Method and apparatus for decoding an audio signal

An apparatus for decoding an audio signal, the apparatus comprising:

• a decoding device configured for:
• receiving a downmix signal and spatial information;
• generating a pseudo-surround signal including a left output signal and a right output signal by applying surround converting information to the downmix signal;
• and
• an information converting part configured for generating the surround converting information using the spatial information and a Head-Related Transfer Function (HRTF), wherein the surround converting information includes first converting information for generating a left output signal by being applied to a left channel of the downmix signal, second converting information for generating a right output signal by being applied to a right channel of the down mix signal, third converting information for generating the right output signal by being applied to the left, channel of the downmix signal, and fourth converting information for generating the left output signal by being applied to the right channel of the downmix signal,
• wherein:
• the downmix signal is generated by downmixing a plurality of channel signals,
• the spatial information is determined when the downmix signal is generated,
• the downmix signal corresponds to a mono signal or a stereo signal,
• the spatial information includes at least one of a channel level difference and an inter channel coherence, and
• the pseudo-surround signal has virtual multi-channel sound.