Recent studies on music information processing

Music information processing has been widely deployed in music industries over the years. Of course, technologies oriented to musicians have long been studied including sound synthesis on music synthesizers, desktop music production based on MIDI sequencers, and various kinds of support for composing, performing, and recording music. Such tools have already become an essential part of the music-production process. But more recently, focus has shifted from these conventional tools to new technologies that target the direct enjoyment of music by end users who are not musicians. For example, it has become relatively easy to ‘‘rip’’ audio signals from compact discs (CD) and compress them and to deal with many musical pieces on a personal computer. It has also become possible to load a huge number of songs onto a portable music player (e.g., Apple iPod) enabling anyone to carry their personal collection of music anywhere and to listen to it at anytime. A variety of factors can be given for this trend including advances in computer hardware (high processing speeds and large-capacity/small-size memory and hard disks), spread of the Internet, and provision of low-cost audio input/output devices as standard equipment. The standardization of MPEG Audio Layer 3 (MP3) in 1992 and its spread in the latter half of the 1990s and the establishment of MP3-based businesses in response to enduser demand have also played a role here. This trend is accelerating all the more in the first half of the 2000s with the proposal of Ogg Vorbis, MPEG-4 AAC, Windows Media Audio (WMA), and other compression systems following on the heels of MP3. Enterprises for delivering music via the Internet are also appearing in rapid succession. End users who are not musicians are not generally proficient in music — their knowledge of notes, harmony, and other elements of music is usually limited. Furthermore, they generally have little desire to create music. They are quite interested, however, in retrieving and listening to their favorite music or a portion of a musical piece in a convenient and flexible way. Recent research themes of music information processing reflect such enduser demand. The target of processing is expanding from the internal content of individual musical pieces (notes, chords, etc.) to entire musical pieces and even sets of musical pieces. Accordingly, research is becoming active in music systems that can be used by people with no musical knowledge. Typical technologies driving this trend are technology for computing similarity between musical pieces and for retrieving and classifying music; technology for referring to what music friends and other people listen to and for selecting music accordingly; and technology for creating advanced music-handling interfaces. Focusing on this emerging research trend, this paper introduces recent studies on music information processing from a unique perspective.