Is it really necessary to wear two
hearing aids, or can I get by with just one?
There are four main reasons why
binaural (two eared) listening is superior to monaural (one eared) listening.
They are:
Better Hearing in Noise: An individual's hearing in noise can be improved if the
signal reaching each ear arrives at a slightly different moment in time. This
is technically referred to as phase. When the brain receives slightly
different, yet still audible signals at the two ears, it has the ability to
cross-correlate and process the primary signal (usually speech) better than if
the signal is received monaurally.
Improved Signal versus Noise Level
from Optimizing Position: Sound
loses intensity (loudness) when it travels across the head. This occurs mostly
for the high frequencies which are the most important for understanding of
consonants, such as /s/, /t/, /f/, and /sh/. If you have a hearing aid on only
one ear, say the left one, and the person you wish to hear is speaking to you from
the right side, the consonants may be decreased by nearly 20 decibels by the
time it gets to your aided ear. Unfortunately, noise in the room may occur from
any or all directions, so while the noise level is not decreased, the speech
level is. Wearing two hearing aids ensures that the speech sounds will not be
diminished any more than necessary because of your position in the room.
Improved Localization Ability: We determine where a sound is coming from on the basis of
1) the relative time in which the sound arrives at each ear, 2) the relative
difference in loudness at the two ears, and 3) the relative difference in the
pitch of the sound at the two ears. When there is a large difference in hearing
between two ears (as might occur when a person with similar hearing in both
ears only wears one hearing aid) the brain cannot make use of these subtle
relative differences and their ability to locate sounds may suffer.
Possible Deterioration of the
Unaided Ear:We hear in our brain, not in our
ears. The ultimate goal of hearing aids is not just to send sound into the ear.
It is also essential to retrain the central auditory system in the brain. While
it is uncertain whether hearing sensitivity (ability to hear soft sounds) will
decrease if your ear is not stimulated adequately, research now suggests that
there can be changes in the way in which your brain processes sound when it is
"starved." Thus, providing stimulation may be important in preserving
your auditory potential.