Foreword: After in-house maintenance and the library's engineers could not find or suggest a source of the sound, the Foundation was alerted to the phenomenon by an embedded executive, who also contacted the Unusual Incidents Unit (UIU) branch of the Federal Bureau of Investigation. A premier firm of acousticians (1 representative sent) was consulted at the behest of the executive staff.

The Foundation approved the collaboration, given clearance from the Ethics Committee that the acoustician be amnesticized by any means necessary in the event of a classified information breach. The following are excerpts from conversations between the team members.

Present company includes Agent Wells (recording via an attached condenser mic), acoustician Dr. Ciaph Fullfölja, Ph.D., and Agents Drumel and Cyllus of the UIU. Extraneous dialogue has been removed and indicated accordingly.

The team enters the building from the 1st Street SE entrance, and into the library's mezzanine. A droning sound is picked up on the condenser mic as they enter.

[BEGIN LOG]

Agent Drumel: I thought libraries were supposed to be havens for peace and quiet.

Agent Cyllus: It has to be a good 70 dB. What would you say, doctor?

Dr. Fullfölja: Let me check. (Shuffling of clothes can be heard, followed by clicks.) 63.5 dB.

Agent Drumel: Not bad, Katherine.

Agent Cyllus: It was a cinch. You're an easy 70 almost all the time and it's about that annoying in here.

Agent Drumel: Yeah well the patrons seem to agree; there's no one here.

Agent Wells: Except for our hostess…

Footsteps are heard approaching, echoing through the large room.

Carla D. Hayden: Welcome, welcome. Thank you all so much for coming today.

Agent Drumel: Huh?

Carla D. Hayden: Yes, I know, it is bad. It's actually a bit quieter in here than elsewhere in the library, I assure you, and also a bit quieter than the noise from the street outside. Sorry to meet you all under such uncomfortable conditions. But we appreciate your help and desperately need it. This is killing the library.

Agent Wells: Happy to be here.

Carla D. Hayden: I wanted to meet you all together, as I believe you can benefit from each other. Is there anything I can explain further that might help you?

Dr. Fullfölja: We had spoken earlier about schematics.

Carla D. Hayden: Yes, of course. Those will be made available to you within the hour.

Agent Drumel: I think I've heard enough.

Agent Cyllus: (Quietly) Start acting like a professional, please.

Agent Drumel: Yes ma'am. We'll begin immediately.

Carla D. Hayden: Yes, thank you. The staff has been made aware of your presence, please don't hesitate to contact me or my team for help. Thank you all again.

Per Agent Wells, at this time Dr. Fullfölja began unpacking a carryall bag and assembling an array of standing microphones around the mezzanine and the surrounding rooms. Agents Drumel, Cyllus, and Wells began walking the library.

Agent Drumel: So what do you think of all this, hearing it in person now?

Agent Cyllus: It sounds like a paper factory. But it could still be a lot of explainable things.

Agent Drumel: Oh? Like what?

Agent Cyllus: Hums like these are common in electrical systems, especially those housed in aged structural components, both of which are ubiquitous in this library.

Agent Drumel: Sure, but they shut off the electricity briefly last week and the sounds remained.

Agent Cyllus: That might not rule out the effects of capacitance. Enough charge from the constant stream of supplied electricity over the last hundred years stored on big enough capacitors could still be shedding some of the energy via sound. Or what about seismic waves and their potential reverberation with the architecture of this structure, it acting as a kind of echo chamber? There's got to be natural frequency to this library as a whole; hit it with the right wavelength of sound waves and it can cause a number of overtones.

Agent Drumel: But the subsoil of this region isn't conducive to such complete propagation of sound waves, nor is seismic activity a concern here.

Agent Cyllus: Right, the library must be on an ancient burial ground, then. Look, it's no complete theory, not yet. It's mere shooting in the dark because there isn't any other rational explanation to move forward with. (Pause) We'll need more data. Our acoustician friend should help with that. I'm not convinced that because the civil engineers couldn't find a source we should be looking for something preternatural. And I hate that you pushed that agenda so quickly out of the gate with our esteemed colleague. I don't think he was impressed.

Agent Drumel: Alright, my turn. What about the mosaic of Minerva there at the entrance?

Agent Cyllus: What about it?

Agent Drumel: Did her presence inspire any ideas as to what might be going on?

Agent Wells: Minerva is the Roman goddess of wisdom. Seems like her placement here is explained easily enough.

Agent Drumel: Yes, she is, but what's less known is that she's also the sponsor of strategic warfare. According to the myths, she was born in battle armor for crying out loud. She lived inside Jupiter, her mother having been swallowed by him, and it was said she was the source of a constant pounding and ringing to such an agonizing extent that Jupiter commissioned the iron god Vulcan to craft a hammer to split Jupiter's head open and release her from within him.

Agent Cyllus: I fail to see the connection.

Agent Drumel: What if we are Vulcan here? Or better yet, the hammer?

Agent Cyllus: Out of the millions of documents and countless mythos contained in this library, you think that the entirety of the events occurring here can be pinned down to a few sentences tangentially ascribed to Minerva?

Agent Drumel: But that's my point, Katherine. Ideas can manifest in physical ways when they become crowded. How many thoughts can you simultaneously fit inside your head, for example, before it manifests as a headache? Has it ever been asked; what happens when you physically amass such a massive collection of ideas? Do they, like the ideas in our minds begin to compete with one another for space, a kind of warfare for their actualization in the real world? I think it's no mistake that this phenomenon is happening here, in the largest library in the world. And it might not be Minerva herself, but I don't think we're going to find answers in the acoustics of the building, the reverberation capacity of the solid media, or in the electrical circuits.

Agent Cyllus: It's poetic, and it's true that only a certain amount of data can be present before an event horizon, but I don't think abstract ideas work in the same way, and I certainly don't think they are alive, waring with one another.

Agent Drumel: Maybe not ideas themselves, but they are the germinal form of all living things and actions. Once you, Katherine, were just a thought. Like me, like all of us. Any structure, government, movement whether artistic or political, all once only an idea. What if what's manifesting here is another type, or species of germinated thought?

Agent Cyllus: I'm not sure what you're getting at.

Agent Drumel: What about you, Agent Wells? What do you think?

Agent Wells: I think the noise got a lot quieter when we passed the Hispanic Reading Room.

Agent Drumel: …you sure?

Agent Wells: Let's see.

The agents turn and walk towards the Hispanic Reading Room. SCP-4058 notably diminishes in volume.

Agent Drumel: Well I'll be.

Agent Wells: I couldn't help but notice after I tuned you two out.

Agent Drumel: (Chuckling) I wish I could do that. That's a gift.

Agent Cyllus: What do you think it means?

Agent Wells: I… don't know. That it is not a constant volume throughout the library could support your theory of capacitance or reverberation… I can't think of a reason why European ideas would be fighting with each other more than Hispanic ones though.

Agent Cyllus: What are you doing, Agent Wells?

Agent Wells: Inspecting the bookshelves themselves. We've seen such things at the Foundation, you know.

The agents are radioed and asked to head towards the mezzanine to reconvene with Dr. Fullfölja.

Agent Wells: Doctor, I don't mean to be presumptive, but I believe they've recorded some samples already.

Dr. Fullfölja: Yes, they have. I'm noise mapping. I'm taking sound pictures, essentially, in order to model the propagation of the noise generated by… whatever it is making this sound.

Agent Wells: Any chance it will tell you the source?

Dr. Fullfölja: Not exactly; this is primarily for predicting the effects of noise mitigation strategies that I'll recommend later. My role here is more prescriptive than it is investigatory. After I model the acoustic performance of this building, I could theoretically postulate sound sources and see if the expected behavior matches the pictures of what we're observing here, but…

Agent Cyllus: …but what?

Dr. Fullfölja: (Chuckles) As far as the detection of a sound source goes, no technology is even remotely close or will be in the distant future to what you and I have already brought to the table; ears.

Agent Cyllus: I see. Do you need any help?

Dr. Fullfölja: Frankly, I do — this will take some time — but this is a one-person job, I'm afraid. Besides, it's necessary that I have a sterile environment, and that means we'll all have to exit the building for me to complete the mapping.

Agent Wells: Would it be okay if we're on another floor?

Dr. Fullfölja: …the basements would be acceptable, I suppose.

Agent Drumel: Before we go… we noticed some significant discrepancies in volume regarding the noise back there. Any idea why that might be causing that?

Dr. Fullfölja: Sounds like it could be negative interference; the sound waves hitting each other in a way that provides some cancellation. Could also be a function of the immediate environment… temperature, humidity, even the materials of the books within the individual rooms can contribute to changes in acoustic performance for the same sound. Where did you notice this?

Agent Wells: Near the Hispanic Reading Room.

Dr. Fullfölja: Get back to me about it. I'll see if the sound models include that bit.

The agents locate the entrance to the basement levels, however, this entrance is locked with a security gate.

Agent Drumel: Excuse me… Excuse me, hello. My name is Agent Drumel, this is Agent Cyllus and Agent Wells. We are hoping to gain access to the basement.

Librarian: I'm sorry, the basement is off limits to patrons.

Agents Drumel and Cyllus produce their FBI badges.

Agent Drumel: We'd appreciate it.

Librarian: Right this way.

Agent Wells: (Quietly, to Agent Cyllus) …must be nice.

The agents gain access to the basement.

Agent Drumel: So, what is down here?

Librarian: On B1, some very important stuff. Original manuscripts, the original library of Thomas Jefferson, presidential memoirs dating back to George Washington… do be careful, please. B2 is where we keep the oldest, most valuable items… like original vellum artifacts and other things of the utmost historical significance.

Agent Wells: Has anyone been down in the basements since this began?

Librarian: Yes, Mrs. Hayden and a few others a couple days ago. They didn't find anything unusual, I don't believe. Well… unusual for these circumstances, I guess. Oh! Speaking of which, you reminded me… down there… it's damaging. Here, take these.

The librarian hands the agents noise-dampening earphones. The agents thank her and descend the staircase to B1. As they descend, the condenser microphone is overwhelmed by a markedly louder droning noise. Only a partial transcript is possible during this time.

Agent Cyllus: Wo—(indistinct) endless bookshelves.

Agent Drumel: (Indistinct) small portion of the 800 plus miles (indistinct)

Agent Wells: Why is it so much louder here? Could the source be here?

Agent Cyllus: Let's keep walking, maybe (indistinct)

After coursing the level, the agents have no leads as to a source and are at a loss as to how to proceed. Agent Wells inspects the bookshelves again, accidentally knocking a volume off in the process, which opens as it hits the floor.

Agent Drumel: What did y—(indistinct)

Agent Wells: I noticed something odd when I read this page, look.

Agent Cyllus: …a treatise on… phlogiston? I don't see (indistinct) specifically speaking.

Agent Wells: Read some of it.

Agent Cyllus: (Indistinct)—y God.

Agent Drumel: Who's v—(indistinct) we hearing?

Agent Wells: I don't know. Is it the same for you two?

Agent Drumel: It's de—(indistinct) white British m—(indistinct)

Agent Wells: The author checks out.

Agent Cyllus: I just can't (indistinct) saying, though. (Indistinct) muddled.

Agent Drumel: Well, this (indistinct) something.

At this time, Agent Wells time collects the books and motions to the UIU agents to leave. They walk up the staircase and return the headphones to the librarian.

Librarian: Excuse me, but those books are not for checking out.

Agent Wells: Contact Mrs. Hayden. Tell her it's Agent Wells.

Librarian: (Ringing) Hello— hey it's me. Could you tell James that I need to get a message, err, a question to Mrs. Hayden? It's about the investigation. Yes, the agents, they want to take some items from the B1 with them. I don't know. No, it is Agent Wells. Wells. Yes, I'll wait. (Pause) O— Okay. (Hangs up) Well. Have a nice day, Agent Wells.

Agent Wells: Thank you, you too.

Agent Cyllus: (Quietly) …must be nice.

[END LOG]