The development of impedance audiometry during the past decade had added new scope and dimension to clinical audiology. After introduction of the impedance audiometry, the measurement of sound conducting system in combination with the development of otoneurology and microsurgery played an important role in diagnosis of hearing disturbance. Based on the pioneering efforts of Metz (1946), who first introduced the concept of impedance audiometry, Terkildsen and others pioneered the application of the electroacoustic approach, culminating in the present commercially available electroacoustic bridge (Madsen ZO 70, 72). In Korea, still there is no report about this, so we measured the normal value of Korean by using Madsen ZO 70 and afford it as a base of further study in sound conduction system of middle ear. The results are as follows ; 1) The tympanograms in normal and sensori-neural hearing loss cases were mostly in type A curves. 2) The range of acoustic impedances in normal cases were 621Ω to 4320Ω (mean. 1972Ω), and the range of static compliances in normal cases were 0.2 cc to 1.4 cc (mean. 0.69 cc). 3) Stapedial reflex thresholds were 96 dB at 500 Hz, 97 dB at 1,000 Hz, 99 dB at 2,000 Hz, and 96 dB at 4,000 Hz in normal and sensori-neural hearing loss cases in mild and moderate degrees. S.R was mostly absent in sensorineural hearing loss cases in severe degree.