The purpose of this paper is to observe the difference in hearing ability between normal hearing and impaired hearing for the parameters of AI, and to know the effects of frequency characteristic of masking noise on syllable perception . This study includes the articulation tests and determines AI of the experiment sound fields by varying its parameters. The results of articulation test indicate that the effect of S/N on speech discrimination is different in each octave band noise, and the difference of articulation score between normal hearing and impaired hearing becomes larger in 0.5 or 1 [kHz] band. As a result of considering hearing loss in AI calculation, it is able to reflect hearing ability by optimizing its parameters. And considering syllable appearance in sentences, it is limited to the use of syllables of highest impact.
