Eustachian tube function testing
Eustachian tube function (ETF) was measured by Tubomanometer (Spiggle&Theis, Medizintechnik). An extended test of Eustachian Tube Score (ETS-7) was used which combines subjective (clicking sound when swallowing, Valsalva) and objective (tubomanometry, tympanometry) measures of ETF (Supplemental table2). The total score of ETS-7 is 10 points and ETS-7≤7 would be diagnosed as ETD.