Sonotubometric measurement of the eustachian tube function by means of band noise. A clinical view of the acoustic measurement of the eustachian tube.

The Eustachian tube is well known as an organ serving the ventilation and drainage of the tympanic cavity and mastoid. Ventilation is carried out by the opening and closing of the Eustachian tube accompanying swallowing movements. Until now there has been no instrument to quantify these motor activities of the tube necessary for its function as a ventilator. The author developed a generally applicable sonotubometer Model WIO-01 with the help of Siemens Hearing Institute K.K. for automatic measurement of the aforesaid tubal function with the use of 7 kHz full-octave band noise. In a sonotubometric trial with 32 adult female subjects, the duration of patency of the Eustachian tube was 288.5 +/- 1.38.5 ms, and the amplitude eliciting response was 16.4 +/- 8.3 dB. The positive response rate was 89.1%. In 89 children aged 4-12 years, a positive response was detected in 117 ears (61.9%). The mean duration of patency was 337.7 +/- 154.4 ms, and the amplitude 16.3 +/- 7.2 dB. It is physiological to have tubal opening and closing during natural swallowing. It is therefore important to understand the tubal function when dealing with tympanoplasty and diseases caused by tubal dysfunction.