Single speaker unit creates surround sound

12 November 2003

A home theatre system that produces surround sound using a single speaker unit has been unveiled by a US company.

Film soundtracks are normally mixed for five or six separate speakers arranged around a cinema. This can be used to create the impression that action is happening all around the audience.

Many DVDs include this sound data so that the effect can be recreated at home. But a listener normally has to wire up five or six speakers in set positions around a room.

Nirotek’s DVD player, the NIRO 1.1 PRO, achieves the same effect with five individual speakers packed horizontally into a single case. To achieve the surround sound effect, an on-board computer manipulates the signal to each speaker using algorithms that mimic the effects used by the brain to identify the direction a sound is coming from.


Transfer functions

These “head related transfer functions” take account of differences in the time at which a sound arrives at each side of the head, as well as subtle distortions caused by the shape of each ear.

The signal manipulations require 600 million calculations per second. Nirotek also claims its system does not require the listener to be directly in front of the speaker to be effective.

Clare Newsome, of UK magazine What Hi-Fi, believes that there could be substantial interest in such a system. “A lot of people love surround sound in the cinema but don’t want speakers all around the room,” she told New Scientist. “If it’s done well, it can work incredibly.”

The NIRO 1.1 PRO DVD system costs $799 and is being sold exclusively online. “No rear speakers means no cables and no clutter,” says Nirotek’s Lonnie Pastor. “The NIRO 1.1 automatically gets spouse approval.”