Monocles are not that common nowadays and for good reason. If both your eyes were far-sighted, you wouldn't even consider a monocle. Just as nature intended, seeing with two eyes allows for depth perception... and the same applies to hearing. Binaural hearing, that is, hearing with both ears, may mean the difference between just hearing and hearing and understanding.
The physical position of our ears on either side of our head allows us to hear and localise different sounds. Due to the distance between our ears, sound reaches each ear at a slightly different moment in time and with a different intensity, enabling our brain to determine depth and direction of the sound. Localisation is critical for safety, especially in traffic.
Improved hearing in noise using binaural hearing is termed the 'squelch' effect. With two ears, the brain is better able to focus on and process sounds that you want to hear (speech) while 'squelching' (ignoring) sounds that you don't want to hear (usually background noise). With one hearing aid, the brain cannot do this very well - it needs to compare and contrast timing, pitch and intensity cues of sounds from both ears to make sense of it. Binaural listening can result in a signal to noise advantage of 3 dB.
A sound presented to both ears is judged to be louder than the same sound, at the same intensity, presented to one ear only. This means that a user of two hearing aids can set the volume of each one lower, resulting in more pleasant hearing and less amplification of distracting background noises.
Wearing two hearing aids gives the maximum opportunity to respond accurately and confidently, whether conversation comes form the left or right side. Wearing two aids also stops the feeling of a 'poorer ear' as our head causes a shadow, known as 'head shadow effect'.
Users of two hearing aids report many additional benefits, including more natural sound quality, a relaxation of listening effort and improved ability to hear correctly and respond appropriately.