R&D Spirits
Toward High-quality and High-reality Teleconferencing
Yoichi Haneda
Senior Research Engineer, Supervisor
Speech, Acoustics and Language Laboratory
Acoustic Information Processing GroupNTT Cyber Space Laboratories

The rapid growth of IP (Internet protocol) networks has placed new demands on teleconferencing systems. NTT Cyber Space Laboratories has long been researching and developing teleconferencing systems focusing on an integrated type that combines a speaker and microphones
in one unit. These efforts have produced a 5th-generation teleconferencing product released at
the end of last year. To learn more about the technical features of this product, its acceptance by
the market, and future R&D goals, we sat down with senior research engineer and project director Yoichi Haneda.

Development of hands-free multipoint
teleconferencing systems—Dr. Haneda, could you tell us about your current
research endeavors?
Our group is currently researching elemental technologies and developing products for hands-free teleconferencing systems. The development of teleconferencing systems that use speakers and microphones
did away with the older handset-style of teleconferencing. These systems enabled users to manipulate
Far-endtheir computers, operate a projector, and perform
other tasks while carrying on a conversation, andenabled multi-participant meetings to be held. All inall, they made teleconferencing even more convenient. At the same time, replacing telephone receivers
with speakers and microphones generated acoustic
issues that did not previously have to be dealt with.
One of these is ambient noise and its reduction. Ideally, a microphone in a teleconferencing system will
pick up only human speech, but in reality, an increasing variety of peripheral sounds will be picked up as
microphone performance improves (Fig. 1), such as
Near-end

Network

Codec

Codec

Far-end speech
Ambientnoise
Echo

SpeechFig. 1. Problems of echoes, ambient noise, and volume for video and/or teleconferences.

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R&D Spirits

noise produced by fans in laptop computers and projectors or the sounds of air-conditioning equipment.
Such sounds might not be noticeable under ordinary
circumstances, but they can be bothersome during ateleconference. For this reason, one of our goals has
been to remove the noise component from a statecharacterized by a mixture of speech and noise.
Another issue is echoes and their cancellation. During a remote conversation using microphones andspeakers, the voice of a person talking at one end isreproduced by the speaker at the other end and in turnpicked up by a microphone at that end and returned tothe original talker via the network. A device for preventing this is called an echo canceller. We havedeveloped technology for suppressing both noise andechoes simultaneously. The third acoustic issue here
concerns volume control. In ordinary signal processing, speech produced near a microphone is reproduced more loudly than that produced far from a
microphone. An ideal teleconferencing system, however, would enable the voice of any participant to beheard at a fixed volume level. Another of our goals
has therefore been to control the speech volume ofeach participant in a teleconference.
These are our main acoustic-related issues in ourdevelopment work. Some of us are also researchingand developing speech codecs, and with theseresearchers included, our group consists of 17 members. As one of these members, my main role is toprovide direction for the entire project, but I am also
involved in audio signal processing research and themodeling of room transfer functions between microphones and speakers.
—What are the main technical features of thisresearch?
In noise reduction, the continuous sounds emanating from an air conditioner and computer fan aretreated as noise signals when stored, and they are suppressed by subtracting similar signals. An echo canceller, meanwhile, predicts the sounds that would be
conveyed from a speaker to a microphone and subtracts the predicted echo replica from the microphone
input signal. In principle, this is a relatively simple
process, but its implementation in product form
requires know-how such as in the appropriate settingof parameters. To this end, we have made good use of
research results accumulated over many years. For
volume control, our approach is to detect the direction of each participant’s voice using multiple microphones and to adjust the volume in each of thoseVol. 4 No. 2 Feb. 2006

directions using a specially designed algorithm. In
this way, we can reproduce a loud nearby voice as is,while making adjustments to only those voices thatare relatively far and subdued (Fig. 2).
—How is your research progressing?
Our 5th-generation unit went on the market at theend of last year (Fig. 3). This new IP (Internet protocol) teleconference unit, called the MB-1000, offers
the latest technology in noise reduction, echo cancellation, and volume control (automatic gain control). It
also features an improved sound-collection function.
While previous units required participants to speak
within a radius of one meter from the equipment, theMB-1000 can adjust and convey voices within arange of three to four meters all at a one-meter levelof volume. The MB-1000 also incorporates a 7-kHz
speech codec, which provides especially clear sounds
compared with ordinary narrowband telephone communications. Moreover, MB-1000 enables interconnection between the telephone network and the Internet. Last but not least, it can simultaneously connect
four locations, enabling four-point teleconferencing
using only these terminals. We are proud to say that
the MB-1000 represents a quantum leap in ease of use
compared with past teleconferencing systems.
—What future issues do you foresee, and how do you
plan to deal with them?
While we have definitely made great strides in
improving performance on various levels, there arestill a number of problems that must be solved if weare to achieve a teleconferencing system that is closer to ideal. For example, the MB-1000’s functions forautomatic volume adjustment for small voices andecho suppression are actually at odds with each otherfrom a technical point of view. In truth, part of thissystem is self-conflicting. This is the first problem
that we must solve.
Also, as an example of improving a basic teleconferencing function, we must make it easier for participants to understand the speech of other participants.
This could be achieved by bringing the sound-collection component of the system closer to each user suchas by using clip-on microphones or headset-type
microphones. But considering that users do not normally attach devices to themselves in ordinary meetings, this solution would probably be met with some
psychological resistance. For this reason, theapproach that we find most desirable is to use micro7

R&D Spirits

Speaker
Received
signalEcho

Loss control

Adaptive filter

Microphone
Speech A

Sent
signalEchosuppressor

Noisereduction

Microphonearray

Speech B
Ambientnoise
Echo suppression
for residual echo

Noise reduction Echo cancellation
based on short with adaptive filter
time spectrum
amplitude
estimation

Automatic gain
control fordifferent voicesat the same time

Fig. 2. Block diagram of the latest acoustic echo canceller.

Fig. 3. New IP teleconference unit.

phones that are built into the equipment and to handle
any reverberation that might occur by signal processing.
Next, as a long-term research theme, we want tofind a way of giving users a high-reality experience
when participating in a teleconference. Let me tell
you why. Strange as it may sound, trains and airplanes can be regarded as competitors to teleconferencing systems. While people have traditionally
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moved from one place to another by trains, airplanes,
and cars etc. to hold face-to-face meetings, telecommunication equipment has enabled people to holdmeetings without having to travel. As a result, achieving a sense of presence in which participants feel as if
they are all present at the same place is a very important function, and a desire for this function has, infact, been expressed by users. On the other hand, themeans of achieving a high-reality environment certainly differs between the bidirectional world as inteleconferencing and the unidirectional world as inmusic and movies. Most teleconferencing systems in
use today use only one speaker, but there are stillsome doubts as to whether the reproduction of threedimensional speech simply by using multiple speakers would enable a meeting to proceed smoothly. On
the contrary, such a configuration might even disturb
a user’s concentration. Such attempts at achieving
high-reality teleconferencing must be tested and themeaning of high-reality in the context of teleconferencing might also need to be redefined.

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R&D Spirits

Meeting user expectations with the highperformance MB-1000

use those needs as feedback in the development of
next-generation equipment as a matter of course.

—Could you tell us about R&D and market trends inteleconferencing equipment in Japan and overseas?

—Are you involved in any collaboration with othercompanies or universities?

Well, in terms of competing equipment, products
supplied by U.S. manufacturers have the largest market share at present. These products have become
well-known by virtue of their good performance andavailability in many countries throughout the world.
Here in Japan, a number of major electrical equipment manufacturers have been involved with teleconferencing equipment for some time, and in the lastyear, two new companies have entered the field.
You might therefore wonder where exactly does ourequipment fit among all the products that are being
offered. I think it’s fair to say that our equipment is
the most advanced in terms of basic functions. We arealso proud of its excellent cost-performance characteristics. Much to my regret, however, our equipment
is hardly as well known as that of U.S. manufacturers.
To rectify this, we have been aggressively promoting
our products both within and outside the NTT Groupby holding exhibitions whenever an opportunity arises. For example, last September we exhibited them at
the NTT Collection held by NTT West in Osaka,
Fukuoka, and Nagoya, and in December, we displayed them at the NTT Group Communication
Expo. At events such as these, it is common to exhibit equipment as company products, but we displayed
ours in the technology corner as research achievements of NTT Laboratories. This appeared to attract
greater interest in our products.

Yes, we are. We have a cooperative relationshipwith NTT Advanced Technology to conduct surveys
on market needs and to construct and evaluate prototype equipment. Our people and their people are constantly coming and going, and they have become an
important partner for us. We have also been interacting with universities through activities at academic
societies. In fact, many of our former colleagues now
hold teaching positions at universities providing uswith a wide range of contacts on an individual level.
Right now, however, we are not involved in any collaborative research related to product development.

—What kind of response did you receive from both
Japanese and overseas visitors to these exhibits?

My main field of study was physics, and I
researched solid-state crystal structures using lasers.
I chose physics as my major from the very start
because I believed that a knowledge of basic physicalproperties would prove valuable on whatever path I
might take in the future. Fortunately, a lot of emphasis was being placed on basic research in many fields
when I left graduate school in 1989, and physics
majors were in great demand. Against this background, I chose NTT as I believed its research environment was far better than that anywhere else. The
research of physical properties requires equipment ona large scale, and NTT has equipment and facilities
that surpass anything that universities or even othercompanies have. That was especially appealing tome, so with my strong desire to pursue research on
the basic nature of things, I entered the company.

The response was better than we expected! And our
improvement of the sound-collection function from
one to three-to-four meters was particularly wellreceived. Specifically, the capability of collecting
sound from points relatively far away from the equipment without having to connect external microphones was admired, as was the capability of picking
up even subdued voices and conveying short discussions among colleagues at one end in a realistic manner. We also received praise for the cost performanceof our MB-1000 unit from people familiar with thisfield. But at the same time, I am sure that additional
needs will be expressed once people begin to use theequipment in actual working situations. We plan toVol. 4 No. 2 Feb. 2006

—Could you tell us about any international activities
that you might be involved in?
In terms of individual technologies like echo cancellers and microphone arrays, the researchers incharge of those technologies make presentations atinternational conferences. As for myself, I am amember of the IEEE Audio Technical Committee.

Taking on diverse acoustic problems by aphysical approach—Dr. Haneda, what was your university major, andwhat expectations did you have on entering NTT Laboratories?

9R&D Spirits—What have been your main research themes up tonow?
After entering NTT, I was assigned for a while tothe acoustic signal processing section of the Human
Interface Laboratories. My job was to research methods of canceling echoes and to model transfer functions that could express the sound path from a speaker to a microphone. Then, in 1998 and 1999, I was incharge of consumer-oriented product development in
the Communications Equipment Business Headquarters that later became NTT East. This meant, inessence, the development of ISDN terminal adaptors.
At that time, ISDN was spreading rapidly, and withproducts changing every three months or so, it was ahectic time. Although it was hard work, the experience I gained there broadened my outlook considerably and has come to be immensely useful in my current work. During that time, I also obtained the Ph. D
degree for transfer-function modeling. In 2000, I
returned to NTT Laboratories, where I again undertook R&D work in the field of acoustics. Last year, I
was placed in charge of developing a directional AGC(automatic gain control) echo canceller, MB-1000.
As you can see from my history, I have been
involved with echo cancellers for some time, but thefact is, I do not feel entirely comfortable when I am
called an expert in echo-canceller research. This isbecause the most renowned of the several prizes that
I have received was for contributions made in directing research. Still, I might consider myself an expert
in bringing together various technologies in one
physical unit.
—What has been your goal throughout your R&D
activities?
The acoustic signal processing that we deal withincludes three basic elements: physical phenomena,signal processing, and human psychology. Amongthese, given that I majored in physics at university, I
have focused on physical phenomena associated withsound transmission from a speaker to a microphone
and have made the modeling of transfer functions
between microphones and speakers, which I mentioned earlier, my lifework. At the same time, theworld of signal processing is fascinating, and since it
is a relatively new technology, it tends to receive lotsof attention. Accordingly, in deciding what to pursue
in acoustics, I have always thought I should look forundeveloped themes in this field whose solutions
would prompt interest.
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And, from a different point of view, another of mygoals has been to build a foundation for myself as a
researcher. To survive in the world of R&D, it isimportant to decide what one’s forte is to be. It is also
necessary to take on an area of study that no one canbeat you at! I believe that I have pursued transferfunction modeling with the aim of laying a foundation as a researcher even more than out of simple
interest.

Toward the ultimate high-reality experience
focusing on human senses—Dr. Haneda, how would you like to expand yourpersonal area of research?
Well, for one thing, I would like to look a bit further
into the psychological aspects of acoustics. I am particularly interested in explaining the sensation ofhearing from both the physical and signal-processing
perspectives. At present, I am approaching this problem by creating various types of signals and examining how they are heard by people. But I would also
like to take this one step further and investigate whattypes of signals should be created to produce a certain
type of hearing sensation. However, my present role
is more of a “coach” than a “player,” and I find that I
have less and less time to research my personal areasof interest. Nevertheless, if I am to coach others withconfidence, and moreover, if I am to leave this role ofcoach one day, I must endeavor to build up myresearch expertise and achievements in a manner
appropriate for a frontline player.
—What is your ultimate dream as a researcher?
Aside from realistic considerations such as whattypes of technologies should be used, my ultimate
dream is to achieve a teleconferencing system thatcan provide a high-reality experience that makes
remote participants feel like they are sitting at thevery same table. This, of course, is a theme that has
been talked about for some time, and many
researchers even at NTT have approached this problem in various ways. My personal position is toapproach this task from the viewpoint of solving
acoustic problems in bidirectional communications.
For this purpose, I believe that a realistic approach is
to close the gaps between our ideal system and thepresent system in a step-by-step manner.

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R&D Spirits—What has it been like for you working at NTT Laboratories?
NTT Laboratories has been like a home to me—aplace where I feel protected. Indeed, I think of it as aplace where I can demonstrate my abilities to thefullest without restraint. In particular, the Acoustic
Information Processing Group that I presently belong
to has always been a very comfortable working environment. One reason for this is that each member ofthis group has expertise in core, elemental technologies that can be combined to create a single piece ofequipment. Covering the range from basic research toprototyping, development, and commercialization issomething that suits me well. Perhaps this is not sucha big job when viewed from NTT Laboratories as awhole, but I strongly feel that it is work worth doing.
—Dr. Haneda, what would you say to young researchers?
I would like to ask those who are about to enter theworld of R&D to ask themselves whether research issomething that they really want to do. I say this forthe following reason. There are many students inJapanese universities that, as part of the university
educational system, simply enter a laboratory andtake on whatever research theme is given to them as
opposed to expressing a true desire to become aresearcher. Such a state of mind can hardly lead togood research even if they enter a corporate researchlaboratory. True research is a process in which one
finds a problem on one’s own and attempts to solve it.
Research that follows the whims of someone else orthat becomes obsessed with details may have its merits as practice, but it is not something that a researcher
should fall into. I would therefore like to see young
researchers pursue a research area different fromthose of others. In this sense, I would say “Don’t takeVol. 4 No. 2 Feb. 2006

the same approach as someone else” to young
researchers.
In addition, I would like young researchers to placeparticular importance on ideas and approaches.
While there has been a tendency in recent years toplace emphasis on results, it cannot be said that
results are everything in R&D. For example, achieving a two-fold jump in performance simply by using
a higher computer processing speed has no particularvalue from an R&D perspective. What really determines value in the R&D process is insight andapproach. The true researcher is a person who holds
steadfast to personal strengths and uses thosestrengths to come up with original ideas and novel
approaches. I would love to see all young researchers
become just like that.

Interviewee profile■ Career highlights
He received the B.S. and M.S. degrees in physics
and the Ph.D. degree in information sciences fromTohoku University, Miyagi in 1987, 1989, and 1999,
respectively.
Since joining NTT in 1989, he has been investigating acoustic signal processing and acoustic echo cancellers. He is now a Senior Research Engineer in NTT
Cyber Space Laboratories. He received the President’sAward from NTT in 1995, the Outstanding Technological Development Award from the AcousticalSociety of Japan (ASJ) in 1995, the Young Engineer
Award from the Institute of Electronics, Information
and Communication Engineers (IEICE) of Japan in
1996, the Achievement Award of IEICE in 1997, theKiyoshi-Awaya Incentive Award from ASJ in 1998,
the Satoh Paper Award from ASJ in 2002, and thePaper Award from IEICE in 2002. He is a member ofIEEE, ASJ, and IEICE.

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