Audio engineers and acousticians have been putting lots of effort on realizing three-dimensional (3D) audio technologies aiming at realization of truly high-fidelity audio, highly realistic virtual reality environment, and next-generation telecommunications. Fortunately, such efforts resulted in establishment of some theories providing physical and mathematical backgrounds for 3D audio technologies and some have been realized in laboratories. However, to apply them to consumer use, there remain lots of practical issues to be solved. This paper reviews state-of-the-art 3D audio techniques and prospects for applying them to a consumer use.