Some noise from floors is acceptable however how much is subjective.
Pull back the carpets you should see the line of the joists from fixings, put your weight on and off the joists, you should identify the problem areas. The type of noise will help identify, high pitched = metal, wood on wood, clunking etc.
You may need to cut a hole in floor to inspect, joists sizes, hangers, straps, studwork, pockets or boards flying over joists, you can also feel any dabs from room below.
There is no single solution your contractor should try and work in a logical progression looking at the simplest and least invasive methods.
Your tiles should have a ply subfloor or an islolator membrane.