When we talk about treatment of hearing loss in children or adults, we most likely first think of hearing aids, but there are different types of children’s hearing devices, and other options available for deaf children. This page looks at some of the technologies available to treat children’s hearing loss and how they differ.
Hearing aids use a microphone to pick up sound, which can then be amplified by the processor to different volumes for different frequencies, according to the type of hearing loss. The amplified sound is passed down a tube, into the ear canal through a specially fitting earmould that is inserted into the ear. Children’s hearing aids also have a feature where volume is decreased on detection of particularly loud sounds, potentially giving protection from further hearing loss.
The mechanical ‘sound processing’ section of a hearing aid is worn behind the ear. This is attached by a small, thin tube to an earmould that is inserted into the ear. Children’s earmoulds for hearing aids will need to be replaced regularly (usually initially every three months) as your child grows. As children have small ears and move around a lot, you may also face initial problems in keeping the BTE section of the hearing aid from flapping around, or falling down. Retainers, toupee tape and other options are available to help with this.
Cochlear implants are usually required for unaided hearing loss thresholds 90 decibels and below. Unlike hearing aids which simply amplify sound, a cochlear implant bypasses damaged or dead hair cells in the inner ear and passes an electrical current, directly stimulating the auditory nerve. The electrodes are linked to both a transmitter worn on the outside of the head and to a sound processor worn behind the ear. Sounds are picked up by a microphone contained in the sound processor. Here, they are turned into electrical signals which contain information, much like a digital code for sound. These electrical signals are then passed onto the transmitter which is implanted in the skull, down to the implant. The implant then decodes these electrical signals and passes the appropriate amount of electrical current to the hearing nerve via an electrode array. The amount of current determines the loudness of the sound, and the position of the electrodes determines the pitch. The hearing nerve is effectively stimulated by the electrodes and the signal is sent to the brain, where it can be interpreted as sound.
A cochlear implant consists of a transmitter and electrodes that are inserted inside the skull as well as a behind the ear sound processor. The transmitter has a wire with electrodes that pass into the cochlea. There are magnets to essentially keep it in place, so it is aligned properly with the sound processor and works correctly. Much like hearing aids, the BTE section of a cochlear implant can move around so toupee tape, retainers or other accessories can help with this.
BAHAs (bone anchored hearing aids) amplify sounds much like a hearing aid but rather than playing back sound through an earmould inserted into the ear, the sound is picked up by an abutment (sound processor) that is attached behind the ear and sounds are amplified via a vibrating pad behind the ear rather than through an earmould inserted into the ear canals. BAHAs are used when there is permanent conductive hearing loss, meaning hearing aids would be unsuitable, as the sound would be able to make it effectively through ear canal to the middle and inner ear. Like hearing aids, they can be set to amplify different frequencies by specified amounts and to decrease volume of very loud sounds to protect hearing.
Fitting of BAHAs requires surgery as the sound processor is fitted behind the ear using a titanium screw which is implanted into the skull. This surgery is not usually performed before the age of four. Children younger than this will use a softband to keep the sound processor in place.