short increment sensitivity index test

short in·cre·ment sen·si·tiv·i·ty in·dex test (SISI test),

the presentation of a tone 20 dB above threshold, followed by a series of 200-millisecond tones 1 dB louder; the percentage of small increments detected by the subject is the small increment sensitivity index. In sensory hearing losses, it will be high, and in normal hearing and neural hearing losses, it will be low. Perception of these increments indicates cochlear damage.