The meaning of dysfuntion of eustachian tube?

dys·func·tion
ˌdisˈfəNG(k)SH(ə)n/
noun
noun: dysfunction; plural noun: dysfunctions

abnormality or impairment in the function of a specified bodily organ or system.
"bowel dysfunction"
deviation from the norms of social behavior in a way regarded as bad.
"inner-city dysfunction"
google.com

Eu·sta·chian tube
yo͞oˈstāSH(ē)ən ˌt(y)o͞ob/
nounAnatomy
noun: Eustachian tube; plural noun: Eustachian tubes

a narrow passage leading from the pharynx to the cavity of the middle ear, permitting the equalization of pressure on each side of the eardrum.
google.com