What is Binaural 3D Audio?
The Future of Audio.
Binaural or Binaural 3D audio is audio captured identically to the way we hear the world. When audio is captured with a binaural microphone like the Hooke Verse, it is capturing the exact location of every sound source and where it is in relation to the recordist upon capture.
Binaural Audio Is NOT Stereo
Binaural audio must be recorded with a binaural microphone.
A binaural microphone consists of two omni directional microphones wherein one mic is positioned very precisely within each ear. When a microphone is placed within the pinnae of each ear, a recordist is capable of recording audio identically to the way they hear it
How Does Binaural Audio Work?
Binaural sound is not to be confused with conventional stereo sound. Stereo audio allows for localization to the left and right upon playback. With binaural, a listener can localize sound sources in front of them, behind them, above and below. Stereo does not factor in the natural ear spacing or “head shadow” of the head and ears. These things happen naturally as a person listens, generating their own ITDs (Interaural Time Differences) and ILDs (Interaural Level Differences). Stereo recording is not capable of capturing these ITDs and ILDs.
In 1881, Clement Ader invents the first binaural audio system. Ader, who’d established the telephone network in Paris the year prior, installs an array of paired microphones at the edge of the stage of the Opera Garnier and transmits the audio via two phone lines — one for each ear — to listeners located two miles away. Later dubbed the Théâtrophone, Ader’s binaural system is eventually installed in theaters throughout Europe. It cost 50 French centimes per 5 minutes of listening.
World War I
During the First World War, both the Allies and Central Powers use a binaural audio apparatus to localize enemy warplanes. It consists of two receiving horns, spaced several feet apart and connected by rubber tubes to the ears of an operator. A similar binaural audio system made up of two hydrophones is used for localizing submarines.
Radio tech pioneer Franklin Doolittle comes up with the idea of broadcasting on two different bandwidths from the radio station above his shop in New Haven. The idea is to creates a clearer impression of the speaker’s voice. There are two microphones at transmission, each one broadcasting to a different radio, so in order to experience the multi-directional sound effect of Doolittle’s binaural audio system, the listener needs to own two radios.
Meanwhile, the man who will later be known as The Father of Stereophonic Sound, Harvey Fletcher, develops a pioneering binaural hearing aid for industrialist Alfred Dupont. According to Fletcher’s son:
Mr. DuPont, after his disillusionment with his audiologist, pleaded for something to help his hearing at meetings of his Board of Directors. He asked my father for assistance, and a binaural hearing set was devised. Two microphones were placed in the middle of the board-room table, and the telephone receivers were placed in a headband for Mr. DuPont to wear. The amplifiers, transformers, and condensers were housed in a cabinet under the table. The binaural system enabled him to sense the direction of the speaker, as well as to clearly understand the speech.
Fletcher goes on to become head of acoustical research at Bell Labs. He buys a mannequin from a wax figure dealer and mounting a microphone to each of its cheeks, birthing “Oscar”: the world’s first binaural dummy head. In 1933, Oscar debuts at the World’s Fair in Chicago. While one person is walking around Oscar talking aloud, fairgoers wearing headphones hear the voice from Oscar’s perspective, circling around their own ears. Minds are blown.
But Oscar isn’t the only binaural dummy head to appear in the ‘30s. Kornelis de Boer and Roelof Vermeulen of Dutch company Phillips outfit their own mannequin with binaural microphones — and to this day it’s still the only female head-based binaural audio system that has ever been created. (Ed note: That sucks.)
These experiments with binaural dummy heads dovetail with British engineer Alan Blumlein’s invention of stereophonic sound, which will soon overtake binaural as the viable cutting-edge audio technology for commercial use. Blumfield’s light bulb moment comes while watching a “talkie” at a local cinema with his wife. Like every other movie theater at the time, it has a single set of speakers, which sometimes creates a frustrating disconnect between the direction of the sound and the position of the actors on screen.
In 1931, Blumfield files patents for stereo records, stereo films and surround sound. Two years later, the first stereo discs are cut. And by 1937, Bell Labs is already demo-ing a proprietary multi-track stereophonic system for recording and mixing movie soundtracks…
The 1940s – 1960s
In 1940, Disney kicks off a sound revolution with Fantasia — the first commercial film released in stereo. “Fantasound” requires a multi-speaker system for playback; problem is, movie theaters aren’t equipped for that yet. “We know…that music emerging from one speaker behind the screen sounds thin, tinkly and strainy,” Walt Disney says. “We wanted to reproduce such beautiful masterpieces…so that audiences would feel as though they were standing at the podium with [conductor Leopold] Stokowski.” Fantasia gets shown at thirteen custom-renovated venues across the U.S.. Installation of the equipment proves costly, making a wide release impossible. But, over the next three decades, stereo systems for both commercial and in-home use gradually become more affordable. Stereo overtakes mono as the new standard, sidelining further experiments with binaural audio — at least for now.
German company Neumann unveils the KU-80 — the first commercial head-based binaural recording system — at the 1972 International Radio and Television Exhibition in Berlin. Similar dummy heads developed by Sony, JVC, and Sennheiser soon follow, providing creators with the tool they need to invent new ways of hearing. In 1978, Lou Reed employs a dummy head designed by German sound engineer Manfred Schunk to make Street Hassle — the first commercial pop album recorded in binaural audio — then follows that up with two more binaural albums, 1978’s Live: Take No Prisoners and 1979’s The Bells. (Read our roundup of The Best Albums Recorded in Binaural Audio.)
Meanwhile, BBC Radio 4 starts broadcasting binaural radio dramas, including a series centered on Sherlock Holmes and a 28-minute radio play that doesn’t contain a single word of dialogue — only binaurally recorded sounds — called The Revenge. Now, you might think that a radio play in which no one actually talks would make for a slow listening experience. But The Revenge hooks you from the get-go: a police siren blares and a chase ensues over land and through water. It feels like you’re the one on the run. (If you want to create a similar effect with the Verse, read How to Start a Binaural Podcast.)
In 1984, a non-profit audio production company in Upstate New York called the ZBS Foundation (“Zero Bull Shit”) releases a 72-minute binaural dramatization of the Stephen King novella The Mist. It takes place in a small New England town where a group of locals trapped in a supermarket have to beat back a siege of otherworldly creatures. Stereophile magazine raves: “The sense of depth and space is startling; the ambient feel of the environment combined with the sense of movement and positioning of the dialogue and highly effective sound effects makes for a memorable experience…Listen in a darkened room for maximum impact.” You can buy it on CD, download it on Audible, or: you can check out this fascinating podcast about the making of The Mist, which features excerpts:
Artist Janet Cardiff, together with her husband George Bures Miller, starts creating her critically acclaimed binaural audio walks. Cardiff guides the listener (“Turn left here…Go through that gateway…”) through site-specific soundscapes of her own design, which simultaneously alter and deepen the listener’s perception of the physical landscape. The result is a distinct type of audio-centric virtual reality, which listeners have experienced everywhere from London’s Whitechapel Library to New York City’s Central Park. More recently, Cardiff has started making binaural video walks, including one that guides you through the old train station in Kassell, Germany.
In 1994, a binaural audio film called Bad Boy Bubby wins the Grand Special Jury Prize at the Venice Film Festival and four AFI Awards (Australia’s equivalent of the Oscars). Bad Boy Bubby is a beautifully twisted black comedy about a 35-year-old man who leaves his abusive mother’s house for the first time in his life after being told since birth that the air outside is poisonous. To capture the sensation of experiencing the outside world for the first time, director Rolf De Heer sews binaural microphones sinto the wig of lead actor Nicholas Hope, one above each ear.
That same year, in the Tomorrowland section of the Magic Kingdom, Disney uses binaural audio to terrifying effect in its newest blockbuster ride, ExtraTERRORestrial Alien Encounter. Audience members are arrayed in a ring, strapped into seats with a speaker near each ear. When a power outage casts the room in complete darkness, a maintenance worker arrives — only to be ripped to pieces by a roaring carnivorous alien that proceeds to swoop around the room, terrorizing every helplessly immobile audience member with its close, spine-chilling breath.
Soon after, a Canadian Sound Studio called QSoundLabs puts out what has since become arguably the most popular binaural audio recording ever produced (with 25 million YouTube views and counting), “Virtual Barber Shop.” Sure, it may seem hokey next to binaural creations by Reed and Cardiff, but it’s hard to argue with “Virtual Barber Shop”‘s elegant simplicity. Your barber, Luigi, moves around your head, clipping away. When the clippers are louder in your left ear, you know he’s on your left side, and vice versa. It’s an auditory illusion that demonstrates just how dependent we are on being able to locate sounds in space. Stereo sound isn’t capable of producing that life-like sensation. Binaural audio does it perfectly.
How does wind effect binaural recording?
Wind effects binaural recording the same way it effects standard microphones. Wind noise occurs during outdoor use when wind hits the microphone diaphragm directly. The stronger the directivity of a microphone, the more prone it is to pop and wind noise. An omnidirectional microphone is barely susceptible, whereas hypercardioid or figure-of-eight microphones are very sensitive to pop and wind effects. Pop and wind noise can be muffled effectively by a foam wind shield (pop shield).
Can I play binaural audio on other speakers / headphones?
Once recorded, the binaural effect can be reproduced using any regular set of headphones or a dipole stereo. It does not work with mono playback, nor does it really work with loudspeakers as the acoustics of this arrangement distort the channel separation via natural crosstalk (an approximation can be obtained if the listening environment is carefully designed by employing expensive crosstalk cancellation equipment.) See Edgar Choueiri’s brilliant BACCH System or the Yarra 3DX speaker.
When did binaural audio first start pairing with video?
If you’ve been fortunate enough to experience binaural sound, you’ve probably only experienced it on the listening end. It’s difficult to pair binaural sound with video because both formats must precisely reflect the perspective of the recordist in order to function properly. If you were to wear a pair of binaural mics and record with a video camera that is positioned 6 feet above your head, the resulting media would be inaccurate. We need to make sure we are capturing video the way we see it with our eyes in order for binaural recording + video to work together. That’s why integrating with your GoPro, DSLR or phone’s built in camera is a no brainer because you hold them all to your eye or head when shooting.
What file format is a binaural audio recording?
A binaural recording is identical to a stereo audio file. Which means it’s a two track audio file. The two common types of audio are files are mono (one channel) and stereo (two channel). Ever heard a piece of music where you can detect specific instruments in different ears? That’s stereo. Ever heard a piece of music where every instrument is playing out of both ears? That’s mono, you can’t sense any directionality.
Either of these file types can be saved in whatever format you choose (.wav .mp3 .aiff etc.), which means a binaural recording too can be saved in whichever format you choose.
If binaural audio is recorded wirelessly, is there latency?
Not if you create your own codec! Which is precisely what we at Hooke Audio have developed. Most bluetooth audio codecs experience a latency time of around 150ms. This is a problem as humans will begin to detect sound arriving later than an image at around 80ms. However, there are a few Bluetooth chips on the market that use a high quality Bluetooth audio codec which transmits at very little latency.
What is the difference between 3D sound, 3D audio, mobile 3D audio, & binaural audio?
Truthfully, they’re all the same. The space is so new nobody’s quite sure what to call it yet, but at the heart of these marketing buzz words is binaural audio. Binaural audio dates back to the 1880s when French engineer Clément Ader created the Théâtrophone. Since then, binaural recording technology has advanced slowly, but steadily. At Hooke, we like to call it Mobile 3D Audio since we’re the only Bluetooth binaural microphone on the market.
When you listen to a binaural recording of a live concert, it makes you feel like you’re at the show. But as the ethereal crooner Perfume Genies proves on his latest album, No Shape, binaural audio can also be used to immerse you in the interior world of the artist. The story behind the making of the first single, “Slip Away” — which made for an amazing Song Exploder episode — shows just how much binaural can shape the creative process and inspire new types of music. Sound engineer Shawn Everett, who worked on No Shape with Perfume Genius (real name: Mike Hadreas) and Grammy-winning producer Blake Mills, recalls: “[Blake] really wanted to create different worlds, explore different sonic territories, and imagine a spatial field where you’re in the kind of wild place where Mike exists.” Hadreas discovered new territories as well:
“On headphones, it sounds like I’m singing in the center of the listener’s head. It took some getting used to, but I knew it helped communicate the songs more. It was almost like I was singing directly to someone.”
Last year’s release of Notes on Blindness: Into Darkness marked a watershed moment in the evolution of binaural film. It debuted at the Sundance Film Festival alongside the feature-length documentary that inspired it, Notes on Blindness, which tells the story of a writer and theologian named John M. Hull, who, over the course of many years, documented his steadily deteriorating vision on audio cassette. Into Darkness mixes those archival recordings with binaural audio and 3D animations to immerse you in Hull’s “world beyond sight.”
Canadian artist Janet Cardiff, together with her husband George Bures Miller, began creating her critically acclaimed binaural audio walks in the early 90s, but only recently has her innovative approach to sound inspired others to follow in her pioneering footsteps. Cardiff guides the listener (“Turn left here…Go through that gateway…”) through site-specific soundscapes of her own design, which simultaneously alter and deepen the listener’s perception of the physical landscape. The result is a distinct type of audio-centric virtual reality, which listeners have experienced everywhere from London’s Whitechapel Library to New York City’s Central Park. More recently, Cardiff has started making binaural video walks, including one that guides you through the old train station in Kassell, Germany.
Cardiff doubtlessly influenced the ad industry creatives behind Audio Tour Hack, whose binaural audio-inspired mission is to “use creative storytelling to redefine the way people perceive their surroundings.” Their first audio hack, “Artobots,” took place at the Guggenheim Museum in 2012. It re-imagines sculptures of crushed cars by artist John Chamberlain as remnants of a fictional war straight out of Transformers: “Commissioned by Megatron, Leader of the Decepticons, this exhibition celebrates the Decepticon’s annihilation of their archenemies, the Autobots. Each piece is artfully crafted from the wreckage of the fallen Autobot army. As you listen, one thing is certain…there’s more than meets the eye.”
Earlier this year, the BBC broadcasted the fourth episode in the latest season of Dr. Who on television, per usual. But a couple hours later it released an even spookier binaural version of “Knock Knock” online, which marked the first time a TV show has ever been produced in immersive 3D audio. The episode takes place in a haunted house, and you can hear the titular knocks coming at you from every direction: the walls, the ceiling, the creaky floorboards. In a video compilation of fan reactions, one excited Whovian spoke for all:
“When you think that something is there with you, your body immediately thinks you’re in danger. It brings the actual fear that they’re feeling in the show to you. Any minute, the monsters can come after you.”
Driven by the same impulse that led to a binaural version of Dr. Who, the BBC — which started putting out binaural radio dramas back in the ’70s — is now making a concerted effort to offer more of its radio programming in binaural. It remains a mystery that more podcasters aren’t taking advantage of binaural, be it to journalistically place listeners in the middle of a warzone, or to imaginatively transport them to a fictional world. After all, it’s easier than ever to start a binaural podcast. For inspiration, check out The Owl Field, which exclusively produces 3D audio dramas in various genres (horror, fantasy, action & adventure) that put you directly at the center of the story.
“Surely, no production on Broadway has ever thrown the doors of perception open as widely as The Encounter,” raved the New York Times when Simon McBurney’s one-man binaural show debuted last year. Accompanied by a binaural dummy head on a bare-bones stage, McBurney tells his headphone-wearing audience the true story of a National Geographic photographer who found himself lost in the Amazon rain forest. It has all the trappings of a classic adventure yarn — the kind you might hear around a campfire. But you also feel the very real sensation of time and space dissolving as McBurney’s voice and disorienting sound effects bounce around your ears.