Final answer:
The term for 3 to 25 Hz frequencies that can travel through a building's structure is infrasound. These are below the hearing threshold of humans and can be caused by natural or man-made events. ELF waves as low as 3 Hz are utilized in specific applications like submarine communication.
Step-by-step explanation:
The term for 3 to 25 Hz frequencies that are transmitted through a building's structure is called infrasound. Infrasound refers to sound waves that are below the normal threshold of human hearing, which ranges from 20 to 20,000 Hz. These low-frequency vibrations can be generated by a variety of sources, including natural events like earthquakes, and by man-made sources such as high-voltage AC power transmission lines, which typically operate at 50 or 60 Hz.
Frequencies below 20 Hz, such as those in the 3 to 25 Hz range, are not only capable of being felt as vibrations but can also travel long distances and through various mediums, including water and the solid materials of a building's structure. Extremely low frequency (ELF) waves can reach frequencies as low as 3 Hz and are utilized in applications like submarine communication due to their ability to penetrate seawater, which absorbs higher-frequency electromagnetic waves more readily.