You may have seen terms like spatial audio, 7.1, DTS, surround sound, and 3D sound in marketing materials when shopping for headphones—and not just for gaming headsets—but how does surround sound in headphones work exactly?
Let’s dig into the history of surround sound, learn a little about the tech that makes headphone surround work, and take a look at the competing standards.
How did surround sound evolve in movie theaters?
Surround sound was developed to make watching a movie more exciting and to extend the experience beyond the boundaries of the screen. It may seem like a relatively recent idea, but it’s been around for a while.
Among its many technical innovation credits, The Walt Disney Company claims the first documented commercial use of surround sound in film. For the release of the studio’s revolutionary animated film Fantasia in 1940, it unveiled a multichannel sound system called Fantasound. The full 54-speaker setup was only installed in two theaters. Although that system was impressive, the concept proved too complex and expensive for most theaters. Consequently, film surround sound died out completely by the 1960s.
Starting with the release of Dolby Stereo in 1976, and no doubt helped massively by the success of Star Wars (1977), Dolby drove the mass adoption of surround sound in theaters throughout the 1980s and 1990s. Over that period it iterated from the 4-channel Dolby SR, to the 6.1/7.1 channel Dolby Digital Surround EX. Other companies, such as Digital Theater Systems (DTS) and Sony, brought their own technologies to the surround sound game. Upping the ante once more, the Dolby Atmos immersive sound system was unveiled in 2012, which added height information via ceiling-mounted speakers. DTS produced a competing product in its DTS:X.
How did surround sound arrive at home?
After some attempts to push 4-channel quadraphonic sound equipment into the home market in the 1970s, surround sound really arrived in living rooms in 1982 with the introduction of 3-channel Dolby Surround. This was upgraded in 1987, with Dolby Pro Logic for a total of four audio channels.
Home surround sound went digital in 1995. Just like the full theater version, home Dolby Digital is a 5.1-channel system. The competing DTS system launched as a home version a year later. Dolby Digital EX and DTS-ES are both 6.1/7.1-channel systems, and add extra rear surround channels. Dolby Atmos home theaters are compatible with conventional 5.1 and 7.1 layouts. For example, a 7.1.4 Dolby Atmos system is a conventional 7.1 layout with 4 overhead or Dolby Atmos “enabled” speakers.
Can you get surround sound in headphones?
We only have two ears, but we can differentiate between sounds coming from in front and from behind, as well as left from right, above, and below without even moving our heads. Ever wondered how we do this?
Our head-related transfer function (HRTF) refers to the effect our shoulders, head, and outer ears have on sound waves coming from different sources before they encounter our eardrums. Those physical interactions impact the levels, timing, and phase relationships of the different frequency content of the sounds we hear. As part of our hearing system, our brains have learned to decode all those changes to decipher where the sound likely originated in the space around us.
If you placed tiny microphones inside your ears and captured the signals, they would include the effect of your HRTF. You would have a binaural recording that works perfectly for you when played back over headphones. In fact, even with a generic HRTF created using a dummy head or person-shaped object, the effect can still be quite impressive.
By obtaining and reproducing these signals in a controlled way over headphones, you can reproduce an auditory event in space and experience it in an extremely lifelike way. So 2-channel recording can capture surround sound. Despite being the oldest form of surround sound, binaural recording continues to occupy a niche, with recent products from Sennheiser making use of the technology.
What’s the difference between “true” and “virtual” surround sound headphones?
Movies and games come with multichannel audio intended for playback over loudspeakers for multiple listeners, and there are two distinct approaches to making surround work over headphones:
- Hardware: Headphones featuring multiple speaker drivers on each side, located around the ear in a manner that reflects the optimal location for each channel’s speaker. This is known as a “true” surround headphone.
- Software: External or internal processing is added to a standard headphone that takes the multichannel audio stream and applies some kind of HRTF-based binaural algorithm to place those audio channels in virtual space around each ear. This is known as a “virtual” surround headphone.
True surround is mechanically complex and results in large, expensive, heavy headphones, but requires only the basic multi-channel decoding that a home theater receiver has been able to do for years. Virtual surround doesn’t require special headset hardware, but needs heavy signal processing to create a convincing virtual soundfield.
The virtual surround approach is also superior because, when combined with head motion tracking, it’s possible to lock the position of the virtual surround speakers, so the sound sources don’t shift with the wearer when they turn their head. This makes the experience far closer to the movie theater or in-game experience they are mimicking. So far this is only available in more advanced systems that include motion tracking technology.
As digital signal processors have become cheaper and less power-hungry, virtual surround headphones have made the hardware surround sound approach basically obsolete. As is the case with new technologies, there are many competing implementations of virtual surround sound in headphones.
What are the main competing virtual surround sound standards?
These technologies have a few things in common. The surround sound signal is processed in real time and rendered as two channels for headphones. Where the processing happens depends on the application and specific hardware configuration. Audio processing can occur in software on the gaming platform (such as PC or Xbox One), a base station that transmits the audio to the headset, in an external amplifier/processor, or in the headset itself.
Here are the most prevalent virtual surround systems for headphones right now:
Dolby Atmos for Headphones
Dolby Atmos is the apparent leader of the pack when it comes to object-based surround sound in headphones. It has headphone implementations for the PC, Xbox One, Xbox Series X/S, and mobile phones. It works by using audio signal processing to convert the Atmos object metadata into a binaural 360-degree output for the headphone’s two drivers. This technique is a major improvement over the previous Dolby Headphone technology, allowing for hundreds of channels of sound to be processed into a virtual surround sound experience.
Headphone:X is another high profile, proprietary object-based surround sound system. It can also take multichannel streams and convert them into surround sound for your headphones. As well as providing a full multichannel movie theater experience, it can use and enhance gaming audio spatial cues to make the gaming experience totally enveloping.
Creative Super X-Fi
Creative calls its Super X-Fi technology audio holography for headphones, using complex algorithms and computationally intensive techniques. By taking three photos of your face and ears with your phone, a custom fit is created for each user through a sophisticated head and ear mapping process. It is available in a portable headphone amplifier package, as well as the company’s headphones.
There is a virtual surround sound solution available for free included in your Windows 10 OS, called Sonic. You can access it by looking under audio device properties: Windows Sonic for Headphones. Even if a movie or a game doesn’t explicitly say it works with Windows Sonic, the feature will enhance the experience, regardless of the source material.
Apple Spatial Audio
Apple’s spatial audio is designed to deliver 3D surround sound exclusively to their AirPods (3rd generation), AirPods Pro, and AirPods Max headphones. This feature arrived as part of iOS 14 and uses head tracking in specific hardware configurations, making it one of the more advanced offerings currently available.
Sony 360 Reality Audio/3D Audio
Sony also has its own versions of object-based surround sound, for both music listeners and gamers. To enjoy 360 Reality Audio for music with your headphones you need to download its mobile app and take a picture of each ear. Those photos will generate a personalized sound profile which can be uploaded to one of the supported streaming services (Deezer, Nugs, Tidal). PlayStation 3D Audio works with any headphones, as well as its own, provided you have a PlayStation 5. An HRTF profile can be selected for the best effect.
Audio plugin maker Waves’ high-end 360-degree surround sound system enables you to experience movies, music, and games with realistic 3D sound. This is probably the most sophisticated contender, advancing the way headphones deliver 3D audio by combining room emulation and motion tracking, to immerse listeners into a virtual reality audio environment. It’s easiest to find this bundled with high end gaming headsets like the Audeze Mobius and HyperX Cloud Orbit S.
What should you look for in surround sound headphones?
Except where noted, all the software-based surround sound systems we’ve listed here will work with your regular headphones, so either start with the ones you already own, or start looking for a pair with some guidance from your friendly neighborhood SoundGuys!
As for which processing solution to choose, this really depends on your application and platform, be it PC gaming or watching movies on your tablet or phone. Most can be tried for free and are regularly updated and improved, so see what works best for you. When you’re testing them out, make sure you don’t have more than one surround system operating at the same time as results will likely be weird and unpredictable!