Late in Saturday's Arabic-American musical fusion with Al-Bustan Seeds of Culture and the Crossing choir, West met East on a lofty plateau. A fugue, something associated with cerebral moments in J.S. Bach, unfolded with customary correctness but in a thoroughly Arabic melody.

The piece was Of Nights and Solace: Fantasia on Andalusian Muwash'sah Poetry by Syrian-born, Philadelphia-based composer Kinan Abou-afach, heard in its world premiere at Bryn Mawr College's Goodhart Hall, and was, to these ears, the moment when these two musical worlds came together on a new level. With microtonal Arabic scales, musical possibilities multiplied. The 12-tone western scales do good services, but are often engaged in the art of implying something beyond themselves. With 24 Arabic tones, implication isn't so necessary.

The concert, titled Words Adorned, also had the world premiere of Kareem Roustom's Embroidered Verses: Songs on Andalusian Poetry and solo songs featuring Nazareth-born singer Dalal Abu Amneh. All were compelling in their exotic ways, if muted by Goodhart's acoustics (a sound-focusing stage shell is badly needed). But this music requires time and repeated exposure for Western ears to parse. The 11th-century Andalusian poetry doesn't reveal its details immediately. Luckily, Al-Bustan's recording of the two new pieces will be issued in a few months.

On first exposure, both were full of emotionally charged vocal lines, especially as delivered by Abu Amneh, who appeared in a long white gown that enhanced her expressive gestures. The Crossing sang with startling accuracy and emotional comprehension under Donald Nally. In one passage, the soloist was heard against a fluffy, microtonal bed of delicate harmony.

Musical rhetoric was usually Arabic, but framed and sustained over long spans by Western techniques. Recitative-like passages used the Crossing as accompanying poetic commentary. Gray areas between melodically serpentine Arabic chant and spoken word were artfully explored. Roustom's piece was particularly adept at sidestepping musical expectation with gestures that would suggest one direction and then hang a left. Pitch-defying glissandos had much greater expressive purpose than in strictly Western music. And when the Al-Bustan's Takht Ensemble let loose with an extended improvisation near the end of the concert, you realized how much this group crackles.