How can you produce infrasound?

Question

How can you produce infrasound?

Answer 1

A very large and expensive speaker can get down to perhaps 15 Hz.

The largest organ pipes get to 16 Hz.

http://en.wikipedia.org/wiki/Infrasound

Infrasound is sound with a frequency too low to be heard by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath the lowest limits of human hearing (20 hertz) down to 0.001 hertz. This frequency range is utilized by seismographs for monitoring earthquakes. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.