Richard James (a k a Aphex Twin, AFX, Polygon Window, the Dice Man) says he crafts techno symphonies in his head while he sleeps, but judging from the unsettling nature of many of his songs, it appears he doesn't slumber too peacefully.

Aphex Twin's Selected Ambient Works Vol. II is the two-disc follow-up to the import-only Selected Ambient Works 85-92, the album that established the Cornwall, England, native as the pioneer of ambient techno, a musical style that converts the energized electrobeats and keyboard surges of dance-floor techno into slower, more tranquil sound washes.

While many of his disciples have done little more than propel New Age atmospheres into the computer age, producing comforting but often emotionless elevator music, James has used the medium to confront his shadowy demons, exploring realms of spooky, textured sound.

On Vol. II, James turns away from the glut of soulless techno by stripping away its base properties, focusing more intently on mood than on rhythm and melody. Most of the songs rely on eerie synth effects layered within sparsely repeated or sustained notes and blips that pulse like distant stars. Few use beats. Indeed, it's the absence of beats that makes the music so strange and haunting, and when beats do surface, they serve to accent a tone rather than sustain a tempo.

Drawing inspiration from the early ambient work of Brian Eno and the minimalism of John Cage, James has created a riveting, experimental record that demands listener interaction. Each of the 23 untitled songs outline such troubled emotions as melancholy, fear and confusion, but the music is too inchoate to paint a full picture.

Many of the tracks are so subdued that any incidental noises that drift into earshot (car horns, bird song, chatter) become unconsciously integrated into the mix, and the sound effects are so cryptic that like a Rorschach test, interpretations are entirely subjective. With a bit of imagination, the opening song could evoke a gurgling baby on a beach as the tide comes in, while the 22nd track might suggest a broken jack-in-the-box that opens to reveal a hideous, laughing troll.

Surreal, otherworldly and occasionally nightmarish, Selected Ambient Works Vol. II provides a visionary perspective on ambient electronic music. Close your eyes, drift to sleep, start to scream. (RS 685)

JON WIEDERHORN