Various methods of examining the Eustachian tube function have been proposed: an acoustic method, an impedance method, and a Eustachian tubo-tympano-aerodynamic method. To perform these examinations, equipment that enables the quantitative inspection of the Eustachian tube function is commercially available. On the other hand, a method that uses Eustachian tube inflation is widely used in practice. Eustachian tube inflation works as follows: air is provided from the pharyngeal opening of the Eustachian tube into the Eustachian tube itself, and a doctor uses a rubber tube to listen to the sound of the air passing through the Eustachian tube. The Eustachian tube inflation method is superior to other methods such as the acoustic method in that the diagnosis also constitutes the treatment. However, there are some disadvantages: since the doctor merely performs auscultation, the Eustachian tube inflation sounds are not saved as data, and as the diagnosis depends on the auditory judgment of the doctor, the objectivity is poor. Therefore, in this research, we set out to quantify the Eustachian tube inflation method and improve the objectivity and reliability of the diagnosis; we developed the Eustachian tube inflation sounds recording system.