Really, we don't need that level of complexity to explain what's going on here. It's easier just to assume that for a light source emitting light in all directions, individual photons are like particles that are emitted in random directions. So, what you'll find at the microscopic level is that the intensity of the light isn't adjustable continuously, but rather it adjusts in "steps" equivalent to the energy of one photon. In other words, it is quantised. If light was just a wave, then we'd expect the intensity to vary in a continuous way.
Only occasionally, assuming your detector only covers one portion of the spherical surface surrounding the light source.
In the sound wave the intensity of sound is determined by the maximum distance that each air molecule is displaced from its equilibrium position as the wave goes past. With light, the intensity is determined by the maximum amount by which the value of the electric or magnetic field at a given point in space varies as the wave goes past. That's the wave picture. In the particle picture, the intensity is determined by how many photons go past that point in space every second.
