Sounding off

A new upgrade for home theatre enthusiasts provides as many as eight listeners in a room with the same surround-sound experience.

Home theatres have always had a tricky quirk: in an average-sized room, the best sound would go to the listener in the middle, and everyone else had to settle for special effects that could sound far away or out of place.

Now, following years of research into how humans perceive sound, audio engineers have infused a home-theatre receiver with software that automatically detects room acoustics, speaker placement, and other information at eight unique locations and then processes the sound to give each listener the “sweet spot.”

Called MultEQ and developed by Chris Kyriakakis and his colleagues at Audyssey Laboratories, the technology is a product of research into “immersive audio” by Kyriakakis and others at the Integrated Media Systems Center (IMSC) at the University of Southern California, one of the National Science Foundation’s Engineering Research Centres in the US.

To set the system up, a user first has to place a microphone in any one of the listening locations.

The home-theatre receiver then performs a calibration function by playing a test tone through the main and surround speakers, a tone that is modified by each speaker’s unique design characteristics and location – and further altered by the reflections of the sound bouncing off the walls of the room. The listener repeats the process for each location, such as three spots on a couch, two on a loveseat and one more on a recliner.

During the calibration procedure, the MultEQ algorithm detects how each listening position is different and independently compensates for all of them, simultaneously modifying the sound to improve the experience for each person in the room.

Alternative approaches to provide multiple sweet spots have been developed by audio companies, but those algorithms average sound data, a process that can yield problems when sound waves cancel each other out.

The researchers have recently adapted their process for car audio systems, a venue which has to compensate for far more obstacles such as window reflections and each listener’s proximity to the various speakers.

Available for integration in low-cost, high volume home theatre products, the MultEQ technology is offered exclusively with the Aureus audio DSP solutions from Texas Instruments.