The simplest method probably would be to split up the integrand into partial fractions.
[tex]\dfrac1{y^2-16}=\dfrac18\left(\dfrac1{y-4}-\dfrac1{y+4}\right)[/tex]
Then
[tex]\displaystyle\int\frac{\mathrm dy}{y^2-16}=\frac18\left(\int\frac{\mathrm dy}{y-4}+\int\frac{\mathrm dy}{y+4}\right)=\frac18\left(\ln|y-4|-\ln|y+4|\right)+C[/tex]
[tex]=\dfrac18\ln\left|\dfrac{y-4}{y+4}\right|+C[/tex]
[tex]=\ln\sqrt[8]{\left|\dfrac{y-4}{y+4}\right|}+C[/tex]