60 11 2004 pp. 675–681 675 — — * ∗∗ NTT ∗∗∗ 43.75.−z 1. MIDI DTM CD Apple iPod 1992 MP3 MPEG Audio Layer-3 1990 2000 MP3 Ogg Vorbis, MPEG-4 AAC, WMA Win- dows Media Audio ∗ Recent studies on music information processing. ∗∗ Masataka Goto (National Institute of Advanced In- dustrial Science and Technology (AIST), Tsukuba, 305–8568) ∗∗∗ Keiji Hirata (NTT Communication Science Labora- tories, Kyoto,