Provided you have two functioning ears, one on either side of your head where they’re meant to be, you hear things in the real world in stereo. For nearly a century, we’ve also been able to use two speakers or headphones to listen to recorded music in stereo, but that hasn’t always been the case.
Before the invention of stereophonic audio, music was consumed monophonically. While there are still some scenarios where playback systems are set up in mono, most media formats now contain at least two audio channels, a left and right.
With spatial audio technology making its way into consumer audio equipment, stereo audio as we know it may soon become a thing of the past too. In this article, we investigate the gradual transition from mono audio to spatial audio over the past 150 years.
What is Spatial Audio?
Before we turn back the time machine, let’s quickly define the commonly misunderstood term spatial audio. Spatial audio refers to audio that is designed to replicate the effect of surround sound, immersing the listener in what they perceive to be three-dimensional audio. Spatial audio is not the same thing as Dolby Atmos, although some spatial audio systems do rely on the Dolby Atmos format.
1877: The First Audio Recordings and Reproductions
While working on the telephone and telegraph, the American inventor Thomas Edison also developed the phonograph, which became the first device to record and reliably reproduce audio. The contraption interpreted engravings on the outside of a metal cylinder and then converted those engravings into audio.
Despite being somewhat of a breakthrough at the time, by today’s standards, the technology is somewhat primitive; audio could only be recorded and played back in monophonic.
1887: The Wax Record
Ten years after the first audio recordings, the technology had advanced from metal cylinders to wax disks. These became known as gramophone records and came in a format that can be compared to the modern-day record player and vinyl record.
While gramophone records began to achieve some level of commercial success in consumer audio, they still only contained one channel of audio and were therefore monophonic. Over the coming years, the metal cylinder died out while the wax record took over.
1890: The First Commercial Stereo Audio System
In the early 80s, Clément Ader routed a number of audio signals from the Paris Opera to the Paris Electrical Exhibition, allowing attendees to place one receiver to each ear and listen to the Opera live, in stereo. Despite finding some commercial applications in restaurants and cafes, the concept of stereo audio still didn’t make it into the world of recorded and reproduced audio.
1933: The First Stereo Recordings
Some 40 years after the last major advancement in stereo audio, the renowned record label EMI was paying royalties to an American company called RCA, in exchange for using their audio recording system. Eager to circumnavigate these costs, EMI hired the English engineer Alan Blumlein to develop their own bespoke audio recording system.
While working on this recording system, Blumlein’s attention was already on his next invention. During a visit to the cinema, he observed that the sound remained static, while characters moved across the width of the screen. His solution was to record one audio signal from the lefthand side of the film set, and one from the right. Each channel was then played out of their respective speakers to create a stereo listening experience.
Alan Blumlein continued to develop this system, which he had dubbed ‘binaural’. By 1934, he had produced the first records which contained independent left and right audio signals. This gave listeners a new sense of immersion that was not possible with previous recording techniques.
1936: The Distraction of Television
Throughout the course of the 30s, the likes of Alan Blumlein, Walt Disney, Bell Laboratories and others continued to scope out potential applications for this new stereo technology. Although they still had Blumlein on their books, EMI wasn’t convinced by the commercial viability of stereo records.
Having been commissioned by the BBC to develop the first television system, EMI instead opted to task Alan with working on that project, instead of continuing his work on stereo sound. He continued to work on television until EMI halted all progress at the advent of World War Two.
1960s: The Beatles’ Adoption of Stereo Sound
Despite being the home of Alan Blumlein’s first stereo audio experiments back in 1934, it wasn’t until 1958 that the world-famous Abbey Road Studios decided to adopt Alan’s stereo sound technology. They installed the world’s first stereo mixing console, the REDD 17.
It wasn’t just Abbey Road that had previously disregarded the technology, though. Blumlein’s binaural audio project essentially lay dormant for nearly 30 years. Upon its resurrection, a little-known band called The Beatles adopted the technology in their recording and mixing practice.
Renowned for being true innovators in the musical and technological domain, The Beatles immediately took stereo technology to the extremes. They used the REDD 17 console to hard-pan instruments one way, while vocals were hard-panned the other, thus creating a unique listening experience.
While unique, hard-panning instruments in this way caused elements of a mix to disappear when only heard on one speaker. As the 60s unfolded, the process of recording and mixing in stereo continued to be refined.
Early 1970s: Quadraphonic Audio
If monophonic audio has one channel and stereophonic audio has two, there are no prizes for guessing how many channels quadraphonic audio has. While Ampex and Telefunken were experimenting with the concept of four-channel audio in the 1950s, it wasn’t until the 1970s that the technology became practically and commercially viable.
By positioning a speaker at each corner of a quadrilateral space, audio could be positioned along the Y axis, as well as the X axis. Although bands such as Pink Floyd dipped their toes in the world of quadraphonic audio, the required hardware to record, process and play quad-sound meant that the technology didn’t really land.
Despite its commercial misfire, the invention of quadraphonic audio laid the foundation for surround sound and is essentially what we would now call 4.0 surround sound.
1982: Surround Sound in a Domestic Environment
As we’ve already established, there were examples of surround sound up until this point, including Dolby’s own analogue surround sound systems that were intended for use in commercial cinemas in the late 70s. In 1982, Dolby introduced their Dolby Surround system, designed to work with VHS tapes in a domestic setting.
Using a matrix encoding system that is far too complex to explain in this article, movie enthusiasts were finally able to enjoy their favourite films in surround sound. A year later, Dolby introduced Dolby Digital which allowed for a separate Low Frequency Effects channel, or LFE.
It was at this point that the “4.1” system naming format came to be, with the first number representing the number of regular speakers and the second representing the number of subwoofers.
Over the coming years, audio-visual technology moves through several key stages including DVD, Dolby Digital EX and Blu-Ray, with improvements to their surround sound technology at each phase.
2012: 128 Audio Tracks with Dolby Atmos
While DVD’s attempted transition to Blu-Ray is hardly seen as a success story, Dolby Surround’s graduation to Dolby Atmos certainly is. To coincide with the launch of Pixar’s Brave, Dolby installed its first Atmos-capable system in 2012
This allowed for up to 128 tracks of audio to be played out of 10 speakers in a 7.1.4 configuration (with the final digit representing the number of overhead speakers). For the next decade, there were approximately one thousand commercial Atmos installations per year, and that doesn’t include Atmos-capable home-speaker setups.
2021: Apple Music Adds Spatial Audio Support
In September 2021, Apple announced the third generation of their Airpod wireless earphones. With it, they announced their Spatial Audio for Apple Music functionality, which utilises Dolby Atmos as well as 5.1 and 7.1 signals to give listeners a more immersive listening experience.
2024: Spatial Audio for All
Until the widespread adoption of spatial audio-capable hardware such as Airpods, surround sound was reserved exclusively for audiophiles, cinema-goers and those lucky enough to have a surround sound system in their home. Now, consumer-grade headphones can offer some level of spatial audio at a fraction of the cost.
Some mobile phones, laptops and soundbars now make use of advanced technology such as upward-firing speakers and sound virtualisation to simulate surround sound in a home environment. It’s now easier than ever to mix Dolby Atmos-compatible audio, and even subscription services such as Netflix have introduced spatial audio support in order to keep up with the times.
What’s Next for Spatial Audio?
It’s hard to say what’s next in the world of spatial audio, although it’s safe to assume that the current technology will become more accessible, more affordable and more convincing as it continues to evolve. Who knows, spatial audio may even come to Spotify at some point in the future.
