The　bandwidth　limitation　of　wideband　(WB)　audio　systems　degrades　the　subjective　quality　and　naturalness　of　audio　signals.　In　this　paper,　a　new　method　for　blind　bandwidth　extension　of　WB　audio　signals　is　proposed　based　on　non-linear　prediction　and　hiddenMarkovmodel　(HMM).　The　high-frequency　(HF)　components　in　the　band　of　7-14　kHz　are　artificially　restored　only　from　the　low-frequency　information　of　the　WB　audio.　State-space　reconstruction　is　used　to　convert　the　fine　spectrum　of　WB　audio　to　a　multi-dimensional　space,　and　a　non-linear　prediction　based　on　nearest-neighbor　mapping　is　employed　in　the　state　space　to　restore　the　fine　spectrum　of　the　HF　components.　The　spectral　envelope　of　the　resulting　HF　components　is　estimated　based　on　an　HMM　according　to　the　features　extracted　from　theWB　audio.　In　addition,　the　proposed　method　and　the　reference　methods　are　applied　to　the　ITU-T　G.722.1WB　audio　codec　for　comparison　with　the　ITU-T　G.722.1C　superWB　audio　codec.　Objective　quality　evaluation　results　indicate　that　the　proposed　method　is　preferred　over　the　reference　bandwidth　extension　methods.　Subjective　listening　results　show　that　the　proposed　method　has　a　comparable　audio　quality　with　G.722.1C　and　improves　the　extension　performance　compared　with　the　reference　methods.　©　The　Authors,　2014.