TICA Implantable Hearing Aid
IMPLEX AG Hearing Technology of Germany has developed a fully implantable hearing aid, which they call the TICA. The first implantation was performed in December 1999, following European approval of the device.
In a normal ear, sound waves enter the ear canal and vibrate the eardrum, which in turn vibrates the three hearing bones (hammer, anvil, and stirrup). The vibrating bones stimulate the cochlea, which is a fluid-filled sack that contains “hair cells”. The cochlear stimulation causes the fluid to move, which moves the hair cells. The moving hair cells cause electrical signals to be sent to the brain over the auditory nerve.
A conventional hearing aid augments this process by amplifying the sound before it is sent to the eardrum. The microphone picks up the sound and converts it to an electrical signal, which is amplified by the hearing aid electronics. The amplified signal is then converted back to sound by a loudspeaker, and the amplified sound energy drives the eardrum.
The front end of the TICA device is the same as a conventional hearing aid. A loudspeaker detects the sound and converts it to an electrical signal, which is amplified by the hearing aid electronics. Unlike a conventional hearing aid, however, the TICA has no loudspeaker. Instead, it uses the amplified electrical signal to drive the hearing bones directly, which IMPLEX says results in increased fidelity.
IMPLEX claims the following advantages for their device:
1. Improved speech intelligibility due to a wider range of undistorted frequency and a reduction in noise.
2. The ear canal remains open so that one’s own voice sounds natural; also ear mold problems and moisture problems are avoided.
3. A greater freedom in physical activities and sports, including the ability to participate in water sports with the hearing aid in place.
The TICA operates for about 60 hours on a full charge. It is recharged in about 90 minutes using a headphone-like device attached to a charger. It comes with a remote control, which can control the hearing aid characteristics, and switches among four different programs. It costs about $22,000, and is currently available only in Europe. The TICA is recommended for moderate to severe hearing losses.