Question

For centuries, the ancient theater at Epidaurus has mystified acoustic engineers and tourists alike. A speaker standing at the center of the open-air stage can drop a pin or whisper softly, and the sound is heard clearly in the back rows, some sixty meters away. Popular lore long attributed this phenomenon to secret design methods or mystical geometric properties known only to the ancient Greeks. However, modern researchers have debunked these romantic theories by applying rigorous acoustic testing to the structure. Their findings indicate that the theater’s remarkable sound transmission is primarily a function of its physical materials. The rows of limestone seats form a natural acoustic filter that reflects high-frequency sounds—such as the voices of actors—back toward the audience, while absorbing low-frequency sounds, such as the wind and the rustling of the crowd. The layout of the theater, rather than any esoteric knowledge, explains the acoustic clarity. Thus, the physical properties of ordinary building materials, when arranged in a specific tiered structure, can achieve what was once considered a feat of architectural magic.

Which of the following best expresses the main point of the passage?