Since its inception in the fall of 1977, The Washington Bach Consort's goal has been to perform the complete instrumental and vocal works of Johann Sebastian Bach. Yesterday afternoon at Washington Cathedral, the group, under the direction of J. Reilly Lewis, presented its latest installment of this massive undertaking: the master's liturgical vocal compositions from his Leipzig period.

The acoustics of the cathedral leave something to be desired; vocal and instrumental forces seem to vie for dominance, rather than blend congenially. To compound matters, audience noises are so amplified that an innocent cough echoes like a distant gunshot, doing further injustice to the music.

In spite of these conditions, the Consort triumphed, often resoundingly. Bach's Cantata No. 10, "Meine Seel erhebt den Herren" ("My soul exalts the Lord"), succeeded on the strengths of the nonchoral sections, particularly in the Recitativo and Duet portions that featured the splendid tenor Stanley Cornett. The two motets for double chorus, "Komm, Jesu, komm" ("Come, Jesus, come") and "Der Geist hilft unser Schwachheit auf" ("The spirit helps us overcome our weakness"), were much better balanced overall; the words were easier to follow, and the vocalists' realization of Bach's ingenious part-writing and powerful word-painting achieved the desired result--to intensify the myriad affections expressed in the texts.