#NEWLINE# def impedance_delany_and_bazley( frequency , flow_resistivity ) : #NEWLINE# #INDENT# '\n    Normalised specific acoustic impedance according to the empirical one-parameter model by Delany and Bazley.\n    \n    :param frequency: Frequency :math:`f`.\n    :param flow_resistivity: Flow resistivity :math:`\\sigma`.\n    \n    The impedance :math:`Z` is given by\n    \n    .. math:: Z = 1 + 9.08 \\left( \\frac{1000f}{\\sigma}\\right)^{-0.75} - 11.9 j \\left( \\frac{1000f}{\\sigma}\\right)^{-0.73}\n    \n    ' #NEWLINE# return ( ( 1.0 + ( 9.08 * ( ( ( 1000.0 * frequency ) / flow_resistivity ) ** ( - 0.75 ) ) ) ) - ( ( 1j * 11.9 ) * ( ( ( 1000.0 * frequency ) / flow_resistivity ) ** ( - 0.73 ) ) ) )