Bionic Ears: Can They Restore Hearing?

The definition of bionic describes artificial body parts that work like real ones. Since the 1950s, the cochlear implant has become synonymous with hearing improvement and improved quality of life in those people with severe-to-profound sensorineural hearing loss. More recently, there has been the development of additional electronic devices that allow a person to attain hearing when medical or surgical methods or traditional hearing aids fail to restore hearing sufficiently. In a sense, these are novel, innovative types of bionic hearing technology.

Hearing loss explained

There is an unusual way in which we describe human hearing. We refer to a hearing threshold of zero decibels as the softest sound an average person can hear.

Most people know the term decibel. Still, only some understand that a decibel is really a unit for expressing the ratio between two physical quantities, acoustic and electric power. That measurement is logarithmic, meaning it is expressed in factors of 10.

Hearing loss is classified into the following categories:

• Mild. A loss of 26 to 40 dB, meaning the person can hear some speech but not soft sounds.
• Moderate. A loss of 41 to 55 dB — cannot hear normal speech.
• Severe. 71 to 90 dB — can hear only some loud sounds.
• Profound. Above 90 dB — can only hear a sound if it is very loud.

Diagnosing hearing loss and deciding on clinical treatment and management is an individualized process. Some patients undergo medical workups to rule out metabolic, infectious, or autoimmune causes.

Disabling hearing loss affects over 430 million people, according to the World Health Organization. It is estimated that by 2050, nearly 2.5 billion people are projected to have some type of hearing loss, and at least 700 million will require some form of hearing rehabilitation.

Some people with various levels of hearing loss may undergo surgery or use traditional hearing aids. Patients who fail all of the measures still may have options for restoring hearing. These range from cochlear implants to newer electronic devices.

Cochlear implants

Cochlear implants are designed with a microphone, a speech processor, a transmitter, and an electrode array. A cochlear implant helps provide a sense of sound to a profoundly deaf person but does not restore normal hearing.

A cochlear implant works by bypassing damaged or non-functional portions of the ear and directly stimulating the hearing or auditory nerve. It is much different from a hearing aid that amplifies sounds so the person can hear them more easily.

Cochlear implants were first designed in 1957 as single-channel devices. Multichannel devices were introduced in 1984. There are three FDA-approved devices available in the United States today, including:

• Nucleus 5 cochlear implant system (Cochlear Corporation);
• Clarion HiRes 90K (Advanced Bionics Corporation);
• Synchrony device (MED-ELCorporation).

The clinical conditions that lead to being a candidate for a cochlear implant include:

• Congenital hearing loss and prelingual deafness;
• Acquired hearing loss and postlingual deafness;
• Severe hearing loss that can be aided and that deteriorates to profound loss in childhood, adolescence, or adulthood (perilingual) and coexists with various degrees of language development.

Cochlear implants have a high success rate and a low rate of complications. The device, surgery, and postoperative training can easily exceed $100,000. Private insurance plans and Medicare typically cover most cochlear implant costs.

BAHA implants

Bone-anchored hearing aids (BAHA) implants are designed for patients with single-sided deafness and conductive or mixed hearing loss. Therefore, BAHA implants capture sound from the environment using an external sound processor and then translate that sound into vibrations sent to the skull's bone.

The device is made of titanium. It is inserted into the bone and is highly reliable for long-term clinical use with proven reliability.

The BAHA implant is a great choice for patients who have an intact cochlea or inner ear but there is damage to the outer or middle ear structures.

Vibrant Soundbridge

This is a middle ear implant that was first developed in 2000 and given FDA approval. The Soundbridge device is a unique, implantable device. It mechanically vibrates the tiny bones in the middle ear behind the eardrum to reproduce sound.

The Vibrant Soundbridge has an external microphone, sound processor and amplifier, and audio processor. The hearing results are similar to the BAHA in select patients. It does require the patient to wear a device like a hearing aid and recharge or change the battery.

Electric acoustic stimulation

Electric Acoustic Stimulation (EAS) is a combination of the best features of cochlear implants and hearing aids. It is a wearable device, and no surgery is required.

The EAS device is a breakthrough for people with high-frequency hearing loss. It allows for improved conversation, enjoying TV or music, and much more.

Auditory brainstem implant

The auditory brainstem implant (ABI) is another alternative to replacing hearing when the person is not able to use a hearing aid and is not a good candidate for a cochlear implant.

Auditory brainstem implant was originally designed for patients with a rare genetic disorder called neurofibromatosis type 2, where there is nerve damage caused by benign tumors. It can now be used for other causes of nerve loss.

Auditory brainstem implants directly stimulate the brainstem. It is similar to cochlear implants since the hearing results are not a full range of hearing.

There is more of a perception of sounds in the environment, and there is a great deal of postoperative training that is required.

The technology we consider bionic when it comes to replacing our senses is similar to hearing and vision at the current time, except there are more choices with hearing. Most people are familiar with cochlear implants as a replacement for complete hearing loss. These devices are implanted below the skin, and they require intensive postoperative patient training to work properly. Cochlear implants provide the perception of sound too successful wearers, but hearing is still not what most people would consider normal.

Newer electronic technology has provided patients with specific types of hearing loss with more choices other than cochlear implants. These newer devices also provide sound perception rather than normal hearing, but some of them, like the electric acoustic stimulation (EAS) device, do not require surgery.

Check with your hearing healthcare provider to find out what may be the best option for you or your family member who has profound hearing loss in at least one ear.