Special Containment Procedures: SCP-XXXX is kept in a secure lock box in the Safe-Class Storage Wing. The keys to the box are kept in possession by the current Site Director.
I like the simple nature of these ConProcs but I feel like they are missing some things. You reference the "current Site Director" without first mentioning which site it is being stored at. As well, the idea that the keys are to be kept in possession of the current site director says to me that the keys are to always be carried by the Site Director (which doesn't really seem to be a safe way to store keys). Could do something more like The keys to SCP-XXXX's lock box are accessible only to the current Site Director.
Description: SCP-XXXX is a wax phonograph cylinder, estimated to have been created in the year 1902. The music recorded on SCP-XXXX is a slow tempo piano ballad in a 3/4 time signature. Those that have been introduced to the anomaly have been so far unable to determine the name of the piece, leading to the belief that it is an original composition by an unknown composer. As the music reaches its end, coughing can be heard, likely from the performer.
Phenomenal first description. While reading this I could imagine exactly what it might sound like!
When played, the sound produced by the object converts the surrounding area into a small country home, designated SCP-XXXX-A1. This effect only occurs in enclosed spaces and is most effective in small empty room.
This sentence leaves me wondering how the Foundation had determined that it is the "sound produced by the object" that converts the space surrounding it. As well, I am left wondering what counts as "most effective" in this context. The two sentences can also easily be combined into a much more clear single sentence: When SCP-XXXX is played in an enclosed space, the surrounding area will be converted into what resembles a small country home, designated as SCP-XXXX-A1. I also believe my suggestion and your original sentence are unclear that the small country home is always the same one and not just a small country home aesthetic.
I would move the length of the recording into the first paragraph describing the song and leave this sentence as a small statement of The effect will persist for as long as the cylinder is allowed to play." or combine it with the prior sentence as blue|When SCP-XXXX is played in an enclosed space, the surrounding area will be converted into what resembles a small country home, designated as SCP-XXXX-A1, for the duration of its song.##
The most notable characteristics of the SCP-XXXX-A1 are as follows:
It is comprised of two floors, including an attic and a basement.
So it is only an attic and a basement or is it two floors plus and attic and a basement? This sentence is just a little confusing to me and makes it hard to envision the rest.
There are two bedrooms. Based on the decor, one of them belongs to a child.
There are two bedrooms on [the first floor/the second floor/the main level/in the attic/etc.] - one of which appears to belong to a child based on the decor.
The windows in the family room look out into a large wheat field in the daytime. However, the windows in other rooms of the house are blocked by a grey wall and cannot be broken or opened.
The specificity makes me wonder about the other situations. If the living room shows a wheat field in the daytime, what does it show at night? Same for the other windows. The grey wall answers my question of "what about the other windows?" but adding the detail that these windows "cannot be broken or opened" makes me wonder if that means that the living room windows CAN be broken or opened?
With the exception of doors that would lead out of the building, there are no doors. Any existing doors cannot be broken or opened.
So there are only external doors and no internal doors, right? So what does the second line mean? Does this allude to doors that were in the room before SCP-XXXX was played? There are no doors within SCP-XXXX-A1 apart from those leading out of the structure. Any doors that existed in the converted space prior to playing SCP-XXXX become unbreakable and unopenable.
SCP-XXXX is always located and active within the room adjacent to the family room, designated SCP-XXXX-A2. It is in the phonograph in the far corner closest to the window.
Confusing sentence structure and leaves me with questions of how it would get to the phonograph if it was activated in the middle of the room while being held by someone. Consider adding details like I have suggested for clarity: The space where SCP-XXXX is played will always be converted into the room adjacent to SCP-XXXX-A1's family room, designated as SCP-XXX-A2. SCP-XXXX will convert the activation location outwardly from itself, always placing itself in the location of a phonograph located in the corner beside the only window within SCP-XXXX-A2. This will occur no matter where SCP-XXXX was activated in the original space.
The two human entities in SCP-XXXX-A2 are not real and cannot be touched or otherwise interacted with.
I want so much more detail here but I assume that is intentional to hook the reader so I won't be nitpicky :)
SCP-XXXX was acquired by the Foundation on March 14th, 1968. The owner, Nathaniel Lillson of Albany, New York, claimed to have come into possession of the cylinder after his grandfather had passed. He sought to sell it after activating it once, asserting that the experience had given him a "surreal sense of vertigo" and aggressive hallucinations.
Love it! Simple discovery! Although I'm still wondering how the Foundation got their hands on it from this description. Did they buy it and then hunt the owner down to ask why they sold it? This tells me how the owner allowed themself to be found, but not how the Foundation knew to come get it.
Incident XXXX.3: On October 9th, 1971, SCP-XXXX was activated as part of annual documentation accuracy checks. However, D-1117 did not emerge from the testing cell.
Love the idea that there are accuracy checks and this little hint at things being wrong! However, I reread the sentences twice because my dumb brain couldn't figure out what the D-class staying in their cell had anything to do with this event. I had initially read it as if they wanted to activate it but couldn't get the D-class to do so. Consider: On October 9th, 1971, SCP-XXXX was activated by D-1117 in a standard testing cell as part of annual documentation accuracy checks. After the expected two minutes and thirty seconds had passed, D-1117 had still not emerged from the testing cell.
Researchers outside of the cell could still hear the music being played from inside, but the same 9-second section had began repeating itself. MTF Eta-11 ("Savage Beasts") was then assembled to retrieve SCP-XXXX from SCP-XXXX-A1.
Tone issues in the first sentence that make the repeating detail feel less important than it is. Researchers outside of the testing cell reported that they could still hear music being played from within the cell beyond the expected length of the song. Upon investigation, it became apparent that SCP-XXXX had begun repeating a 9-second section of its song and had become caught in an infinite loop of playing. The second sentence is perfect.
Post-Incident Report: As all record has been lost to an unforeseen mishap with the handling of SCP-XXXX, the following information has been compiled and edited based on testimony of personnel within the testing cell.
I think this could do with a little more context and description. Rather than just stating that the record has been lost to an unforeseen mishap, describe directly what was lost like ##blue|Due to the two minutes of audio and video distortion during the extraction of SCP-XXXX, no verifiable evidence of the events that occurred exist. The following description of the events that transpired during this time have been compiled and summarized from the testimony of personnel involved in the incident.
After D-1117 fell into MTF Eta-11 Agent Gordon, he subsequently fell onto the phonograph and destroyed both it and SCP-XXXX. The object then let out an intense "scream"1 and reactivated SCP-XXXX-A1. This is the likely cause for the disruption in the Incident XXXX.3 file.
"and reactivated SCP-XXXX-A1" is alarming because I didn't think that SCP-XXXX-A1 was ever deactivated fully for it to be reactivated. This needs to be a bit clearer. "This is the likely cause for the disruption in the Incident XXXX.3 file." I think that this is a bit speculative for the Foundation. Without this line I inferred this on my own so no need to have it here anyway.
At this moment, Commander Rees and Hennessy, took precaution to increase the sound dampening on their headsets. Agent Gordon, however, had lost his in the aforementioned fumble with D-1117. Hennessy noticed this and acted to place his own headset onto Gordon, exposing himself completely.
Fantastic description!
In the last moments, Hennessy did what he could to suppress the sonic assault, including gathering the large remains in his gear sack and holding it close to his body.
What does "did what he could to suppress the sonic assault" entail? Everything else got a detailed description of events.
After two minutes, SCP-XXXX-A1 disappeared completely and the testing cell became silent again.
"SCP-XXXX-A1 disappeared completely" is strange for what you are describing here. I think a better way to get this point across is to say that SCP-XXXX-A1 began converting back into the original testing cell or something to that effect.
However, as the object is no longer able to enter an active state, it has been reclassed as Neutralized.
Clinical tone is a bit off. Consider: Incident XXXX.3 was the last time that SCP-XXXX was able to enter an active state. As such, it has been reclassed from [safe?] to Neutralized.