(This is the second of two columns on hearing aids.)

About one in three Americans over 60 suffers from loss of hearing, which can range from the inability to hear certain voices to deafness. However, only about one out of five people who would benefit from a hearing aid uses one.

Hearing aids have a microphone, amplifier, and speaker. Sound is received by the microphone, which converts the sound waves to electrical signals and sends them to an amplifier. The amplifier boosts the signals and then sends them to the ear through a speaker.