No, because high-quality recordings
require a signal-to-noise ratio thatcannot be achieved with tiny
capsules that would fit in the earcanal. That's why Neumann wasapproached right away. Here, they
could be certain to get the required
quality. However, the difference indiameter from the ear canal of about
6 mm to the 21 mm diameter of thesmall-diaphragm studio microphoneused causes strong coloration.
Therefore, acoustic filters had to beinstalled to combat the resonances
Stephan Peus in conversation with Andreas Hau
and reflections. However, these filters
and the reproduction of the entire ear canal were the reason why the first dummy head KU 80
sounded impressive only over headphones. Incidentally, the reference was Sennheiser's HD 414,
the first open headphone, which was extremely popular at the time and triggered an initialheadphone boom. Over loudspeakers, however, recordings with the KU 80 sounded muffled.
The poor loudspeaker compatibility was already fixed in its successor, the KU 81, launched in
1981, wasn’t it?
The impetus came from the Institut für Rundfunktechnik (IRT) in Munich. Some employees of theTU Berlin, who had developed the dummy head, had transferred there. They looked atconventional stereo microphones, especially the Neumann SM 69, and concluded that a dummy
head microphone should be diffuse-field equalized. After all, it is usually positioned at somedistance from the sound source, i.e., outside the so-called critical distance. At the same time, adiploma thesis brought the realization that the outer ear’s acoustic impact reaches only a few
millimeters into the ear canal. So, it was possible to shorten the ear canal in the dummy headconsiderably, which greatly reduced the attenuation of the upper frequencies. Together with diffuse
field equalization, this was a major step forward. However, to facilitate production, I implemented
the acoustic filter inside the KU 81 differently than in the IRT design. That was great fun, because I
finally got to apply what I had learned in acoustics lectures. Before that, everything I really needed,
I had learned at Neumann. Of course, I had the acoustic understanding, but the university didn’t
teach you how to build a good-sounding microphone.
Another important innovation in the KU 81 was that new silicone materials made it possible toreproduce the human outer ear in a much more complex and differentiated manner. This has led toa higher resolution.

But the Neumann dummy head never had a torso, did it?
The KU 80 was originally sold in a carrying case as wide
as our shoulders. So, when you mounted the head on it,
you had the upper part of the torso. It was assumed thatwas important for directional imaging, until one realizedthat a shoulder section is only relevant for head rotation,
when it creates different reflection angles. But with a rigid
mount, the torso plays no role in directional perception.
That's why we didn't include a shoulder-width case with theKU 81 and KU 100.
After the KU 81 remedied the KU 80's biggest shortcoming
by providing good speaker compatibility, what were themotivations for developing the KU 100?

The KU 80 und KU 81 had a more „human“ appearance.
.

Acoustically, the KU 100 is indeed not all that different fromthe KU 81, nor were there any major quirks that absolutely
had to be fixed. However, we had contact with a very
interesting designer who found the KU 81 so ugly that heoffered us a design draft – which we liked right away!

The more abstract form actually also corresponds to the current state of research that, for example,
very human-like robots tend to appear uncanny, while artificial forms, which clearly identify
themselves as something technical, meet with fewer reservations.
There's something to that! At the very beginning, the KU 80 was used in theaters and in thePhilharmonie Berlin to allow the director to listen 1:1 into the room. And there were indeed protests
from actors and from the audience that a “dead skull” was hanging up there. So they built a cubewith black gauze in which the head disappeared.
But the KU 100 does offer some detail improvements over its predecessor?
Yes, one of them being the shape of its ears. In the KU 80 and KU 81, we worked with casts of realears. In the case of the KU 80, they were the ears of one of its developers: Dr. Henning Wilkens; inthe case of the KU 81, they decided to use the ears of an employee of the Ruhr UniversityBochum, who unfortunately died in a traffic accident a few years later. But his ears live on, so tospeak. In principle, the ears of the KU 100 are the same, but since our outer ears (and hence thoseof the first dummy heads) are never perfectly symmetrical, I had the idea to match the ears of theKU 100. This was to prevent the asymmetries of the KU ears from accidentally overlapping with

those of the listener’s ears in sucha way that the result could
become too right- or left-biased.
And because I had no way ofmeasuring and eliminating thisasymmetry automatically, I did thealignment by hand. My daughter,
who is a dental technician, gaveme suitable materials, and so I
worked on the ears of the KU 100
from sculpting paste with aspatula and scraper. I took one of
the ears as a reference and madethe second one as much like amirror image as possible.
My impression is that the frontal localization is more accurate on the KU 100 than on the KU 81.
This could be in part due to the improved symmetry of the ears. We have also changed the “pitchangle” of the ears somewhat. In listening tests with the KU 81, it had been noticed that soundsources in the horizontal plane usually tended to be perceived slightly upward during reproduction.
This is related to a characteristic “dip” in the horizontal frequency response of our outer ears. For
every natural ear, that dip is at a slightly different frequency. This does not interfere with natural
hearing, because we “adjust” the location of sound sources with the help of our eyes throughout
our lives. If we are now given a certain configuration by the dummy head, we cannot correct
visually. As it happened, the aforementioned dip in the horizontal frequency response of the KU 81
caused sound events from the front to be perceived as slightly shifted upward. In the KU 100, wetherefore adjusted the angles of the ear cups relative to the vertical so that the imaging is now
correct horizontally and vertically.
Since your retirement, you have gained a lot of experience in dummy head recordings with "peusrecording". Would you have any tips?
I have been careful to work only in acoustically “nice” and balanced rooms, often in churches. A
sound check is essential, of course, to determine a good position for the dummy head. And you
should watch out for unwanted background noises. In “normal” recordings, microphones are usedthat can largely block out sound from irrelevant directions. The dummy head, by its very nature,
listens in all directions, and you should be very careful to assess the overall acoustic situation
before recording. Nothing remains hidden from a microphone as sensitive as the Neumann dummy
head!
Thank you very much for the interview, Mr. Peus!
The interview was conducted by Dr. Andreas Hau (Content Marketing Manager, Neumann)

Link: Find out more about the Neumann KU 100
Stay up to date and follow us on: FACEBOOK I INSTAGRAM I YOUTUBE

About Neumann
Georg Neumann GmbH, known as “Neumann.Berlin”, is one of the world’s leading manufacturers of studio-grade audio equipment andthe creator of recording microphone legends such as the U 47, M 49, U 67, and U 87. Founded in 1928, the company has beenrecognized with numerous international awards for its technological innovations. Since 2010, Neumann.Berlin has expanded its
expertise in electro-acoustic transducer design to also include the studio monitor market, mainly targeting TV and radio broadcasting,recording, and audio production. The first Neumann studio headphones were introduced in 2019, and since 2022, the company has
increased its focus on reference solutions for live audio. With the introduction of the first audio interface MT 48, and its revolutionary
converter technology, Neumann now offers all the necessary technologies needed to capture and deliver sound at the highest level.
Georg Neumann GmbH has been part of the Sennheiser Group since 1991 and is represented worldwide by the Sennheiser network of
subsidiaries and long-standing trading partners. www.neumann.
Press Contact Neumann:
Andreas Sablotny
andreas.sablotny@neumann.com
T +49 (030) 417724-19
Raphael Tschernuth
raphael.tschernuth@neumann.com
T +49 (030) 417724-67