Glue ear is a condition where the middle ear becomes filled with fluid which resembles glue in its consistency. 

It is most common in children, and affects approximately one in five children around the age of two, though adults can also develop the condition.  

Glue ear affects your hearing because the fluid that builds up dulls the vibrations that are created by the eardrum and the ear bones as a result of sound waves. Because these vibrations are dampened, the middle ear receives muted signals, which affects your hearing.

It can cause loss of hearing in one or both ears and in most cases the symptoms are temporary.  If hearing loss continues for three months or more and is causing significant hearing loss, treatment may be recommended.