Goal of tests: To see if certain soundwaves can negate 939's ability to detect prey.
Note: The main method of 939's detection could be related to vibrations in the air caused by sound. If this is true, there may be a way to safely negate such waves and effectively render our operatives invisible to 939. -Dr Isaac Calloway
Test UMBRA-1.1
Subjects: SCP-939-34, SCP-939-35, SCP-939-36, SCP-939-37
00:00 SCP-939-34 introduced to chamber.
00:05 Sounds of varying frequencies played. Subject reacts to air vibrations with confusion.
00:10 Extremely high-frequency sound played. Subject reacts with discomfort and hostility.
00:15 Extremely low-frequency sound played. Subject reacts with confusion.
00:20 Frequency adjusted. Low frequency sound played. Subject does not react.
00:30 Low frequency sound played. Several loud noises played overtop. Subject does not react.
01:00 SCP-939-35 through 37 introduced to chamber. Subjects react as expected.
01:10 Low frequency sound played. Several loud noises played overtop. Subjects do not react.
Test results: Frequency found, subjects ready for test UMBRA-1.2.
Test UMBRA-1.2
Subjects: SCP-939-34, SCP-939-35, D-08281
00:00 SCP-939-34 introduced to chamber.
00:10 Low frequency sound played. Subject does not react.
00:20 Class-D personnel introduced to chamber. D-08281 reacts with distress, creating noise. Subject does not react.
00:35 Extremely high frequency sound played overtop of low frequency sound. Subject reacts with hostility towards source of sound, but seems to be unable to detect D-08281.
00:50 D-08281 removed from chamber.
01:20 SCP-939-35 introduced to chamber, with high frequency sound emitter attached. Subject reacts with hostility, and test is halted before any physical harm can come to either subject.
Test results: Success. Proof of concept established. Subjects ready for test UMBRA-1.3
Test UMBRA-1.3
Subjects: SCP-939-34, dummy target, MTF unit B-04416
00:00 Dummy target set up in end of chamber.
00:10 SCP-939-34 introduced to chamber.
00:15 Low frequency played. MTF B-04416 enters chamber, outfitted with delivery device Alpha-Gamma-23. Subject does not react.
00:25 MTF B-04416 fires delivery device at dummy target. Subject reacts with hostility towards dummy target, ignoring MTF B-04416
Test results: Success. Construction of portable frequency-emitting devices authorised.
SCP-939-34 through 37 outfitted with remote portable frequency-emitters, set to low frequency. Handlers designated as MTF Umbra-1, outfitted with long and short range handheld delivery weapons, with high-frequency ammunition. MTF Umbra-1 also outfitted with emergency extreme high-frequency emitter, designed to cause discomfort and pain in SCP-939 subjects, and filtration devices implemented in masks to negate compound AMN-C227. SCP-939-34 to 37 outfitted with remote detonators as failsafes.
Note: Although the devices stop 939 from hearing certain frequencies, thus removing risk, MTF agents are recommended to mantain radio silence while Umbra-1-939 units are deployed. - Dr. Calloway
MTF UMBRA-1, Designation "Good Boys"
MTF Umbra-1 are to be deployed in scenarios that involve enemy personnel in an open environment. Umbra-1-939 units can be deployed to seek and destroy enemy forces, or as assassination tools.