The classical method for the measurement of sensori-neural hearing loss, bone conduction audiometry, presents serious problems both at the clinical and theoretical levels. So, Rainville had attempted to improve these problems by approaching the measurement of sensori-neural loss with an entirely new procedure. And then, Jerger and Tillman reported a modification of Rainville's technique in which thermal noise of fixed intensity was presented to the skull through a standard bone-conduction oscillator mounted at the center of the forehead. And the amount by which this noise shifted the pure-tone air conduction threshold in a particular patient was compared with the shift had been produced by the same noise level in normal ears in order to determine the degree to which the patient's sensori-neural mechanism was impaired and the index, so computed, was called the sensori-neural acuity level(SAL). They had been proved that the result was more valid and accurate than the conventional bone-conduction audiometry. Jerger and Tillman had been used Grason-Stadler, Model 901, as a thermal noise generator, however Robert C. Cody has been proved that the result was same as in using the Grason-Stadler, Model 162, speech audiometer as a white noise source, in 1966. We, hereby, report the result of our study of SAL in normal hearers, conductives and sensori-neural hearing losses measured by Beltone 15 C audiometer (for obtaining pure-tone threshold measurement) and Grason-Stadler, Model 162, speech audiometer for noise source.