The development of impedance audiometry during the past two decades has added new scope and dimension to clinical audiology. Based on the pioneering effort of Metz, subsequent workers have refined instrumentation, technique and interpretation to produce an invaluable tool for differential diagnosis. This paper described measurement carried out with using a DANAC-40 Impedance Audiometer on normal population of 682 persons(1364 ears) ranging in age from 3 to 80 years of age. The results were as follows : 1) Using Jerger's classification, tympanogram were found 1277 ears(93.6%) in type A, 1 ear(0.1%) in type B and 86 ears(6.3%) in type C. 2) Mean middle ear pressure at maximum compliance was -12.6±22.5mmH₂0(mean±SD). 3) The mean static compliance in type A tympanogram was 0.55±0.38cc, male 0.59±0.40cc, female 0.49±0.33cc, right 0.54±0.36cc, left 0.55±0.40cc. There was significant difference between male and female(p<0.01). 4) The mean base(external auditory canal volume) was 1.02±0.35cc, male 1.08±0.40cc, female 0.95±0.28cc, right 1.01±0.33cc, left 1.03±0.37cc. There was significant difference between male and female(p<0.01). 5) The incidence of ipsilateral reflex present in 1000Hz was 45.7% in 80dB, 53.0% in 90dB, 82.2% in 100dB, 94.5% in 110dB and contralateral reflex was 31.7% in 80dB, 38.3% in 90dB, 70.8% in 100dB, 87.4% in 110dB. The incidence of stapedial reflex absent in 1000Hz was 70 ears(5.5%) in ipsilateral reflex and 161 ears(12.5%) in contralateral reflex.