By definition the intensity of a sound source, is the power emitted from the source divided by the area of the surface covered by the sound waves.
Assuming that the source is a point source, so it emits sound uniformly in all directions, and there are no reflections, this area is just the area of a sphere centered in the point source and with radius equal to the distance between the source and the point where the intensity is measured, as follows:
If I and r are givens of the problem, we can solve (1) for P, as follows:
Since the power is the same at any distance from the source, we can obtain the new value of I, replacing in (1) the value of P and the new value of r, as follows:
The spring undergoes periodic motion. From Newton's first law, a body keeps moving until an unbalanced external force acts on it. So, the spring would continue to vibrate regularly and in repeated fashion. In the absence of any dampening force, the spring continues to oscillate.