Effects of practice on SISI scores and the relationship of SISI score to the intensity difference limen.

The standard short increment sensitivity index (SISI) was given to 24 normal hearing subjects 10 times in two test sessions. For each subject the intensity difference limen was determined with a quantal method using the SISI apparatus. Although the group data indicated a statistically significant improvement in scores across presentations, the change was not clinically significant, in that the highest mean score continued to be "negative" in clinical interpretation. Four individual subjects, however, moved from initial sntations. Highest scores achieved by the subjects were found to be significantly related to intensity difference limen. The results suggest that the clinician must be aware of a potential for a clinically significant improvement in SISI score with practice on the part of some subjects.