Item #: SCP-723
Object class: Safe Euclid
Special Containment Procedures: SCP-723 is to be housed in a security locker at site-██. Requests for experimentation should be submitted in writing to Dr. █████ and may be approved or denied at his discretion. SCP-723 may be safely handled by authorized research personnel so long as the 3.5mm audio input jack does not come into contact with any electronic device capable of producing sound. SCP-723s volume knob is to be kept in the “Off” position except for testing purposes. Class D personnel are to be used to connect and disconnect SCP-723 from testing devices.
Description: SCP-723 appears to be an ordinary set of ███ brand computer speakers (left and right side speakers designated SCP-723-1 and SCP-723-2 respectively); the speakers appear to function with no apparent power source, as the power cable has been cut 6mm down from the insertion point. Testing indicates that SCP-723 is resistant to damage caused by sonic vibrations but is otherwise susceptible to damage from outside sources.
SCP-723 is easily taken apart and reassembled and its internal workings are identical to that of an ordinary computer speaker of its make and model. SCP-723 has an anomalous quality in that whenever the speakers are plugged into an appropriately sized audio jack and sound is played, the speakers emit the sound with perfect clarity and at the decibel level the sound would normally be heard, regardless of the setting of the volume knob on the front panel of SCP-723-2(Save for the "Off" position which does turn SCP-723 off). SCP-723 will play any known audio file in this way. Initial testing of SCP-723 deafened Researcher ██████████ when he attempted to play a recording of test log [Redacted].
Level two personnel should see addendum xxx-y
During Audio testing of SCP-723 a new property was discovered. When SCP-723s volume knob is switched to the "Off" position or otherwise unplugged from an audio device SCP-723 begins to emit an inaudible tone in the form of infra-sound. The tone was determined by testing equipment to be at 18Hz, the resonance frequency of the human eye. While this effect manifests, subjects within SCP-723s range will begin having visual hallucinations. These hallucinations intensify with sound volume and exposure time and will eventually cause paranoia and retinal trauma.