Based　on　the　bit-stream　of　ITU-T　G.722.2　speech　coding　standard,　through　the　modification　of　codebook　gains　in　the　codec,　a　compressed　domain　speech　enhancement　method　that　is　compatible　with　the　discontinuous　transmission　(DTX)　mode　and　frame　erasure　condition　is　proposed　in　this　paper.　In　non-DTX　mode,　the　Voice　Activity　Detection　(VAD)　is　carried　out　in　the　compressed　domain,　and　the　background　noise　is　classified　into　full-band　distributed　noise　and　low-frequency　distributed　noise.　Then,　the　noise　intensity　is　estimated　based　on　the　algebraic　codebook　power,　and　the　a　priori　SNR　is　estimated　according　to　the　noise　type.　Next,　the　codebook　gains　are　jointly　modified　under　the　rule　of　energy　compensation.　Especially,　the　adaptive　comb　filter　is　adopted　to　remove　the　residual　noise　in　the　excitation　signal　in　low-frequency　distributed　noise.　Finally,　the　modified　codebook　gains　are　re-quantized　in　speech　or　excitation　domain.　For　non-speech　frames　in　DTX　mode,　the　logarithmic　frame　energy　is　attenuated　to　remove　the　noise,　while　the　spectral　envelope　is　kept　unchanged.　When　frame　erasure　occurs,　the　recovered　algebraic　codebook　gain　is　exponentially　attenuated,　and　based　on　the　reconstructed　algebraic　codebook　vector,　all　the　codec　parameters　are　re-quantized　to　form　the　error　concealed　bit-stream.　The　result　of　performance　evaluation　under　ITU-T　G.160　shows　that,　with　much　lower　computational　complexity,　better　noise　reduction,　SNR　improvement,　and　objective　speech　quality　performances　are　achieved　by　the　proposed　method　comparing　with　the　state-of-art　compressed　domain　methods.　The　subjective　speech　quality　test　shows　that,　the　speech　quality　of　the　proposed　method　is　better　than　the　method　that　only　modifies　the　algebraic　codebook　gain,　and　similar　to　the　one　with　the　assistance　of　linear　domain　speech　enhancement　method.　(C)　2013　Elsevier　B.V.　All　rights　reserved.