Virtual surround sound for the living room

Stuttgart - Tension on a TV crime show is coming to a head: On the right a gangster runs off

into the dark of night, while horrified screams are audible to the left. Behind you the sound of

police sirens are growing louder.

If you have the right equipment, watching TV can feel more like being in the middle of the

action. This used to require five speakers and a subwoofer, known as a 5.1 system. There are

now several solutions available that produce surround sound using only two, and in some

cases even one, speaker. This is known as virtual surround sound.

"Virtual surround overwhelms the brain and the laws of physics," says Georg Wilde, a press

spokesman for electronics maker Philips. Virtual surround technology takes up less space

than 5.1 systems and requires fewer cables. Yet the sound is also different from traditional

surround sound systems.

"On the whole, though, it functions astonishingly well," says Christine Tantschinez from

Stuttgart-based Audio magazine.

Virtual sound achieves the highest audio quality, if the room is square or rectangular. Too

many niches and bays can be disruptive. Wallpapered walls are also better for sound than

glass or tile.

"The idea is to let the sound waves bounce off the wall like pool balls - with surround sound

coming out of the reflections," Christine Tantschinez explains.

Many systems require an exact measurement of the room to provide optimal sound results.

Some devices must also be harmonized with the television before being turned on for the first

time.

This set-up process is generally performed using some form of an easy on-screen menu

wizard. Some televisions now even come with an integrated virtual surround sound system

instead of normal loudspeakers.

Overly large or extremely sparsely furnished spaces can also diminish the virtual surround

effect.

"There's too much reverb there," says Matthias Rose from the Fraunhofer Institute for

Integrated Circuitry in Erlangen. The systems deliver good sound quality in a living room of up

to 50 square metres.

"You don't need to start rearranging things in your living room," Tantschinez says. Yet as

with true surround sound and in the movie theatre, the virtual set-ups do have a sweet spot.

That's the location where the listener feels like he's in the middle of the action.

For 5.1 systems, the loudspeakers are organized in circular fashion at a specific distance from

the listener, with best results in the centre. This isn't necessary for virtual surround systems.

Yet only one viewer on the couch will enjoy the central sound experience.

"Whoever sits in the middle hears everything best," Tantschinez says. Everyone else hears

more from the side on which they're sitting. Then again, this works the same way for

traditional sound systems with multiple little speakers.

Yet virtual surround sound isn't just of interest for the living room or for the speakers next to

the computer.

"The goal is to bring surround sound out into the mobile world as well, such as for portable

televisions or entertainment systems on airplanes," Matthias Rose explains.

That's why the Fraunhofer Institute is currently researching how best to transmit surround

sound via headphones using similar techniques to trick the human ear into perceiving sounds

from what seems like multiple sources.

"The signal is modified so that it is repeated directly in the ear as if it were coming from six

loudspeakers," Rose says.

There are already a variety of concepts being worked on to offer surround sound from just one

speaker. Yamaha, for example, uses what it is calls a sound projector to create bound sound

waves off one another, thereby producing the effect. Philips is working on a system called

Ambisound.

"The system is decked out with a multi-channel amplifier that works with expanded digital

sound processing technology that takes advantage of psychological/acoustic factors," Wilde

says.

The systems are available - to the extent that they are not already integrated into a television -

in both stand-alone and bundled versions, such as with DVD players. Prices vary based on the

technology being used.

While a sound projector costs around 500 dollars, an AV receiver including surround sound

system will cost around 1,000 dollars, Tantschinez says. "The more technology inside, the

more expensive the devices will be - there's no ceiling."

INFO BOX: The 5.1 multi-channel sound system

Most home theatre equipment produces surround sound using a 5.1 multi-channel sound

system. This means that a film's sound is output across five primary channels as well as an

additional channel for bass sounds. 5.1 multi-channel sound systems include left and right

primary speakers, a centre speaker, surround loudspeakers to the right and left as well as a

subwoofer to produce the low frequencies. Other 6.1 and 7.1 surround sound systems are also

available.
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By Verena Wolff, dpa