The technology behind binaural audio (also known as 3d Audio) is more than a century-old. So why are most people only now beginning to hear about this superior alternative to stereo sound? Mostly because in order to experience binaural audio, you need to be wearing headphones, which used to be a lot less common than they are today. A binaural audio recording captures sound as you actually hear it by employing two microphones spaced to approximate the distance between your ears. With headphones on, binaural audio produces the incredibly immersive sensation of being in the same exact place where the recording was made.
When binaural audio was invented in the late 19th Century, amplifiers didn’t exist. The only way to listen to electrical audio signals was through a telephone receiver earpiece, and every radio came with a pair of headphones until the mid-1920s. But the introduction of the moving-coil loudspeaker changed all that, paving the way for stereophonic sound, which, by the end of the ’30s, was being demo-ed for movie soundtracks. Binaural slid into the background — until today. Now, every smartphone comes with a pair of earbuds. We crave immersive experiences. And creators in every sector (VR, music, podcasts, gaming…) are tapping the limitless potential of binaural.
Here, in the first of a three-part series, we’re taking a look back at the birth of binaural and the pioneers whose early experiments made the listening experience of the future possible. We’ll pick up where we left off with Part II next week.
The Late 19th Century
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…