Sunday, April 05, 2009

How A Golf Swing Could Hurt Your Hearing

I bet they didn't talk about this in the physics of golf swing.

It turns out that a new type of golf clubs can produce such a loud sound when it strikes the ball, a person may have lost some hearing because of it. This was reported in British Medical Journal v.337, p.1437 (2008).

The coefficient of restitution (Cor) of a golf club is a measure of the efficiency of energy transfer between the golf club head and the golf ball. The upper Cor limit for a golf club in competition is 0.83, which means that a golf club head striking a golf ball at 100km per hour will cause the ball to travel at 83km/h. The thinner faced titanium clubs, such as the King Cobra LD, have a greater Cor and deform more easily on impact – the “trampoline effect” – not only driving the golf ball further, but producing a louder noise than the stainless steel golf drivers. The King Cobra LD had a Cor greater than 0.83, but I understand that the current King Cobra drivers are allowable in competition and have been tuned to reduce noise.

The BMJ paper describes a man aged 55 who presented to an eye, ear, nose and throat clinic with tinnitus and reduced hearing in his right ear. He had been playing golf three times a week for 18 months using a King Cobra LD titanium club and he described the noise of the club hitting the ball as “like a gun going off”. He found the noise so unpleasant he was forced to discard the club. After detailed examination it was concluded that his hearing impairment was due to the noise of the golf club hitting the golf ball.

They may have to require ear plugs at golf courses now! :)


1 comment:

Tom said...

How are they defining Cor? Because that description is just wrong. In the elastic collision case (Cor=1), if the ball were 1/4 the mass of the club head, you expect the ball to leave at 1.6 times the club head speed. They imply the speeds would be the same.