MUSIC BY women is not totally unknown; Clara Schumann has been respected (rather vaguely) for more than a century, and Amy Beach has achieved a fair measure of recognition--long overdue--during the last decade. But the fresh material brought to light by Leonarda Records documents in sound what we might have suspected: that women have been composing music for as long as men and, on the average, with equal skill.

No female Bach or Mozart has been unearthed so far; such mastery can result only from a uniquely happy meeting of heredity and environment, and until very recently women have lacked the environment. But the women presented by Leonarda easily match the standards set by journeyman male composers in their respective periods. They range chronologically from St. Hildegard of Bingen, who was born in 1098, to Sarah W. Aderholdt, born in 1955. The varied forms and styles include a plainchant "Kyrie Eleison," a baroque mass and French baroque secular cantatas, a lot of 19th-century Lieder (including quite a few small masterpieces) and a wealth of contemporary chamber music, including one real oddity: a collection of pieces for bassoon quartet.

But on the evidence presented by Leonarda, the golden age of women composers is right now--and perhaps it is the prelude to a platinum age in the next century. The quality of contemporary works on the Leonarda label may partly reflect the company's orientation toward the present (it also seems to have a penchant for vocal music), but it is hardly fanciful to see in this burst of creativity a reflection of the improved status of women in the last generation. It is risky to attach the title "masterpiece" to contemporary work, but for several of the modern works--particularly Ruth Schonthal's "Totengesa nge" (LPI 106) and Katherine Hoover's Trio (LPI 103), I think no smaller word will do. No serious collection of contemporary music should be without these records.

In general, the music on Leonarda records is well-made and gets an excellent performance. There is a heavy emphasis on young, relatively unknown performers, undoubtedly for economic reasons, but the standards of musicianship are very high. And Leonarda offers repertoire to suit virtually any kind of classical music-lover. Those who care for baroque vocal music should hear the gracefully contrived cantatas of Elisabeth de la Guerre on subjects from the Bible and Greek mythology (LPI 109). For many, this record may provide a first encounter with the French baroque cantata, a charming form of music all too seldom heard. The well-wrought Mass by the record company's namesake, Isabella Leonarda (LPI 115), composed while Bach and Handel were still schoolboys, foreshadows some of the glories they were to produce while still preserving some cadences that recall the age of Monteverdi. Hildegard von Bingen, who shares that record with Leonarda, is a rare instance of a woman composer who has received fuller justice from another record company. Those who are interested in this extraordinary human being and her music in the medieval plainchant modes should hear the collection titled "A Feather on the Breath of God," performed by the Gothic Voices and available on Hyperion Records (A 66039).

From the 19th century, the "Lieder" Collection (LPI 107) presents two composers who deserve more detailed attention: Pauline Viardot-Garcia and, most particularly, Josephine Lang, who is represented by just enough songs to tantalize the listener. The recording by the Crescent Quartet (LPI 111) is as fresh and fascinating a collection of modern string quartets as I have heard on a single disc. It includes a late quartet by Amy Beach that shows that inventive artist still growing and developing at the end of her career.

Although the emphasis is on music by women, the catalogue includes some neglected music by men and a fresh interpretation of at least one classic by a male composer: Schubert's "Die Schoene Mu llerin."

This company is providing a distinguished service not only for a neglected class of composers but for music-lovers who are blessed with curiosity and adventurous tastes.

A few of Leonarda's most notable records are listed below: SONG CYCLES FOR SOPRANO PLUS: Kurt Weill: Frauentanz, Op. 10; Judith Lang Zaimont: Two Songs for Soprano and Harp; Ruth Schonthal: Totengesa nge. Edith Gordon Ainsberg and Berenice Bramson, sopranos; Sara Cutler, harp; Ruth Schonthal, piano; Bronx Arts Ensemble (Leonarda LPI 108) REBECCA CLARKE: Trio (1921). Suzanne Ornstein, violin; James Kreger, cello; Virginia Eskin, piano. KATHERINE HOOVER: Trio (1978). The Rogeri Trio. (Leonarda LPI 103) THE CRESCENT QUARTET: Lucie Velle re: String Quartet No. 3; Sarah W. Aderholdt: String Quartet; Ruth Schonthal: String Quartet; Amy Beach: Quartet for Strings, Op. 79 (Leonarda LPI 111) MUSIC FOR THE MASS BY NUN COMPOSERS: Isabella Leonarda: First Mass, Op. 18; Hildegard of Bingen: Kyrie. University of Arkansas Schola Cantorum (Leonarda LPI 115) FRENCH BAROQUE CANTATAS: Philippe Courbois: Dom Quichotte; Elisabeth Jacquet de la Guerre: Samson; Le Sommeil d'Ulisse. John Ostendorf, bass-baritone; Bronx Arts Ensemble Chamber Orchestra, Johannes Somary conductor (Leonarda LPI 109) LIEDER: Songs of Clara Schumann, Fanny Mendelssohn, Josephine Lang and Pauline Viardot-Garcia. Katherine Ciesinski, mezzo-soprano; John Ostendorf, bass-baritone; Rudolph Palmer, piano (Leonarda LPI 107)