Hearing Implants

Whispering with cochlear implants

Hearing Implants for DHH

Hearing Implants are needed for a person who is deaf or is hard of hearing, if the hearing loss is severe or there are other complications. Hearing implants need medical intervention - often surgery. Hence, implants can be put only on the advice and under supervision of trained practitioners. This page covers the basic principle of working for the implants and their types, comparison between aids and implants, and information about major hearing implant brands.

Hearing Implants

A hearing implant is a hearing device that is typically implanted into the ear. They are electronic devices that can be surgically placed in the ear to prevent hearing loss and deafness. Hearing implants are implanted in the inner part of the ear of patients that suffer from mild to severe deafness. Hearing loss is generally of two types that are

  • conductive and

  • sensorineural

When hearing aids cannot fulfill the purpose of enabling a person to listen, hearing implants can be used. They are fitted in the person's ear for surgical purposes and comprise an electrode array, transmitter, speech processor, and microphone. The implanted hearing device tends to transform the sound vibrations into signals that can electrically stimulate the nerves. The signals are then sent to the auditory nerve, allowing the person to recognize the sounds and hear them clearly.

Although the implant is not capable of restoring the hearing capabilities, it allows the individual in order to interpret and understand the sounds. The hearing implant devices are effective, widely accepted, and are a long-term solution.

Types of Hearing Implants

There are different types of hearing implants. The one which is most relevant for a person with hearing loss depends on the cause and the type of hearing loss. But in all cases, hearing implants are relevant when a person with a hearing loss would not benefit properly from the sound amplification of hearing aids or for some reason is unable to wear hearing aids.

The common types of hearing implants are:

  • Cochlear Implants (CI Systems): It is a small electronic device that electrically stimulates the cochlear nerve (nerve for hearing). The implant has external and internal parts. The external part sits behind the ear. It picks up sounds with a microphone. It then processes the sound and transmits it to the internal part of the implant.

A CI is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech understanding in both quiet and noisy environments. A CI bypasses acoustic hearing by direct electrical stimulation of the auditory nerve. Through everyday listening and auditory training, cochlear implants allow both children and adults to learn to interpret those signals as speech and sound.

    • Electric Acoustic Stimulation (EAS Systems): It is the use of a hearing aid and a cochlear implant technology together in the same ear. EAS is intended for people with high-frequency hearing loss, who can hear low-pitched sounds but not high-pitched ones. The hearing aid acoustically amplifies low-frequency sounds, while the cochlear implant electrically stimulates the middle- and high-frequency sounds. The inner ear then processes the acoustic and electric stimuli simultaneously, to give the patient the perception of sound. SYNCHRONY 2 is such a device.

  • Bone Conduction Devices: Bone conduction is the conduction of sound to the inner ear primarily through the bones of the skull, allowing the hearer to perceive audio content without blocking the ear canal. Bone conduction transmission occurs constantly as sound waves vibrate bone, specifically the bones in the skull, although it is hard for the average individual to distinguish sound being conveyed through the bone as opposed to the sound being conveyed through the air via the ear canal. Intentional transmission of sound through bone can be used with individuals with normal hearing — as with bone-conduction headphones — or as a treatment option for certain types of hearing impairment. Bone generally conveys lower-frequency sounds better than higher frequency sounds.

There are many different types of bone conduction hearing aids. Most of them work on the same principle and are broadly categorized in two types:

    • Surgical bone conduction devices consist of an internal implant and an external audio processor used to transmit sound. They require surgery in order to implant the device, which is usually done as an outpatient procedure under general anesthetic, however this depends on the device being implanted and the health condition of the patient. Surgical implants are further classified as:

    • Non-surgical devices only consist of the external audio processor. The processor simply vibrates, making both the skin and the bone vibrate, conducting the vibrations through to the cochlea. Non-surgical devices are ideal for children, who may not be old enough for implantation surgery or who have temporary conductive hearing loss caused by glue ear or ear infections. ADHEAR, Baha Start are such a bone conduction system devices.

  • Middle Ear Implants (MEI): It is a hearing device that is surgically implanted into the middle ear. They help people with conductive, sensorineural or mixed hearing loss to hear. Middle ear implants work by improving the conduction of sound vibrations from the middle ear to the inner ear. There are two types of middle ear devices:

    • Active Middle Ear Implants (AMEI) consist of an external audio processor and an internal implant, which actively vibrates the structures of the middle ear.

    • Passive Middle Ear Implants (PMEI) replace damaged or missing parts of the middle ear, creating a bridge between the outer ear and the inner ear, so that sound vibrations can be conducted through the middle ear and on to the cochlea. Unlike AMEIs, PMEIs contain no electronics and are not powered by an external source.

VIBRANT SOUNDBRIDGE is an AMEI device.

  • Auditory Brainstem Implants (ABI): It is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf, due to retrocochlear hearing impairment (due to illness or injury damaging the cochlea or auditory nerve, and so precluding the use of a cochlear implant).

Hearing Aids vis-à-vis Hearing Implants


Criteria

  • Radio Analogy



  • Extent and Type of Hearing Loss


  • Speech Understanding


  • What the Devices Do and How They Do It



  • Timing


  • Surgery Required?

  • Risk


  • Age Limit


  • Cost & Insurance


Hearing Aids

  • All you need is to fine-tune your radio station and turn up the volume.



  • Hearing loss is mild to profound. Your type of hearing loss is either "conductive," meaning it stems from your outer or middle ear, or "sensorineural," meaning it stems from your inner ear or hearing nerve.



  • Excellent to fair/poor -- you are able to understand approximately 50% or more of spoken words during testing.


  • Hearing aids amplify acoustic sound generally and/or by specific frequencies.






  • Generally, it takes approximately two weeks or less for you to adapt to hearing aids.


  • No.


  • Little to none.



  • No upper age limit.



  • $3,400 - $6,000 for a pair. Some insurance plans cover the cost.


Cochlear Implants

  • Your radio receiver is damaged and sounds like static; turning up the volume will only make the static louder. You need a new radio.


  • Hearing loss is moderate to profound. Your type of hearing loss is called "sensorineural," meaning it stems from your inner ear or hearing nerve.



  • Fair to poor -- you are able to understand approximately 50% or less of spoken words during testing.



  • A cochlear implant device allows you to hear in a different way. This is called electrical stimulation. A surgically placed implant bypasses your inner ear. It translates acoustic sound into electrical signals. It sends the signals directly to the hearing nerve and then on to the brain.


  • Generally, it takes approximately 6 to 12+ months for you to adapt to a cochlear implant.


  • Yes -- outpatient surgery under general anesthesia.


  • Low to moderate risk, because of the surgical aspect.



  • No upper age limit.



  • $60,000 - $100,000+ per implant. Most insurance plans cover the majority or all of the cost.

Low-Pitched Sounds—Hearing Aid Technology

  1. Sounds are detected by the microphones of the audio processor.

  2. Low-pitched sounds are made louder & sent via the earmold to the ear

  3. These sounds are processed by the cochlea and sent to the brain.

High-Pitched Sounds—Cochlear Implant Technology

  1. Sounds are detected by the microphones of the audio processor.

  2. High-pitched sounds are sent to the implant as electrical signals.

  3. These sounds are processed by the cochlea and sent to the brain.

Audio Processors and Implant Devices

Audio Processors (MED-EL)

Cochlear Implant Audio Processor

SONNET / SONNET 2 / RONDO / RONDO 2 / RONDO 3 / OPUS 2

EAS Audio Processor

SONNET EAS / SONNET EAS 2

VIBRANT SOUNDBRIDGE & BONEBRIDGE Audio Processor

SAMBA / SAMBA 2

Bone Conduction System

ADHEAR

Implants (MED-EL)

Cochlear Implant

SYNCHRONY 2

Middle Ear Implant

VIBRANT SOUNDBRIDGE

Bone Conduction Implant

BONEBRIDGE

Journey of Sound: NIH video to explain ow sounds make their way from the source to the brain

Cochlear Implants


The cochlea is a spiraled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the oval window) to the apex (the top or center of the spiral). The spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2¾ turns about the modiolus.


The cochlea is filled with a watery liquid, the endolymph, which moves in response to the vibrations coming from the middle ear via the oval window. As the fluid moves, the cochlear partition (basilar membrane and organ of Corti) moves; thousands of hair cells sense the motion via their stereocilia, and convert that motion to electrical signals that are communicated via neurotransmitters to many thousands of nerve cells. These primary auditory neurons transform the signals into electro-chemical impulses known as action potentials, which travel along the auditory nerve to structures in the brainstem for further processing.

Cochlear implants (CI) make it possible for people to hear and understand sounds even if they have damaged hair cells in the inner ear and have a severe or a profound hearing loss.

A cochlear implant is a small electronic device that can provide a sense of sound to people who are deaf or hard-of-hearing.

A cochlear implant is a hearing implant that bypasses the damaged hair cells in the inner ear and transmits signals directly to the brain via the auditory nerve.

How does Cochlear implants work?

Cochlear implants are designed for people with severe-to-profound sensorineural hearing loss. With this type of hearing loss, the hair cells in the inner ear are damaged, and can’t detect sounds properly. A cochlear implant bypasses these damaged hair cells and sends electric signals to the brain, where they are interpreted as sound.

A cochlear implant system has two main components. The externally worn audio processor detects sounds and sends them to the internal implant, which is placed just under the skin behind the ear.

Overall a cochlear implant works in the following way: