Hearing aids are classified as Class II medical devices and should be purchased from a company that holds a Medical Device Operator's License and conducts hearing tests with reference to the following indicators.
Choose a hearing aid with a sound gain greater than or equal to 1/2 to 2/3 of the hearing loss value. For example, a patient with a hearing loss of 80 decibels should choose a hearing aid with a sound gain of 40 to 50 decibels.
The wider the sound frequency range, the better. The normal human ear has a sound frequency range of 20 to 20,000 Hz, and a hearing aid should have a sound frequency range of 300 to 4,000 Hz.
The larger the signal-to-noise ratio, the less noise is produced.
Harmonic distortion should be less than 5 percent; if it is greater than 10 percent, the sound will be distorted.
Finally, choose a hearing aid based on your specific needs; some patients need to amplify sound waves, others need to compensate for frequency loss.
Maintenance and protection against moisture is key.
For patients who have been fitted with hearing aids, the use of maintenance can not be sloppy.
Daily maintenance, moisture is very important, wash your face, take a shower and make sure to remove the hearing aid when it rains.
Hearing aids are often worn, the human body produces ear wax, ear secretions, etc. will affect the service life, must be cleaned frequently.
When the battery power is lower than a certain level, the sound quality will become rough and unstable, and the battery should be replaced immediately to prevent leakage and corrosion.
The components in a hearing aid are connected by very small wires, which are easily broken after an impact, so they need to be protected from shocks.