How to perform the Short Increment Sensitivity Index (SISI) test with Equinox Evo

12 March 2025

10 mins

Reading

Required equipment

Equinox Evo
A patient response button
Headphones or insert phones

Test procedure

In addition to the ordinary controls for channels 1 and 2 and the audiograms, there is a table that shows the SISI percentage for the right and left ears for individual frequencies. — **Figure 1:** SISI test screen.

Open the AC440 and enter the SISI screen by selecting Menu | Tests | SISI.

Select Tone or Warble Tone in the channel 1 input list. If needed, masking can be selected in the channel 2 input dropdown list.

Select headphones or inserts on the channel 1 / channel 2 output lists.

Set the input level to 20 dB above threshold using the dB HL Decrease/Increase channel 1/channel 2 buttons or arrow keys on the PC keyboard.

Explain to the patient that they will now hear a series of tones. If suddenly one tone seems louder than the other tones, the response button should be pushed immediately.

Select the preferred type of SISI test. Setting the system to 1 dB increments is the classical SISI. If the patient can hear these increments and scores high, cochlear damage is likely. You may also choose 0 dB, 2 dB, or 5 dB increments.

If the patient does not manage to get a high score on the SISI test, this could be indicative of retro-cochlear damage.

Start the test by pressing START on the PC or by pressing the play icon on the Touch Keyboard.

During the testing, the frequency and intensity can be adjusted manually.

The system will automatically count the number of reactions from the patient. Note that the system needs 20 presentations to calculate a SISI score.

Repeat the test for all desired test frequencies.

Press STOP to end the test.