Leonel had learned a lot from his time in the Void Library. Among the Fourth Dimensional information he had learned about, he had read a lot about the culture of the Dwarven Race.
He had learned about their love of darkness and the underground, he had learned about their mating rituals and practices, their love of nature, and he had also learned about their love of music. It was said that the Dwarven Race built their homes into mountains not just for darkness and safety, but also because it gave them the greatest control over the architecture.
The Dwarven Race didn't build their homes… they sculpted them.
By taking this approach, they were able to form a sort of resonance with the earth. The sounds traveled perfectly, better than even the greatest concert halls of Earth.