The pressure applied by a noseband to supporting tissue clearly depends upon the tightness/tension in the band. However, it also depends upon the curvature of the tissue underneath. Protruding areas with sharp curvature such as the left and right nasal bone locations will experience pressure concentrations whereas flat or concave areas will experience little or no pressure. Of course if the animal attempts to open its mouth, the noseband tension will increase as will the pressure at the pressure hot spots.

An expanded view of the simulated normal force/pressure profiles around the nasal bone is shown below.

Further Reading:

Casey, V., McGreevy, P. D., O’Muiris, E., Doherty, O., A preliminary report on estimating the pressures exerted by a crank noseband in the horse. J Vet Behaviour: Clinnical Applications and Research, Volume 8, Issue 6, November–December 2013, Pages 479-484