Big Ear

This device demonstrates how sound waves are focused on parabolic surfaces. A large parabola-shaped surface collects incoming sound waves and directs them to a central focal point. When two such devices are placed 20 to 60 meters apart, a whisper spoken into one can be clearly heard at the focal point of the other.

This effect occurs because waves from every point on the paraboloid reach the focal point simultaneously. The shape of the surface redirects the direction of sound propagation, turning it into a natural “sound collector”. Even very faint sounds can be heard from long distances. This phenomenon is based on principles shared by both acoustics and wave optics.

The sound-collecting properties of parabolic surfaces have been known since ancient times. The amphitheater design of ancient theaters allowed audiences to hear every sound clearly. In the 19th century, parabolic mirrors were used for military communication and sound signaling. Today, this principle is applied in satellite dishes, radio telescopes, and acoustic experiments.

“Big Ear” exhibits in open-air science museums allow visitors to experience the phenomenon of sound focusing firsthand, offering both an educational and entertaining experience.