April 2017 CNBC.com Modern Medicine

For the 360 million people worldwide who lack some or all of their ability to hear, technological interventions have already come a long way. But still, they're not perfect. Scientists are working on a number of experimental techniques that may soon transform hearing interventions. That could greatly improve the quality of life for millions, who have been waiting a long time — the last major innovation in hearing technology occurred in 1985.

Normal hearing is more simple than it may appear. Sound waves move through the ear canal and pulse the ear drum, which then moves the tiny bones inside the middle ear. They in turn tap the cochlea, which converts mechanical signals into electrical ones, which it then passes to the auditory nerve, which transmits it to the brain for processing.

Hearing in miceBut the ear presents a difficult engineering problem. If any of these parts are disrupted, a person might lose some or all of her hearing. And what kind of intervention works best depends on which part is affected. For those who lost hearing later in life, more sophisticated devices might be the first big step to improving hearing. Tobias Moser, a professor of auditory neuroscience at the University Medical Center Göttingen, is working to improve the function of a cochlear implant by turning it into an optical device instead of an electric one. Instead of turning sound into electrical signals to be transmitted to the brain, as current cochlear implants do, this technique turns sound into light. Micro-LEDs flash onto genetically altered neurons, which send the information to the brain. "This sounds really fancy — it's very cool — but it's also not so easy. This is putting optoelectronics into a pretty aggressive environment [in the ear]," said Moser. He and his team have already shown that the device works in rodent models. In the next four years, before it can be tested in humans, they hope to try their technique in other primates and improve the capabilities and hardiness of the device itself.

Other scientists are turning to other senses to encode information usually communicated audibly. "We're used to thinking that we have five senses, but that's actually not the case — we have tons of different types of sensory receptors in the body," said Scott Novich, the co-founder and chief technology officer at start-up Neosensory. The sense of touch, for example, actually processes pressure, pain, temperature and vibration, each through a different type of sensory receptor in the skin, Novich said. Novich and his colleagues are developing a commercially available version of VEST, their research project that uses sensory substitution to map sounds onto the skin before the information is transmitted to the brain.

Initial trials show that it takes some time to train the brain to understand these signals, and Novich doesn't expect VEST to replace hearing aids necessarily — it could compensate for frequencies of sound that hearing aids might not transmit well, or even augment the nuance of information that wearers receive. Neosensory is doing participant research now and hopes to start manufacturing a product in about a year.

Some researchers are going past devices and working directly on the body's cells to restore hearing. Stefan Heller, a professor of otolaryngology at Stanford University, is figuring out how to revert inner ear cells to their earlier, functional state in order to restore hearing. It's an ability that birds have and mammals lack, so Heller and his team have been working to understand how cells tell each other to regenerate. In five to 10 years, they plan to start testing a few drug compounds on humans. If all goes as planned, their discoveries wouldn't offer a cure for hearing loss but could give people with degenerative hearing loss the option to take a drug and delay getting a hearing aid. Albert Edge, a professor of otolaryngology at Harvard Medical School, is also looking into regenerating cells to restore hearing. But his lab has focused on the hair cells inside the cochlea and the neurons from the auditory nerve connected to it. Four years ago Edge and his collaborators discovered that certain molecular compounds could help hair cells regrow, which led to an improvement in hearing in mice. That showed them it could be done, but the effect was not as dramatic as they would have liked, said Edge. Armed with more knowledge about how cells regenerate elsewhere in the body, Edge and his team have been exploring how various drugs can encourage the regrowth of hair cells and neurons. Ultimately, drugs, which would likely have to be injected deep into patients' ears, could be tailored to individual needs. "What's attractive about our approach and others like us is that our aim is to restore the ear to what it was," Edge said. The goal is providing alternatives to people for whom hearing aids are not a good option. Edge's work is still limited to Petri dishes and mice, but his team hopes to start some small clinical trials in a few years.

For those with inherited hearing loss, many of these approaches won't work. If a person had a genetic mutation that caused the cochlear hairs to die off, taking a drug like the one Edge is working on won't fix that problem. "Even if we did regenerate the cells with a drug, they would still be defective and would presumably die off because [the person] would still have the same mutation," Edge said. Some researchers are looking into fixing the mutation itself through gene therapy. In experiments, the altered gene is delivered to the relevant cells using a modified virus. That sounds simple enough, but the reality is much more complicated — there are hundreds of genetic mutations that can cause deafness, so researchers have to make sure they're targeting the right ones and that they're doing it in the right cells. The researchers are still figuring out exactly when this kind of therapy would be the most effective (it would likely be at a very young age, as the cochlea degenerates over time in people with hereditary hearing loss). 

Several researchers, including Moser's group, have already been able to dramatically restore hearing in deaf mice over a period of several months. But Moser said that because there are so many genes that can cause hearing loss, any specific gene therapy may only be applicable to a small percentage of cases. In order to use gene therapy to make a big dent in the number of hereditary cases, scientists need to have the ability to edit hundreds of genes. That's not possible with much specificity yet, Moser said.

All these advances can drastically improve the quality of people's lives, but quick fixes for hearing loss are not coming soon, in Heller's estimation. "I don't think there's something on the horizon, whether it's a technological device or a drug, that will provide an immediate cure," he said. Indeed, nearly all the researchers stressed that most of these technologies will not be available to the general public anytime soon. They said press coverage typically leads to dozens of letters from patients volunteering for research into these techniques, and they usually have to tell people in search of hearing help that the techniques are not yet ready.

Heller expects that progress will be step-by-step. First, diagnostics will greatly improve over the next few decades, followed by breakthroughs in hearing aids and cochlear implants, drugs and maybe gene therapy. It's not clear which will come first, and it could take as long as 100 years, but chances are, the deaf and hard of hearing will have many more options than they do now.

"It's an exciting time to be working on hearing restoration," Moser said.

April 2017 KSHB Kansas City

Layla Walker's piano playing is music to her family's ears, but not to hers. "Today I am going to get my cochlear implant turned on," she said. "It's going to be super cool. And guess what - I'll be able to hear everything, even birds singing. I've never heard birds singing before.” Layla is blind and mostly deaf. The 16-year-old has lived the majority of her young life in total darkness and silence.

"When I think of certain colours, I think of the thing it relates to," Layla explained. "Like blue, I think of ocean and red, I think of a heart. Not being able to hear, it's most difficult for me because I can't hear where in the world noises are coming from.” But that changed when her audiologist activated her cochlear implant. 

"There is a really big advantage that comes with connecting with your world via sound," explained Jamie Governal with St. Luke's Hospital's Midwest Ear Institute. "For Layla, it's even more important because of her vision loss. It's really awesome for kids to be able to hear their parents voices, hear birds chirping, all those things we take advantage of day-to-day.” But as cool as it is, the cochlear implant goes beyond helping Layla hear a bird's song; it is a stepping stone to her independence. "When she can cross a certain level of independence, she can have a guide dog, so that way she can have the ability to have even more independence," explained Layla's dad Jason.  And while she has big dreams, for today, Layla wants to enjoy the simple things.

"I am going to try to talk to my parents and my siblings and maybe try to play the piano, and see what that sounds like," said Layla.

April 2017 Starts at 60

A video of a baby boy hearing his mother and father speak for the first time has been warming hearts around the world. Lachlan was diagnosed at birth with moderate-to-severe hearing loss in both ears and was just seven weeks old when he was fitted with hearing aids on each ear by Australian Hearing.  His parents say they cried tears of happiness when his hearing aids were switched on and they saw his face light up at the sounds around him. The magical video of Lachlan been viewed over 4 million times since it was uploaded to the internet in 2014, and continues to be viewed today.  It’s one of many online videos showing people hearing for the first time or recovering their hearing, and they almost always end in tears of happiness. 

LachlanAustralian Hearing audiologist Emma Scanlan has been present at many moments like the moving ones caught on video. She says witnessing babies like Lachlan hear for the first time, or seeing an adult patient hear again after years of silence, is always emotional. “We’re all crying by the end of it,” she says. “I’ve seen both children and adults hearing for the first time or hearing again after a very long time of really struggling to hear. They’re a bit shocked at first generally. You can see they start to smile especially when it’s the parents there in front of them and they then associate that sound with the parents very quickly and it becomes a very joyful experience.”

But many Aussies are waiting too long for their own moment like this. Hearing loss affects one in six Australians, ranging from sensorineural hearing loss – often caused by ageing – to conductive hearing loss, which can be caused by a blockage in the ear or damage to the hairs in the inner ear.

However, on average, Australians put off getting their hearing tested seven years after they first start to notice changes. Scanlan says Australian Hearing is working to close the gap here because so many people are living with hearing difficulties instead of addressing the issue. “The people that do the best are the people who act immediately,” she explains. “Our hearing naturally declines with age because the hairs protecting the inner ear start to deteriorate.” The inner ear is filled with tens of thousands of little hairs and through repeated use or through battering from noise as we get older, these hairs lose their elasticity and don’t work quite as well as they used to,” Scanlan says.

She said hearing aids, cochlear implants or a combination of both are all popular options for those dealing with complete deafness or hearing loss.

March 2017 Science Daily

Cochlear implants provide many deaf people with a significantly improved ability for oral understanding and a considerable boost to their quality of life. However, despite the technological advances, there are still some 5 to 10% of adult patients for whom this technique remains stubbornly ineffective. Why? In order to find an answer to this question crucial for clinical practice, Diane Lazard, an ear, nose and throat surgeon at the Institut Vernes (Paris) and Anne-Lise Giraud, neuroscientist in the UNIGE's Faculty of Medicine, have sought to identify which brain factors might be linked to the success or failure of implants. The two scientists have studied how the brain of a deaf person manages to represent the sound of the spoken word and its capacity of re-using these representations after a cochlear implant.  Giraud explained: 'The test went like this. We presented some visual stimuli to the subjects, in the form of written word, and asked them to determine whether two words, without the same orthographic ending, rhymed or not -- for instance wait and gate. Subjects would then have to recourse to their memory of sounds and, using functional neuroimaging (fMRI) techniques,  we observed the neural networks in action.' 

brains

 Top: red shows right occipito-temporal coupling during deafness, indicating a poor cochlear implant prognosis. Below: blue shows right occipito-tempora uncoupling after deafness, indicating a good cochlear implant outcome

Whereas the researchers were expecting that the subjects would be slower and less accurate that those in a control group of people without any hearing difficulty, to their surprise they found that certain deaf people completed the task quicker and more accurately than their normal-hearing counterparts.  For these 'Super-readers', who appear to be able to handle written words quicker than those with no hearing impediment, the brain has opted to replace orality by written exchanges and has restructured itself accordingly. The brain circuits used by such 'super-readers', situated in the right hemisphere, are organised differently and cochlear implants actually give poor results. The other deaf people, those who carried out the task at the same speed as the control subjects, remain anchored to orality and gained more benefit from cochlear implants. Unlike the 'super-readers', the latter manage to master lip-reading as deafness encroaches, and therefore maintain a central phonological organisation very similar to that of normal-hearing people, which uses the left hemisphere of the brain. There are therefore two categories of subjects whose brain circuits function very differently.

This research points to the essential role played by the interactions between the auditory and visual systems in the success or failure of cochlear implants. Their outcome will indeed depend on this cortical reorganisation. For 'super-readers', the fact of having adapted to deafness by developing certain "supra-natural" visual capabilities constitutes a handicap for the use of implants. Is it possible to go back in time? 'It's difficult to say at the moment,' says Lazard, 'but the idea is also to be able to spot in advance the people who will have a propensity for the written stimulus and to offer them active means for remaining with orality, particularly with auditory prostheses and speech therapy used much earlier than is currently practised.' But as Giraud explains, 'Equally we do not know why certain people quite unconsciously choose one direction rather than the other, but predisposition surely plays a part, because we all learn to integrate auditory and visual information by the time we are three. Certain people manage this better than others and, with deaf people, those who integrate the audio-visual elements best will probably have a tendency to remain more aligned with orality.' Such results also explain why it is so important to be able to equip congenitally-deaf children during their first few months, i.e. before the onset of the reorganisation of the visual and auditory brain circuits, a process which may compromise their ability to access orality.