ENH: noise models - added A, B, C, and D weightings to SPL
Summary
Added A, B, C and D weightings to the SPL predictions and code refactoring
Resolved bugs (If applicable)
none
Details of new models (If applicable)
Gains:
Risks
(Possible regressions?) code refactoring - point and surface noise functionality needs to be confirmed
(Changes to user inputs?) none
