Two aids provide a more natural perception of sound perhaps for the following reasons;
Hearing in Ambient Noise: With the brain receiving two sound signals it can better separate the background ambient noise from normal conversations. Those fitted with two hearing aids can understand speech better, its quality is improved, and they can keep up with normal conversations.
Sound Location: Sound is located by the brain through differences in the way sound is perceived by each ear. A study in Sweden with 190 people between ages 18 to 95, all with two hearing aids, found 60 percent heard better with two hearing aids. In this study one-third reported two aids gave them more of a stereo effect and one in five found that two aids improved their ability to judge the direction of sound.
Additive Effect: Studies have shown that two hearing aids increase the loudness of sound by more than one. In one test researchers found that one hearing aid improved the ability to understand words by 13 percent while two hearing aids increased it to 18 percent. Two aids improve the ability to hear soft sound and distant speech.
Reduced Hearing Loss: Over time hearing loss generally increases taking its
normal course.
Research has shown, however that when only one hearing aid is used, the loss or deterioration rate in the other (unaided) ear, is likely to be greater over a given period of time.
It should be noted that two hearing aids should not be considered where one ear has either normal or no hearing at all.
