[Daryl]

I wondered a few years ago if there is some harmonic signature to a well struck shot ...

Obviously materials and clubhead speed are important...but the extra special something seems to be universal whether it is range ball ot ProV...

Is that certain sonic characeristic measurable?

According to TGM Book, a (Dual) Horizontal Hinge provides the perfect strike because of the same line of compression from impact to ball separation. Because the golf ball can only deform (Flow) in two directions when perfectly struck, the ball remains thicker on the line of compression. I can only guess that this is what causes the deeper resonating pitch "crack" when all of the space is squeezed from such a large section of the ball. Or is it caused by the return flow?

But does that mean that Hitters don't typically make that sound, because Layback Flows that minuscule amount away from the Line of Compression?

2-A RESILIENCE The response of the ball to different applications of force is the factor that determines how force must be applied to produce a desired result.

Resilience is the key factor in ball response. Neither a rock on a spoonful of clay will act the same as a golf ball. The ball is subjected to a violent deforming compression. The ball is actually distorted, not compressed – except for reduction of one dimension. Rubber is incompressible. Trapped air bubbles can be compressed – but not the rubber itself – it flows. It flows in two directions – but acts like a solid in the third. This third direction is the direction of the compressing force. The momentum of the violent return of flow after impact also distorts the ball by exceeding the normal dimension of the compressed point. The “kick” given to the ball by this action is an important factor in ball response. Roll of the ball on the face of an inclined striker does not account for all the action produced by such an impact, especially in imparting spin to the ball. When the direction of the compressing force does not pass exactly through the center of the ball, a spin will be imparted to the ball. It will rotate on the plane of a line drawn form the line of compression to a parallel center line.