Hearing Loss Tomorrow

Hearing loss, unfortunately, is only expected to increase in coming decades as the U.S. population ages. The costs are enormous; economists estimate that each case of hearing loss will result in overall expenses of $43,000 in people older than 60, $453,000 in working-age adults, and more than $1 million in children younger than 3.

Although almost 95 percent of Americans with hearing loss could have their hearing treated with hearing aids, many cannot or do not take advantage of these devices.

But with continued funding from the National Institutes of Health and other organizations, brain scientists can engineer more accurate and economical hearing implants, develop better methods for detecting and preventing hearing loss, and find ways to replace lost hair cells.

Many hearing aid users complain that, despite their expense, the devices do not help them understand speech well or prove useful in noisy settings. Researchers are working on devices that selectively amplify certain frequencies to minimize these issues.

Cochlear implants also are quite expensive; each device is estimated to cost around $60,000 per person. Using only about 22 electrodes, they also provide an imperfect form of hearing. But neuroscientists are working on new versions that may use as many as 50 electrodes and cost less.

New types of implantable devices also are in the works. Brain researchers are experimenting with nanotechnology to build smaller, faster, more efficient implants and sound processors. Neuroscientists also have discovered methods of using light, instead of electrodes, to directly stimulate auditory neurons. Work continues on implants placed directly into inner brain regions and other methods to activate the auditory nerve.

Other research is looking at better ways to diagnose and prevent hearing loss. Scientists have detected many genes that underlie inherited forms of deafness. Such discoveries may provide new genetic screening tests for families with inherited forms of hearing loss, allowing for family planning decisions as well as for earlier instruction and treatment for affected children. With increased understanding of genetic defects, scientists will be able to craft personalized treatments. For instance, cochlear implants work well for some forms of inherited hearing loss but not for others. In addition, public outreach on the dangers of loud sounds could prevent many cases of hearing loss entirely.

Some scientists are looking for a way to "cure" hearing loss by restoring lost hair cells and countering age-related changes in the ear and brain. Early work has begun using stem cells and gene therapy; researchers have found ways to convert rodent stem cells into hair cells and have used gene therapy to induce the formation of new, functional cochlear hair cells in mice. Other research is centered on natural hair cell replacement seen in certain animals and drugs that might stimulate hair cell growth.

Hope for Other Diseases

Even though millions of people stand to gain from studies of hearing loss, the benefits don’t end there. Such work also may benefit other common and crippling neurological disorders, including autism and dyslexia, that feature similar disruptions in the ability to understand, empathize, or communicate.