You may find that your outer ear and ear canal is itchy or swollen. This could be a result of an allergic skin reaction.
Most allergies are likely to affect your middle ear. The Eustachian tube is located in this part of your ear and serves as a drainage tube, similar to a pressure release valve. If the tube is clogged with mucus, and pressure builds in your ear it can make it difficult for you to hear. These are the symptoms of a conductive hearing loss, and the problem is usually temporary. You should find that it resolves itself as the allergic reaction fades.
If you experience Ménière’s disease and allergies, you may find that changes in your hearing are more prevalent when your allergies are at their worst.
You can learn more about the parts of your ear and how they process sound here.