The Curvature Around the Sweet Spot Is Very Small

The inflecion line, which is the sweet spot of the region where the curvature essentially goes to zero, acts as an edge or an interface between the curved sections. It prevents vibrations from travelling through the curved sections because they are stiffer and reaching the clamped endsWhere they can eventually decay and dissipate away. The very fact that you have this zone near the lineof flextion, which is relatively flat, means it's very easy to excite more tin that zone. All the energy that's excited, most of it moves into the air and allows the not to be sustained.