AUDIO EXPERIENCE FROM FRANCE
During the amazing Week of Sound, which took place a few weeks ago, I was able to attend a session organized by Radio France that focused on sound spatialization. I was particularly impressed by the demonstration of Wave Field Synthesis (WFS) technology, which can create an acoustic environment in which listeners can move around but have the same sound localization experience. This contrasts with 5.1 surround sound systems, which only really work when the listener is positioned at the center of the configuration.
For quite some time, Radio France has been interested in multi-channel audio as well as newer formats that allow listeners to experience sound differently. Their NouvOson site (which I mentioned in a previous post on my French version of this blog) starting offering audio programs recorded in 5.1 surround sound and binaural formats a year ago.
But what is binaural audio?
The way in which we perceive sound depends on three factors, and binaural audio accounts for them all. They are 1) sound-intensity differences between the two ears, 2) sound-timing differences between the two ears (for instance, the left ear will hear sounds coming from the right a few milliseconds later than the right ear), and 3) phase angle (the head’s position relative to the sound source). This last factor can affect the sound’s spectral quality, which is further modified by the shape of our ears’ pinnae. However, from the time of our birth, our brains have been subtly managing all three categories of information, memorizing different combinations and then using them to intuitively identify where a sound is coming from.
Hervé Dejardin, an acoustical engineer and a member of Radio France’s Innovation and Quality technical team, likes to describe the binurnal format in the following way: “In fact, the idea is to recreate the acoustic environment that would be experienced by our two ears if we were listening to the sound in nature.”
It is actually quite easy to experience binaural audio: you just need a computer or a smartphone that has a stereo jack, and it is imperative that you use over-the-ear headphones or, worst case scenario, earbuds. Binaural audio offers us the possibility of traveling to the heart of a sound universe and having true-to-life acoustic experiences.
Binaural audio is incompatible with HIFI systems
Comfortably seated on my couch, at the apex of the classic isosceles triangle formed by the stereo system, I tried out several binaural audio recordings; I can tell you right off the bat that the result was very disappointing. Hervé Dejardin confirms that “binaural audio is not made to be listened to on speakers. The only way to reproduce the binaural experience using speakers is by using transaural audio.”
Indeed, the stereophonic configuration accounts for the “crosstalk” that takes place when someone is listening to speaker-broadcast sound (each of the listener’s ears perceives the signals coming from both the right and left speakers). The transaural approach therefore deals with crosstalk by using a set of crosstalk-canceling filters and ultimately leads to the reproduction of the binaural experience that would have been possible with headphones; this means that the right and left ears only hear the signals that are intended for them specifically.
The production of binaural audio requires that sound be recorded in the binaural format. This is possible using a special piece of equipment, a sort of super microphone that is composed of three microphones located at its front end and two mini-recorders towards its back end. Radio France uses a DPA 5100 microphone, and the six-channel 5.1 surround sound recording is then transformed into the binaural format using a software program.
There are also artificial heads (Neumann heads) that you can use, which have two microphone inserts embedded in the ears. These types of recording sessions need to take place under studio-like conditions because these super microphones have the ability to capture 360 degrees of sound. This includes “parasitic” sounds, such as the noise produced by a studio audience, for example.
A format used by radios and for public events
As a broadcaster, Radio France is clearly interested in these new types of formats that are starting to be developed. It is already using them on the airwaves; for instance, “Interceptions” is a news program broadcast by France Inter, and it is possible to listen to it in either binaural audio or 5.1 surround sound on the program’s website.
Radio France bet that the success of these new audio formats would also be partially determined by the originality of program content, which reminds us that program production is also one of the group’s core businesses. Putting together news programs is all well and good for Radio France’s listeners, what does the group offer music lovers? In January, the NouvOson website gave listeners a chance to experience a live transmission of a performance of Requiem de Berlioz in binaural audio; it is an incredible piece of orchestration: the orchestra comprises 190 musicians and the chorus is composed of 160 singers, who are the core of a rather theatrical orchestration that also includes four brass bands placed at the four cardinal points of the cathedral. You can listen to the binaural version of the concert in its entirety here.
This sort of offering should become more and more common in the coming months because Radio France is currently setting up studio 105 so that it can transmit concerts to its audience using WFS. For several years, certain music festivals have been making their concerts available in these formats. You can bet that this sort of approach will become more and more common when it comes to live music. The fact that mobile audio equipment is available to the masses is a major avantage for all those people who want to immediately become immersed in the world of binaural audio. However, this phenomenon may also end up progressively changing our way of listening to music, which could marginalize traditional high-fidelity systems in the future.
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Some particularly true-to-life musical pieces available in binaural format :
(Headphones or earbuds are absolutely indispensable )