The real answer is...."you don't know". And that's okay. You don't have any evidence that supports it being something supernatural. You just don't have an explanation for it. It's an unknown, that's all. Trying to attribute it to the supernatural is trying to fill in the gap of knowledge you currently have about the subject. Nothing more, nothing less.

Humans inherently want to understand things and we're very inclined, by our brains, to seek patterns and connect dots. If we can't really connect them in a way we can prove directly, we'll come up with something that somewhat fits, even if it's not supported by the evidence.

When humans didn't understand the orbits and rotations of the solar system, but saw patterns like the sun moving across the sky with different paths that correlated to the seasons, we came up with gods like Shams (Arabic, before Muhammad), Helios (Greek), Apollo (Roman), Tonatiuh (Aztec), Inti (Incan), Taiyang Shen (Chinese), Surya (Hindu) and Ra (Egyptian) and many others via various older religions. When Copernicus enlightened us as to what was actually happening, we moved away from believing in those gods because we now had an answer that satisfied the patterns we saw and was actually provable.

Your situation is similar. You experienced something: a loud noise that you could not explain while you were discussing something. You're connecting those dots, though there's no evidence to support a connection, because you want an explanation for what happened. If/when you find out what caused the noise, you'll no longer make that connection because you have the answer.