  High-$p_T$ hadron-hadron correlations have been measured with the PHENIX
experiment in $\Cu$ and $\pp$ collisions at $\sqrt{s_{NN}}=200$ GeV. A
comparison of the jet widths and yields between the two colliding systems
allows us to study the medium effect on jets. We also present a first
measurement of direct photon-hadron correlations in $\Au$ and $\pp$ collisions.
We find that the near-side yields are consistent with zero in both systems. By
comparing the jet yields on the away side, we observe a suggestion of the
expected suppression of hadrons associated with photons in $\Au$ collisions.
