Can tension in nontonal music be expressed without dynamic or rhythmic cues? Perceptual theories of tonal harmony predict that psychoacoustic roughness plays an important role in the perception of this tension. We chose a set of orchestrated chords from a nontonal piece and investigated listeners' judgments of musical tension and roughness. Paired comparisons yielded psychophysical scales of tension and roughness. Two experiments established distinct levels of these two attributes across chords. A model simulation reproduced the experimental roughness measures. The results indicate that nontonal tension could be perceived consistently on the basis of timbral differences and that it was correlated with roughness, the correlation being stronger as the perceptual salience of other attributes (such as high-pitched tones or tonal intervals) was reduced.