The words “sound” and “art” taken together make a pretty good definition for music itself, but “sound art,” as a composite term, actually refers to a particular strain of creativity. Rather than the stringing together of notes on a printed score, as in traditional musical composition, sound art is more the shaping of sonic elements, usually with very high-tech tools or in some rather low-tech primitive manner. It’s something like sculpture made for the ears rather than the eyes. Lesbian composer Annea Lockwood is one of its most eloquent practitioners.

Lockwood’s signature work is probably “A Sound Map of the Hudson River.” Twenty years ago she took a journey starting at Lake Tear of the Clouds in the upper Adirondacks all the way down to Staten Island where the Hudson meets the Atlantic. Her companion along the way was a tape recorder. But where Bartok went into the mountains of Hungary, recorded the peasants singing and used the melodic material as points of departure for wholly new compositions, Lockwood used the actual recordings of the churning, gurgling, and flowing waters of the Hudson to form a 70-minute soundscape. Released in 1989 by Lovely Music, the CD of “Sound Map of the Hudson River” has its tracking points laid out on a small map. Track 12, for instance, is the sound of the river at Garrison. After six or so minutes it flows seamlessly into the sound of the marsh at Iona Island.

A native of New Zealand, Lockwood, who turns 70 this year, has long lived at Crompond, New York near Peekskill. Her companion is the electronic music composer Ruth Anderson, 80. The pair met in 1973 when Pauline Oliveros suggested Lockwood as a sabbatical replacement for Anderson, who was then on the faculty of Hunter College in Manhattan. In 1982 Lockwood joined the faculty of Vassar College, where she is now a professor emeritus.

A few years ago Lockwood returned to the idea of a sound map and went to Europe, digital tools in hand, to record another illustrious channel. “A Sound Map of the Danube” has just been released on Lovely Music and at 167-minutes in length (spread over three CDs), it may be Lockwood’s largest and most ambitious undertaking to date. Certainly the piece bares no resemblance to Johann Strauss’ “Blue Danube Waltz,” but it’s also quiet different from Lockwood’s tribute to the Hudson.

It’s a tacky comparison, but “Sound Map of the Hudson” has taken on some resemblance to the meditative environmental New Age discs, popular of late.  That’s because it’s almost purely the sound water, beautifully mixed, with only an occasional distant strain of a passing train or some migrating birds.  (If only the Hudson itself was so clean.)

In her cartography of the Danube, Lockwood focused not just on the sound of the water, which she recorded at the shores and under the surface, but she also interviewed people who inhabit its banks.  Europe’s second longest river, the Danube stretches 1,785 miles and passes through Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, and Romania, all of which Lockwood visited over the span of three years.

Part of the mix in this new sound map are the voices of 13 people – fishermen, boat makers, inn keepers, artists, merchants and the like  who speak in their native tongues about their relationship to the river. Along with a foldout color map, the beautiful CD packaging includes translations of the folks’ remarks, which are amusing and insightful. Yet the reading is superfluous, since the emphasis is on the sonic.

Lockwood’s inclusion of the voices, foreign and abstract yet so thick with knowing accents and inflections, adds much to her focus on the sound of the Danube. Also part of the mix are many other life forms, birds and insects mainly. Though there’s no indication of the time of day of the various field recordings, the whole thing has a nocturnal, dreamlike feeling that’s captivating and engaging. Dipping into the recording at any point, one is easily swept along its channels, like a raft on a current.