Do you know what the difference between a car and a flying car is? Only one goes up. This vertical dimension plays a crucial role in distinguishing Dolby Atmos from traditional surround sound technologies. Speaker systems designed for Dolby Atmos not only incorporate speakers at the listener’s level but also include overhead speakers to add a new height aspect. The technology goes a step further by utilizing speaker arrays and binaural processing to leverage psychoacoustics, enhancing the auditory experience. If these terms seem complex, don’t worry. We’ll simplify them into more understandable concepts across two posts. By the end of our exploration, you’ll appreciate how Dolby Atmos doesn’t just use conventional speaker directionality, but also taps into the way we perceive the sounds around us to transport us to another world.

To grasp the essence of surround sound, it’s essential to comprehend what a channel is and how sound engineers manipulate a virtual soundstage of channels to craft the desired auditory landscape. Mono (monophonic) sound employs a single channel, mixing all sounds—be it instruments, vocals, or ambient noise—through one channel, ensuring uniform sound distribution whether you’re using one speaker or two hundred. Concerts, for example, are mixed in mono to guarantee a consistent music experience for every attendee, regardless of their position in the venue. Shifting to stereo (stereophonic) sound introduces two channels, allowing for distinct sound production by left or right speakers. This approach offers a more lifelike sound experience, enabling audio mixers to pan sounds, creating movement across the soundstage. Stereo mixing is the most common audio experience, especially when it comes to music played through headphones or in a personal studio. Further incorporating two additional channels for rear speakers introduces the ability for sounds to move diagonally, laying the groundwork for surround sound.

As discussed in a previous post, we delved beyond simple panning to include dynamic volume and frequency range adjustments. In a nutshell, a bigger speaker can produce louder and deeper sound. A 3.1 sound-system setup, stretching from left to center to right, offers a broad spectrum of sound directions, enhanced by a subwoofer dedicated to low frequencies. (Previous sentence is wholly awkward; rewrite) Adding rear speakers expands the soundstage into a 3D experience, leading us to the popular 5.1 surround sound system. This setup comprises five full-bandwidth channels directed to tweeters or woofers, with a separate channel for the subwoofer, facilitating a comprehensive audio landscape from any direction.

Dolby Digital 5.1 surround sound is well known for the unique processing and encoding by Dolby technologies, not a specific line of speakers. While Dolby produces high-end professional speakers, its 5.1 surround sound technology is widespread in consumer speaker systems across various brands. Dolby Digital processing operates within a channel-based framework, mixing audio specifically for the speaker setup.

Dolby Atmos, much like Dolby Digital, formats and processes audio in a unique manner. It introduces “audio objects” that can be precisely positioned and moved in a three-dimensional space, adding height channels to introduce a vertical dimension absent in traditional surround-sound systems. Through these height channels, overhead speakers allow the system to produce audio from any direction, from a plane flying overhead to a giant green lizard crushing a car to your right. By integrating front, rear, and overhead speakers, a 5.1 surround sound system evolves into a 5.1.4 setup, adding four overhead channels to the traditional five, complemented by a subwoofer for low-frequency effects.

Imagine standing in a forest with your eyes closed. You can “see” the wind rustling through the trees and hear a stream flowing over smooth stones. A 5.1.4 surround-sound system can place these sounds with precision if the soundstage of the scene matches the size of the sound system. But how can Dolby Atmos capture the essence of an eagle soaring far overhead or the resonance and grandeur of the Grand Canyon in your 200 square foot living room? It achieves this through clever binaural processing and frequency manipulation, tricks designed to fool your brain, offering a glimpse into the capabilities of Dolby Atmos we’ll explore further in our next post.