By Brett Crockett, Senior Director of Sound Technology Research
One of the things that makes Dolby Atmos movies so lifelike is their use of overhead sound. In real life, helicopters fly over our heads, birds sing from the trees and sometimes — especially if you have kids – the sounds of laughter and roughhousing come from the rooms upstairs. Being able to recreate those sounds makes a Dolby Atmos® experience much more realistic.
But creating overhead sound can be a challenge. Cinema owners solve the problem by installing two rows of speakers on the ceilings of their auditoriums. But to bring Dolby Atmos to home theater, we had to find an easy way to create overhead sound in living rooms.
Of course, if you already have speakers in or on your ceiling, or are willing to install some, they will likely work fine in a Dolby Atmos system. But many people don’t have ceiling speakers, and they can’t install them or don’t want to go through the hassle.
To solve that problem, we tapped into our deep knowledge of how the human brain perceives the world around it. Using that science, we learned to hack your hearing to create incredibly realistic overhead sound without actually having speakers over your head.
Development of Dolby Atmos enabled speakers
Working closely with our hardware partners, we developed Dolby Atmos enabled speaker technology. These speakers are specially designed to create overhead sound even though they sit at the same level as traditional speakers. They emit sound upward, where it reflects off your ceiling down toward where you’re sitting.
But simply reflecting the sound signal off the ceiling isn’t enough to produce truly convincing overhead sound. That’s why we have to reverse engineer your hearing.
Humans are able to locate sounds in three dimensions, and the way we do it is nothing short of amazing. A great example is how we detect overhead sounds.
As sound passes over our outer ears, they act like filters, modifying the sound. The way sounds are modified changes depending on where a sound originates. If the sound comes from above, the brain detects the changes mainly at high frequencies. Since it is these high frequencies that are most important in detecting overhead sounds, Dolby Atmos enabled speakers tightly focus these higher frequencies toward the ceiling.
In addition, Dolby Atmos enabled speakers filter these high frequencies to mimic the natural filtering imparted by our ears when a sound comes from overhead. The filtering signals to your brain, “this is a sound coming from above me.”
The effect is so convincing that some people who heard early demonstrations of Dolby Atmos home theater couldn’t believe that there were no speakers over their heads. They would climb up on chairs to examine the ceiling and make sure we hadn’t hidden speakers there.
You can learn more in our white paper about Dolby Atmos enabled speakers. But what’s even better is to experience them for yourself. In the coming months, retailers in a number of countries, including Magnolia Home Theater and Magnolia Design Centers in the U.S., Future Shop in Canada, Sevenoaks Sound and Vision in the United Kingdom, and AVAC Corporation in Japan, will have Dolby Atmos demo rooms. Once you hear Dolby Atmos enabled speakers, I think you’ll agree that the sound is remarkable. You may even find yourself standing on a chair, peering at the ceiling.