2011 Volume 51 Issue 3 Pages 2-11
The authors made a demonstration model to explain the amplification of sound by the area ratio of tympanic membrane vs round window, and studied the effect of the use of this model for the understanding of students in the class at a medical vocational school. The model was made using a mechanical cooking scale with a styrene disk and a commercially available toy air-gun. For the purpose of generating the force, the proper size of the styrene disk, the proper distance between styrene disk and the air-gun and the proper caliber of the air-gun were examined. Furthermore, the comparison was made between the toy air-gun and a self-made air-gun in generating the force. From the result of the examination, 20 cm and 5cm for the diameter of tympanic membrane and for that of round window, 40 cm for the distance from the air-gun to the disk, and 12 cm for the caliber of air-gun were selected. Demonstration using the commercially available toy air-gun was conducted with the above described condition. After the lecture, the question " where is the sound amplified in the human auditory system?" was asked to the students. The ratio of the students who answered correctly, " it is in the ossicle" increased significantly compared to the ratio of the correct answers given before the lecture. However, there was no difference in the result with or without the use of this model. To the question "how does the auditory system amplify the sound?" the ratio of the students who answered correctly, " it is amplified by the work of the lever" increased compared to the ratio of the correct answers before the lecture. Although when the model was not used in the lecture, no students answered " the area ratio of the tympanic membrane vs the round window", with the use of the model, the ratio of students who answered correctly increased significantly. The authors assumed that the use of this model has contributed to students' better understanding of the amplification of the sound by "lever action" as well as the understanding of "the area ratio of the tympanic membrane vs the round window".
