The code provided can be easily modified to study these situations. However, be warned that for many of these, it may not be easy to find a unique solution, even with Mathematica. Alter the geometry, e.g. not an equilateral triangle. 1 A coordinate axis helps. Place the Twisted Turtles at 0 and Hogroast at 2000.
Sound intensity varies inversely as the square of the distance from the source.
The actual value of k has no bearing on the solution. We can verify this by setting the derivative of the total noise function to zero and solving. Only the first of these is real. The quietest point is midway between the bands. Solution to Problem 2 Use the same coordinate system.