how to obtain the frequency response for the following given transfer function?

the transfer functin is given below H(z)=(1+z^-1){[(a0*z^-6 + a1*((z^-4)-(z^-8))+a2*((z^-2)-(z^-10))+a3*(1-(z^-12))]+ (z^-1)*[(a0*z^-6 - a1*((z^-4)-(z^-8))-a2*((z^-2)-(z^-10))-a3*(1-(z^-12))]}

how to obtian frequency response. here a0=h1+h3+h5+h7 a1=h3+h5+h7 a2=h5+h7 a3=h7 h1, h3,h5, h7 are filter tap co-efficients