Section 874.1070 - Short increment sensitivity index (SISI) adapter(a)Identification. A short increment sensitivity index (SISI) adapter is a device used with an audiometer in diagnostic hearing evaluations. A SISI adapter provides short periodic sound pulses in specific small decibel increments that are intended to be superimposed on the audiometer's output tone frequency.(b)Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 874.9 .55 FR 48440, Nov. 20, 1990, as amended at 65 FR 2315 , Jan. 14, 2000