One of the most important new trends in music is the area I like to refer to as ‘hypnotic music.’ It has a hypnotic quality because it is highly repetitious, and employs a consistent texture, rather than building or developing in traditional ways. Usually pieces in this genre are rather long, and they can seem tedious until one learns how to tune into the many subtle variations which go on underneath the sameness of the surface. Then very new and exciting musical experiences begin to happen.

Philip Glass’s work for the past couple of years has been at the very center of this new trend, and his ‘Music with Changing Parts’ is one of the finest pieces of this type which I have heard. It is an hour-long piece, in which electric organs ripple along in little repeated patterns, while sustained notes in viola, voice, and wind instruments fade in and out. The music uses a simple white-note scale, and most of the rhythms are also relatively simple, but the patterns shift constantly in subtle, unique ways, and enough of them are going at any one time to keep the ear more than occupied.

Glass’s latest piece, ‘Music in 12 Parts,’ is a continuation of this style, the main difference being that it uses a different structural format. It is divided into sections, or ‘parts,’ which are about half an hour long, and quite different from each other in character. Parts IV, V, and VI of the new work were presented at Village Presbyterian Church on March 26, as part of the Spencer Concerts series. Two organs were used through the evening, and the four wind players worked with various combinations of flutes, saxophones, and trumpet.

One hardly notices that Part IV is actually a labyrinth of rhythmic complexity, so smooth is its flow. Usually at least three simultaneous patterns are distinguishable, each independent of the others. Without stopping, the performers made a rather abrupt transition into Part V, which is built on a simple waltz rhythm and maintains interest through melodic shifts, particularly in the saxophones and trumpet. After intermission, they played the last half of part VI, which features quick patterns in two flutes, and many metric shifts.

In some ways, ‘Music in 12 Parts,’ or at least these three sections of the work, is less successful than the earlier ‘Music with Changing Parts.’ The transitions from part to part are somewhat jolting, and seem to go against the hypnotic character of the music, although that may have been just a performance problem. And sometimes the variation procedures do not seem as intricate or subtle in the new piece, especially during Part V.

But that is just quibbling, because both pieces are really wonderful in so many ways. The loud textures are extremely rich and sensual, and the organs and other instruments are so well blended that it is sometimes difficult to tell which instrument is playing what. The music has a sensitivity to subtle differences between modes, which can only be compared to the Indian raga system. And such finesse informs the details that the music is always interesting, although it never moves outside a small confined area. Finally, it conveys a mood which is overwhelmingly joyous. Although the music does not resemble anything by Bach, it sometimes lifts me up the way a Brandenburg Concerto does.