The Science of Audio for Headphones

The Challenge And The Future

Headphones have been a genius invention by all accounts for music lovers: They bring 2 key benefits for the listener: First, by bringing the speakers right against the ears, the brain can process a signal which is undistorted by other external sources, or even the air layers and its movements between the speaker source and the listener in a typical auditorium. Second, by being against the ear, the power requirement is of course significantly reduced, allowing much lighter apparatus, providing unparalleled comfort, and of course, providing privacy.

Headphones speaker hardware quality has been improving slowly but regularly over the last decades, both for professional studio use and consumer electronics, with the successive rises and falls of nomadic devices, from the Walkman to the MP3 players of the turn of the century, to the now ubiquitous smartphones. But both academic and private research in the industry have pointed to a major focus shift over the last 2 years, in no small part due to the smartphones, or more precisely, the impressive computing power they now pack.

Originally, the industry was focused on making headphones being able to deliver a signal that was as close as possible to the original source.  In that endeavor, headphones R&D were treated not any differently than classical external speakers.

Thanks to heavy investment by academic and some key private contributors such as Sennheisser and Bose,  specific research started to target how to improve the shortcomings of headphones: By virtue of good passive (and sometimes active) sound insulation, headphones are actually unable to create the original "real life" sound experience which, above and beyond the pure quality of signal, is also the result of air vibration over longer distances, as much as reverberation against nearby walls and objects. Natural sound provides all those clues to our brain to build a geo location of the sound sources, a sense of depth perception of music and sound that is essentially obliterated by the headphones being positioned against our ears. In other words, as much as high end headphones make their very best to deliver a signal as close as possible to the original sound, they will always lack the natural 3D sound that is so familiar to our brain. That's why even high end headphones sound, as dynamic as they are, will always essentially feel "flat" (not in tune, but in depth perception) to consumers.

Both the private and Academic sectors have clearly identified the issue and rush to re create the 3D experience that provides our brain this dopamine discharge and feels so natural. In a well published 2016 paper in Applied Science,  Guttierrez- Parera and Lopez of the Poytechnical University of Valencia, Spain,  titled "Influence of Quality of Consumer Headphones In the Perception of Spatial Audio" focusing on Headphones tests, "Spatial impression (locations, sensations of depth, immersion, reality of the audio event)" are tested. The general consensus in the industry is that this spatial rendering is the key to bring the next level of high quality to headphones for consumers. Beats Electronics publicly acknowledges it with their own analysis, in a paper from Atkins and Giacobello titled "Trends and Perspectives in Signal Processing in Consumer Audio" : "Opportunities for signal processing research lie in... the presentation of three dimensional spatial audio". An IEEE research paper of 2015 refers to an article by Sunder et al., titled "Natural Rendering for Headphones " in three dimensional audio.  

As much as the new Eldorado of 3D natural sound is clearly the key to unleash a new class of headphones, smartphones have been a disrupting force that totally bent the research in that field.  The industry is unanimous: reaching this goal requires to be able to process the signal of the headphones to "trick" your brain and re create the three dimensional spatial experience.  Make no mistake: we are not talking here of simple signal filtering , like an EQ system, of signal gateway or filtering systems can provide. The processing power requirement to reach this result is extremely heavy,  and the semi conductor industry knows how to make it : the solution is called DSP, (Digital Signal Processor), a heavy duty processing unit specifically tailored to a high number of simultaneous calculations, process analogic to digital signal processing. DSP are very powerful, and very expensive. More over, the silicon needs to be finely tuned specifically to the exact technical characteristics of the headphones. While research was going heavy on incorporating DSP silicon into consumer headphones, but did not make it outside of the labs for understandable costs reasons, Apple and other smartphone makers were progressively bringing immense computing power in the palm of the consumer hands, and in 2016 the audio industry was quick to realize that rather than affixing an expensive piece of DSP hardware to  give birth to the next generation of high end headphones, they could rather tap into the now powerful silicon running Android and iOS by way of DSP software.

DSP software is a cutting edge field, especially when it comes to running it on portable devices. The maths involved is highly complex and subject to many Intellectual Property protective patents. It is nothing short of a miracle that a software app can emulate such a powerful beast as a silicon DSP. 

The race is now on : Xtyle Odeon is the first brand to bring a genuine SPAS Class headphones to the market, (Signal Processing Assisted Sound), the first to successfully re-create the 3D natural sound our brain loves and is used to.  Its first product, Wave Beach 3D, is nothing short of a technological breakthrough with an advanced DSP software running on both iOS and on Android, optimized and tuned for its state of the art stereo wireless hardware. Xtyle Odeon has partnered with Global Delight, the world software leader in this niche of DSP software. Led by mathematical , algorithm genius and music lover R. Bhat, the outcome of the partnership is outstanding and ground breaking. The user can control the 3D effect right from its Boom companion app, tailored made for Wave Beach 3D specifics. This is the first SPAS Class headphones on the market. Others will follow in 2019.

To learn more about Wave Beach 3D, click here

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