Reported July 2005

The Sonic Golf tool uses motion-detecting sensors to help golfers adjust his or her motion to generate the sound of a perfect swing.

BACKGROUND: Robert Grober, a physics professor at Yale, has developed a real-time biofeedback device for teaching and training in golf.

HOW IT WORKS: The Sonic Golf tool uses motion-detecting sensors. When a player swings the club, sensors located in the shaft send wireless signals to a small base station receiver placed a few feet away. The receiver contains a microprocessor and a sound card that unravels the signal from the sensors and converts it into an audio "soundscape" representing the various speeds of the club during the backswing and downswing. A slow swing produces soft, low-pitched notes; a fast swing produces loud, high-pitched tones. These are transmitted back to the player through a set of wireless headphones. The golfer can then adjust his or her motion to generate the sound of a perfect swing.

WHAT MAKES A PERFECT SWING: Grober collected data during initial tests with PGA players and coaches. He found that when professional golfers swing, they generate the loudest, highest-pitched sound right when they contact the ball. They also produce absolute silence at the top of the backswing before making the transition to their downswing.

This fits with what is known about the physics of a golf swing. It is an excellent example of angular motion. The swing produces a twisting force, called a torque, on the club, changing the club's velocity. To get the longest drive, the key is how fast the club head is traveling at the bottom of the swing. The faster it is moving when it hits the ball, the more kinetic energy will be transferred to the ball, and the further it will travel.

Most professional golfers can reach a club head speed of 100 MPH at the bottom of their swing; Tiger Woods, known for having one of the longest drives in the sport, can reach speeds as high as 125 MPH. Among other key elements, Woods reaches as far back as possible at the start of the swing to extend his range of motion and give the club a greater distance over which to accelerate. He builds up the club's speed as he swings by turning his torso quickly, then drives through the ball, allowing the club head's momentum to extend his follow-through swing far around his back. The result is a long and smooth rotation of the club head.

WHAT IS BIOFEEDBACK: Biofeedback is a technique that allows people to control not just a golf swing, but also their unconscious body functions, such as breathing. The person is connected to a device via electrodes that pick up electrical signals from the body. He or she then receives audio or visual cues to indicate changes in unconscious body activities involving the muscles, skin, heart and sweat glands, among other organs. The process is often a matter of trial and error as the person learns to make adjusts to control their physiological functions.

If you would like more information, please contact:

Janet Rettig Emanuel, Ph.D.
Associate Director/Science & Medicine
Yale University Office of Public Affairs
(203) 432-2157

janet.emanuel@yale.edu

Did you know...

has some basic information about the sonic club and the technology behind it.