Yes, If you have two ears with hearing loss, and if hearing in both ears could be improved from hearing aids, you will need two hearing aids.
A hearing aid worn in only one ear will often sound "flat" & "dull". Binaural amplification -- aids on both sides -- minimizes impact of "head shadow" drop off, improves sound localization and widens dynamic range.
Binaural hearing allows a quality of "spaciousness" or "high fidelity" to sounds, which cannot occur with monaural (one ear) listening. Understanding speech clearly, particularly in challenging and noisy situations is much easier while using both ears. Additionally, using two hearing aids allows people to speak to you from either side of your head.
Lastly, most people simply cannot hear well using only one ear. There are studies in the research literature that show that children with one normal ear and one ''deaf'' ear are ten times more likely to repeat a grade as compared to children with two normally hearing ears. Additionally, we know that if you have two ears with hearing impairment, and you wear only one hearing aid, the unaided ear is likely to lose word recognition ability more quickly than the ear wearing the hearing aid.
