A Weighting

Function Aweighting(Freq As Double) As Double
    If NumberArg < 0 Then    ' Evaluate argument.
        Exit Function    ' Exit to calling procedure.
    Else

        If Freq > 0 Then
            f2 = Freq ^ 2
            f4 = Freq ^ 4
            ' Return A-weighting for this frequency.

            Aweighting = 10 * Log(1.562339 * f4 / ((f2 + 107.65265 ^ 2) * (f2 + 737.86223 ^ 2))) / Log(10) + 10 * Log(2.242881E+16 * f4 / ((f2 + 20.598997 ^ 2) ^ 2 * (f2 + 12194.22 ^ 2) ^ 2)) / Log(10)
        Else

            Aweighting = -1E+32

        End If
    End If
End Function