Here's something I wrote, feel free to assign a number.
Special Containment Procedures: Item is to be kept in a well padded room. A speaker, also protected by padding, is to remain in the room at all times, producing a loud, 5 second burst of white noise at 10 second intervals. No metal objects or hard surfaces of any kind are to be brought into the room. Any personnel exposed to the sound of the item are to be isolated, equipped with a cyanide capsule, and recorded with a video camera until the moment they expire.
Description: The item is a small metal pin, 3 cm in length. Reports state that the introduction of the object to any area results in a hum, increasing in volume, eventually drowning out all the ambient sound of the area. After that, the hum itself will fade out, resulting in absolute silence. Depending on the area, the entire process takes 5-30 seconds. If the object is removed from the area, ambient sound will resume within 60 seconds. The silence may also be broken by a loud burst of sound.