Pure tone audiometry was done before and after loading the pure tone of 2KHz at 100dB(A.S.A.) for 15 minutes on the twelve patients having unilateral O.M.P.C. Speech discrimination score was measured in five cases among the twelve. And the following results were obtained. 1. At the frequencies of 2,3 and 4KHz, the normal ears scored greater T.T.S. than the diseased ones. The difference of T.T.S. between the two groups was greatest at 3KHz, measured as 22.5dB from 35.8dB in the normal ears and 13.3dB in the diseased. 2. A little difference was seen between the two groups at the frequencies of 0.5, a and 6KHz and the diseased ears showed greated T.T.S. than the normal. (less than 1.2dB). 3. After the pure tone loading, speech discrimination scores marked a rather increase of 7.2% in the diseased ears and a decrease of 2% in the normal. And at the time, the mean T.T.S. from the Fletcherian pure tone average was 11dB in the normal ears and 10dB in the diseased with a little difference of 1dB.