An Australian company has developed headphones that use sound wave technology to tailor the product to a user’s unique hearing profile – and achieved a record Kickstarter fundraiser in the process.
The idea for the headphones came about when Kyle Slater, co-founder and CEO of Nura, was doing a PhD at UC Berkeley when he started talking to an engineering friend about what would make the perfect pair of headphones.
The two engineers quickly realised it was impossible to make a definitive list of specifications because everyone hears sounds differently, so perfecting a pair of headphones seemed impossible.
A year later, a collaboration with Luke Campbell, a medical doctor and now the CTO of Nura, came about.
“Basically, we were working on some hearing diagnostic stuff, and started to think about this idea again,” Slater said.
“I asked him one day whether the thought it was possible to put a hearing measurement machine into a pair of headphones, and he thought it was.”
While Campbell was still a little skeptical, the pair started working through the calculations and realised their idea was achievable.
Hearing profiles
Each person has a unique way of hearing sounds and has different sensitivities to sound frequencies.
“The way to think about this is that if you were sitting in a car playing around with the treble and the bass and the mid, you can hear the change that it makes to the sounds, and everyone's familiar with that experience,” Slater said.
“That’s what our ears are doing. Our ears shape the sound in the same way.”
Nura has tapped into this aspect of hearing to create headphones that measure an individual’s hearing profile by picking up the faint sound that the cochlear generates in response to sounds it hears, called otoacoustic emissions.
This technology is typically used to test hearing in newborns and children by placing a small earphone with a sensitive microphone into the baby or child’s ear and testing how the cochlear responds to audio stimuli. A functioning cochlear should produce a small acoustic emission in response to sound, which is picked up by the microphone.
Nura uses this technology for its headphones to develop a hearing profile to determine the listener’s sensitivity to different frequencies of sounds.
For example, some people might be more sensitive to bass, while others are more sensitive to high frequencies.
“It’s surprising the natural variation that happens with everyone just due to their anatomy and due to their genetics,” Slater said.
Once the microphone in the Nura headphones picks up the soundwaves from the ear, it is then processed using digital signal processing built into the headset, which plays two roles.
“It first allows us to process the sounds that come back out of the ear so we can build the hearing profile,” Slater said.
“But we then also use it to actually modify the sound as we play it. When we learn about how someone hears, we then re-equalise the music so it’s a good match,” Slater said.
The development phase for the headphones lasted around nine months, with the team not only working on the electronics, but also doing tests to work out what the best shape and fit would be, which involved measuring around 100 ears to make the headphones as universal as possible.
During the development, Slater said the product went through some major changes in its size.
“It was a really big box with a whole bunch of electronics in there. There was a lot of redundancy, because obviously we weren’t sure exactly what we needed,” Slater said.
“It was very big. Once we worked out exactly how it was going to work, we were able to miniaturise it and remove some of that redundancy.”
Difference in design
The Nura headphones have a unique design with both in-ear buds and over-ear cups.
However, the initial design started with just in-ear buds with an external box.
“We had some issues with noise – external noise – and isolation from that. We started putting the ear buds into a pair of cans to help isolate that. Then we thought that’s a little bit of a shame that we have to do that, but at least it’s good, we can put the electronics there,” Slater said.
“After that we realised there’s a big difference between earphones and headphones in terms of the experience and the way that you feel the sounds, because with earphones you don’t really feel the soundwaves around your ear.”
To give a better user experience, Nura introduced a speaker into the outer ear cup to give a more immersive experience.
There were other benefits to this design, such as isolating noise within the headphones so sound wasn’t emitted outside the headphones.
“Now we don’t really see it as an ear bud inside a pair of headphones. It’s evolved a lot more to take on its own unique archetype. We just think about it as a new type of interface,” Slater said.
Nura’s priority now is shipping the headphones to customers from the Kickstarter, which was the most funded Australian Kickstarter campaign ever, raising $1.8 million.
The company also plans to work on other products to give users an improved experience when it comes to listening to music, whether it’s in the car or elsewhere. Work will also continue on refining the headphones, and potentially producing sports headphones.
“In the future, we just believe that there are lots of improvements that can be made to consumer audio and to the way that we actually listen to music,” Slater said.