Headphones have been around for over a hundred years, but recently there has been a surge in new technologies, spurred on in part by the explosive popularity of Beats headphones. In this blog, we will look at three advances in headphones arising from high tech start-ups. I’ve been introduced to each of these companies recently, but don’t have any affiliation with them.
EAVE (formerly Eartex) are a London-based company, who have developed headphones aimed at the industrial workplace; construction sites, the maritime industry… Typical ear defenders do a good job of blocking out noise, but make communication extremely difficult. EAVE’s headphones are designed to protect from excessive noise, yet still allow effective communication with others. One of the founders, David Greenberg, has a background in auditory neuroscience, focusing on hearing disorders. He brought that knowledge to the company. He used his knowledge of hearing aids to design headphones that amplify speech while attenuating noise sources. They are designed for use in existing communication networks, and use beam forming microphones to focus the microphone on the speaker’s voice. They also have sensors to monitor noise levels so that noise maps can be created and personal noise exposure data can be gathered.
This use of additional sensors in the headset opens up lots of opportunities. Ossic are a company that emerged from Abbey Road Red, the start-up incubator established by the legendary Abbey Road Studios. Their headphone is packed with sensors, measuring the shape of your ears, head and torso. This allows them to estimate your own head-related transfer function, or HRTF, which describes how sounds are filtered as they travel from to your ear canal. They can then apply this filtering to the headphone output, allowing sounds to be far more accurately placed around you. Without HRTF filtering, sources always appear to be coming from inside your head.
Its not as simple as that of course. For instance, when you move your head, you can still identify the direction of arrival of different sound sources. So the Ossic headphones also incorporate head tracking. And a well-measured HRTF is essential for accurate localization, but calibration to the ear is not perfect. So their headphones also have eight drivers rather than the usual two, allowing more careful positioning of sounds over a wide range of frequencies.
Ossic was funded by a Kickstarter campaign. Another headphone start-up, Ora, currently has a Kickstarter campaign. Ora is a venture that was founded at Tandem Launch, who create companies often arising from academic research, and have previously invested in research arising from the audio engineering research team behind this blog.
Ora aim to release ‘the world’s first graphene headphones.’ Graphene is a form of carbon, shaped in a one atom thick lattice of hexagons. In 2004, Andre Geim and Konstantin Novoselov of the University of Manchester, isolated the material, analysed its properties, and showed how it could be easily fabricated, for which they won the Nobel prize in 2010. Andre Geim, by the way, is a colourful character, and the only person to have won both the Nobel and Ig Nobel prizes, the latter awarded for experiments involving levitating frogs.
Graphene has some amazing properties. Its 200 times stronger than the strongest steel, efficiently conducts heat and electricity and is nearly transparent. In 2013, Zhou and Zettl published early results on a graphene-based loudspeaker. In 2014, Dejan Todorovic and colleagues investigated the feasibility of graphene as a microphone membrane, and simulations suggested that it could have high sensitivity (the voltage generated in response to a pressure input) over a wide frequency range, far better than conventional microphones. Later that year, Peter Gaskell and others from McGill University performed physical and acoustical measurements of graphene oxide which confirmed Todorovic’s simulation results. Interestingly, they seemed unaware of Todorovic’s work.
Graphene loudspeaker, courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley
Ora’s founders include some of the graphene microphone researchers from McGill University. Ora’s headphone uses a Graphene-based composite material optimized for use in acoustic transducers. One of the many benefits is the very wide frequency range, making it an appealing choice for high resolution audio reproduction.
I should be clear. This blog is not meant as an endorsement of any of the mentioned companies. I haven’t tried their products. They are a sample of what is going on at the frontiers of headphone technology, but by no means cover the full range of exciting developments. Still, one thing is clear. High-end headphones in the near future will sound very different from the typical consumer headphones around today.