While computers create sound, it is trialled in the real world. Here, Ping mics up a mannequin to capture impact feedback.

Strident trident

The duration of impact sound is one of three areas golf club engineers target when manipulating impact sound. The others are amplitude or loudness, and frequency or pitch.

“For frequency, imagine a string being plucked,” explains Mizuno’s US head of R&D David Llewellyn. “It will vibrate in several different modes. The first would be the entire string bouncing up and down. Then there are ripples along the string, and then ripples along the ripples. The golf clubhead vibrates in the same way. There are actually an infinite number of vibration modes, but only the first few contribute much to the sound. By focusing on those important modes we can adjust the head geometry to get the head frequencies we want.”

For the driver, typical frequencies are 2,500-5,000Hz – though it’s not quite as simple as that. As Beach says, different parts of the clubhead vibrate at different frequencies, so the ultimate sound the club makes is actually more of a chord than a note. According to Llewellyn, a difference of 1,000Hz in that tone can mean a club that sounds sweet, and one that sounds cracked.

Typical driver amplitudes range from 98-118 decibels – that’s compared to a hand drill at 98dB and a rock concert at 115dB. “You will generally find that drivers designed for lower ball speeds are engineered to produce louder sounds,” adds Ping’s Jertson. “Stronger players, the guys on Tour, hit the ball harder, so generate a louder sound anyway.

“We would mostly engineer this through geometry. Sharper corners reverberate at harsher frequencies, while smooth, rounded shapes give more muted sounds. Our G25 model, a driver that can be used by all standards, has a larger footprint and its crown is flatter, which boosts forgiveness while naturally giving a bit more of a powerful sound. The i20, geared towards the higher swing-speed golfer, has a more rounded shape and gives a slightly more muted sound.”