You give no context, but I think you may be referring to the relation between power and intensity of waves, for example, sound waves or radio transmissions.
Before getting any further into this, I want to put the kibosh on your use of W as a variable. That is the abbreviation for the watt, which is the SI derived unit for power. No way am I going the use a unit as a variable. Let me call the power P.
Through a constant medium a wave propagates in a spherical pattern. Take a sound wave for an example. Supposing that it loses no power, the wave has the same power regardless of its distance from the source. However, that power is distributed uniformly over the sphere. The intensity of the sound is power per area.
I = P/A
If r is the distance from the source, then A is the surface area of a sphere with radius r.
I = P/(4πr²)
You can see here that even if the power of the sound wave does not diminish with distance, its intensity does. The intensity would then be multiplied by the area of the receptor (the ear) to get the power of the signal that is actually received. You could increase that area by using an ear trumpet or simply by cupping your hand next to the ear.