A method of processing an audio signal, comprising: receiving a downmix signal including at least one object signal, wherein the downmix signal is a mono signal; receiving object information extracted when the downmix signal is generated; receiving mix information for controlling the object signal; receiving mode selection information including information indicating one of a normal mode, a karaoke mode, and a solo mode; receiving enhanced object information corresponding to a residual signal generated in the course of downmixing a background object and an independent object and used for extracting said background object and independent object during audio signal decoding; if the mode selection information indicates the normal mode, generating multi-channel information which is information for upmixing the downmix signal and is based on the object information and the mix information using output mode information, the output mode information indicating how many signals are used for output; and generating a multi-channel output signal by applying the multi-channel information to the downmix signal; if the mode selection information indicates the karaoke mode or the solo mode, extracting the background object and the independent object from the downmix signal using the enhanced object information and the object information; and if the background object and the independent object are extracted, rendering the background object or the independent object based on the mix information, the rendering comprising: if the mode selection information indicates the solo mode, controlling the background object based on the mix information, if the mode selection information indicates the karaoke mode, controlling the independent object based on the mix information. receiving a downmix signal including at least one object signal, wherein the downmix signal is a mono signal; receiving object information extracted when the downmix signal is generated; receiving mix information for controlling the object signal; receiving mode selection information including information indicating one of a normal mode, a karaoke mode, and a solo mode; receiving enhanced object information corresponding to a residual signal generated in the course of downmixing a background object and an independent object and used for extracting said background object and independent object during audio signal decoding; if the mode selection information indicates the normal mode, generating multi-channel information which is information for upmixing the downmix signal and is based on the object information and the mix information using output mode information, the output mode information indicating how many signals are used for output; and generating a multi-channel output signal by applying the multi-channel information to the downmix signal; if the mode selection information indicates the karaoke mode or the solo mode, extracting the background object and the independent object from the downmix signal using the enhanced object information and the object information; and if the background object and the independent object are extracted, rendering the background object or the independent object based on the mix information, the rendering comprising: if the mode selection information indicates the solo mode, controlling the background object based on the mix information, if the mode selection information indicates the karaoke mode, controlling the independent object based on the mix information. if the mode selection information indicates the solo mode, controlling the background object based on the mix information, if the mode selection information indicates the karaoke mode, controlling the independent object based on the mix information.