Short Increment Sensitivity Index (SISI) is an audiometric test that evaluates a person's ability to detect small changes in the intensity (loudness) of a pure tone.
The primary objective of the SISI test is to determine the individual's sensitivity to slight increases in the intensity of a pure tone at a specific frequency.
During the SISI test, the individual wears headphones and listens to a pure tone at a constant frequency. Short increments (typically 1 dB) of intensity are added to the tone, and the person indicates whether they can detect the changes.
The results of the SISI test are not typically plotted on a standard audiogram. Instead, they provide information about the person's ability to detect small changes in intensity.
SISI is often performed at a frequency of 1,000 Hz, and the intensity increments are added for a short duration (usually 0.5 seconds).
SISI is used primarily in the evaluation of retro cochlear pathology, which involves issues beyond the cochlea, such as the auditory nerve or central auditory pathways.
It is not typically used as a routine hearing assessment but may be employed in special cases where retro cochlear pathology is suspected.