How many times has one mentioned a Philip Glass or Steve Reich recording to a friend whose response involved a condescending look and a wry comment like: 'Oh no, not another one of those New Age records!'?

After a decade when both music critics and public alike turned up their collective noses at the idea of new instrumental music, categorising any composer or musician who came within a hair's breadth of a minimalist sound or tinted oblique album sleeve as one of those 'new agers', comes an analysis which finally puts it into the perspective it deserves.

A product of 14 years of broadcasting on WNYC, New York, John Schaefer's book is a study of that music which "falls into the grey area between classical and rock, ethnic and jazz. Eastern and Western, electronic and acoustic." Its eleven chapters are "organised according to how music sounds" thus sketching out in some detail just what is Minimalism or World Music. In an area where definitions get convoluted and confused, Schaefer argues his points with exceptional clarity - each category backed up with a personally selective but mind-boggling array of dense discographical information.

The first three chapters take in electronic music, process music, and electro-acoustic music. Here Schaefer traces developments from such early 20th Century inventions as the Russian Theremin Vox (a pulsing antennaed device operated by the passing of hands near it, and later used by - of all people - Led Zeppelin and The Beach Boys!) through to Stockhausen's intense electronic researches of the 1950s, right up to the present work of instrumentalists Kitaro, Eno, and Vangelis. When it comes to electroacoustic music, Schaefer finds himself in the murky waters of trying to define what is and what is not 'New Age music'. Californian 'anti-frantic' guru Steven Halpern is cited as the best example of what the genre aspires to - a healing music whose effect on the listener is as important as its content. Though Schaefer is for the most part sceptical, he concludes with the interesting comment, "though much New Age is indeed devoid of any musical content, some of it is good despite itself!"

Without a doubt the book's best chapter is that on Minimalism, where the work of La Monte Young, Terry Riley, Philip Glass, and Steve Reich is discussed in depth. Minimalism is that music which uses specific additive or cyclical structures and involves repetition and the creation of musical patterns. Its most famous exponent is the multi-million selling Philip Glass, but to his credit Schaefer gives equal coverage to the other innovators of the form. At least we get a proper discussion of the importance of its inventors, La Monte Young and Terry Riley. Young, due to his disinterest in the recorded medium, has sadly been overlooked by most writers when chronicling the development of the latterday avant garde, but his contribution was and still is pivotal.

After studying at Berkeley in the 1950s, La Monte Young ventured to Darmstadt to work with Stockhausen. Soon he was to return to America, this time New York, and team up with the Fluxus art movement of Yoko Ono and the more extreme musical firmament of The Dream Syndicate (uncredited here) with John Cale and Marian Zazeela. It was then that Young came up with the 'just-intonation' system of piano tuning, where flats and sharps are differentiated and all the overtones could be heard ringing clearly. Now Western music could be as interesting and exotic as its Eastern counterpart. Both Young and Terry Riley developed a mystical style of music and would later travel to India together; but back then, in the early 1960s, their work was attracting interest not only from musicians but from people like Allen Ginsberg and Michael McClure.

Riley's In C, in 1964, became the most important Minimalist composition of its decade, while Young's Well-Tuned Piano performance piece was so flexible that even now it's still being added to. Schaefer elucidates on Young's remarkable 'Dream House' experiment - "a continuous frequency environment in sound and light" that would last from days to an astonishing six years.

Considering this and the fact that Steve Reich was working extensively on tape loop composition in the mid-1960s, it's not surprising that Brian Eno comes out of this book as more of a clever applicator of other peoples' ideas than an original talent in his own right. Reich certainly gets his dues here, as does Philip Glass, and we learn that both men studied together at the prestigious Juillard School in 1958. Reich's growth from tape manipulator to orchestral composer of merit is detailed, while we learn little known facts about Glass's career - such as the 20,000 dollar debt that he and stage designer Robert Wilson had to incur after two sold-out performances of Einstein On The Beach at the New York Met in 1976!

World and ethnic musics are included in the book because the author simply and effectively argues that they introduce "new sounds to Western ears." The work of The Beatles, Ravi Shankar, John McLaughlin, and risque jazzers Ralph Towner and Don Cherry is earnestly dealt with in the World Music section, though that of Peter Gabriel and Jon Hassell (American avantist and inventor of the term 'world music'!) is sadly neglected. Still, the author's citing of Shankar's East Greets East album of sitar/tabla and Japanese koto/shakuhachi music as a good example of world music interaction shows a keen analytical mind ably sorting through what is in this book's case a dizzying array of discographical choices.

Still, for all the strengths this book has, there are weaknesses. Schaefer's discussion of ethnic music is inordinately technical when it comes to Indian and Indonesian musics but surprisingly superficial with regard to African music. Given the success of, say, Youssou N'Dour from Senegal and Malian kora music in the West over the last number of years, one would think it merited inclusion in Schaefer's 'West African' section. Where the author is strong is on the American side, with detailed accounts of the sound experiments of such composers as David Rosenbloom, Daniel Lentz, and David Behrman; interesting analyses of new American instruments, such as the bowed piano (miniature piano in the form of a cello) or the steel cello (a piece of industrial scrap metal bent into a 'C' shape and wired for sound); or in just plainly looking at the contributions of Charles Ives or John Cage.

Where he is weak is on the European side. Only cursory glances are given to Debussy, Satie, Stravinsky, Messiaen, Varese, Schoenberg, and Webern. Such groups as Can (comprising of Stockhausen pupils and the originators of noise music and spontaneous music) and Cabaret Voltaire (English assimilators of musique concrete and innovators of house music a decade before its popularity) are ignored in favour of hackneyed accounts of the importance of Tangerine Dream and Mike Oldfield within the rock area of new music. Norway's finest musician, jazz saxophonist Jan Garbarek, somehow becomes a Swede(!) - and what of Michael Nyman and John Cale (who, after nearly four decades of activity, surely deserves some credit)?

Even if Schaefer's method can trip him up, like at the end of the 'New Jazz' section where he describes a record as "one of the very best albums of eclectic jazz/new music/world music, from the improvised Minimalism etc", New Sounds is lengthy and diverse enough to attract the interest of even the sternest critics. The inclusion of a chapter on unusual folk arrangements, specifically Irish and British, again demonstrates an awareness of musicology that is enviable. Few writers outside Ireland could so lucidly trace Irish folk music's renaissance from Sean O Riada's symphonic traditionalism of the 1960s, through the various Planxty and Bothy Band incarnations, all the way up to the latter-day work of composers like Micheal O Suilleabhain (now on his third album for Virgin Records). Outside Ireland, people like France's Alan Stivell and Britain's Fairport Convention get justified and long-awaited credit for the creation of an electric folk music that is as resonant today as it was in the 1960s and early 1970s.

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