Per 
Special Containment Procedures: SCP-XXXX is to be kept in the centre of a room at least 20 x 20 x 10 metres large. This room's walls must be soundproofed to the extent that no sound produced by SCP-XXXX may be heard outside the room.
Description: SCP-XXXX is a Steinway model grand piano, with a non-cushioned non-adjustable piano stool, designated SCP-XXXX-1. While SCP-XXXX is not being observed, it plays piano arrangements of orchestral music from the classical and romantic periods. This music, designated SCP-XXXX-2, is audible to a range of 10 metres, regardless of what is between the listener and SCP-XXXX. Any person who hears SCP-XXXX-2 will make an attempt to play SCP-XXXX, regardless of how experienced this person is at playing piano music. If the person is unable to find a way to access SCP-XXXX within 10 minutes of their initial hearing will stop attempting to do so and will ignore SCP-XXXX-1 for 1 hour.
Sounds produced by pressing keys on SCP-XXXX have been electronically measured to be out-of-tune by up to 50 cents (half a semitone) sharp or flat. This detuning changes between every key played, and differs between multiple presses of the same key.
SCP-XXXX's primary anomalous effect is triggered by a person pressing a key on SCP-XXXX while sitting on SCP-XXXX-1. While the subject is playing, SCP-XXXX does not change its tuning. When the subject has finished what they intended to play, they declare SCP-XXXX to be the most beautiful-sounding instrument they have played, despite the random detuning. Subjects possessing absolute pitch determine the instrument to be perfectly in tune. After playing SCP-XXXX, subjects report all other sounds to be out-of-tune, to the opposite 'tune map' to how SCP-XXXX was detuned while playing it.1
