It would be too much to say there is a heavt traffic in musical guidebooks, but not too much to salute the fact that many book publishers keep the layman in mind with a steady stream of where-to-go and what-to-know books about music. Three that have come across my desk recently typify the three categories into which musical guidebooks fit:
* Those for the complete neophyte who would like some what/where listening direction.
* References for the musician or music student who would like a lot of convenient, relevant data.
* And, in between, books for the aficionado who wants to read more deeply into the areas of music that interest him.Facts on File, a most eclectic publisher, has brought out Guide to Musical America, by Lynne Gusikoff, a somewhat useful musical atlas of the continental United States. It is broken down into regions, with attention in each to concert music, folk music, rock, pop, and country-western: selective listings of festivals and more regular settings for hearing one's favorite music in numerous towns and cities. Maps are featured, and, as a musical Michelin, the book seems to skim most of the correct high spots reasonably well. Ms. Gusikoff's skill at history-writing, however, leaves a lot to be desired: The background essays prefatory to each region are sprinkled with misinformation and seem hurriedly thrown together.It is a fetching idea, this guidebook. But, charming as she is, Ms. Gusikoff strikes me as rather naive about dipping her arms selectively into the huge vat that is America's musical richness, such that I should be uneasy sending a friend out on the road armed with nothing but her advice and directions. (Phone numbers for the halls and theaters, for example, would have been a worthwhile addition.) The book is a step, at least, in the right direction, and perhaps worth picking up.Facts on File has done better with Richard Burbank's Twentieth Century Music, a lap-size 485-pager that amounts to an almanac of premieres, debuts, and significant performances in opera, dance, and concert music since 1900, as well as ''births, deaths, and related events.'' It covers virtually every name of any prominence in Western classical music - from figures like Mary Garden to Bruno Walter to Morton Subotnick. The book finishes at 1979, reasonably recent for the mind-boggling number of pithy entries that make up the text. It is clear and refreshingly devoid of any prejudice. Newspapers and journals are where the painstaking research was done, and the reviews of others are included throughout , which adds a nice thread tracing the evolution of critical taste.Nicolas Slonimsky, the patriarch of 20-century music chroniclers (who many years ago contributed some fine criticism to this newspaper), has written a mammoth introductory essay, a tour d'horizon of compositional style during the century that seethes and throbs with opinion, is great good fun, and contrasts aptly in its red-bloodedness with the sedate tone of the information that follows.Opera buffs have acquired another treasure in George Martin's most recent book, The Companion to Twentieth Century Opera, put out by Dodd, Mead & Co. The ''Companion'' contains detailed synopses, timings, even some musical quotations, for almost 100 operas written since before World War I. Strauss and Puccini are the earliest composers, of course, Sir Michael Tippett and Hans Werner Henze being among the most recent, with operas by Janacek, Prokofiev, Britten, Bartok, and Carlisle Ford, among others, along the way.Mr. Martin is no mere opera statistics authority. He is an accomplished historian and writer. His seven introductory essays, on various opera-touching topics, reveal again (as in his previous books) his fine mind for the culturally historic placement of events or people. They are among the finest efforts I have read recently.There are some statistics in the book, but here, too, Mr. Martin uses them for an overview, examining just what operas have been done in some 20 opera houses around the world. What the numbers tell about tastes and the ever-languishing commitment to modern opera is valuable, if sobering.Although one might take issue with Mr. Martin's selectivity (works by noted opera composers like Paul Hindemith, Samuel Barber, Marc Blitzstein, Hugo Weisgal, Andor Kovach, and Elie Siegmeister, for example, are not even mentioned), what we have in this hefty book is an unpolemical, dignified reminder of the volume and worth of works of opera conceived in our time. Bravo!