[Note added 1-09-10: S. E. Hyman, writing in 1952, does have a point in noting John Crowe Ransom's positive assessments of Empson (297-98), but he overstates things when he claims a substantial influence of Empson on the "Southern school." Hyman says, for example, that Understanding Poetry "makes frequent reference to Empson" (298), but that is certainly not true of the first edition (1938): the only critics mentioned there are F. W. Bateson, L. C. Knights, Chard Powers Smith, Ransom, and I. A. Richards. As Hyman notes, Empson's views on Thomas Gray's Elegy are given a page, but only in the context of a (critical) assignment (Brooks and Warren 1938, 514-515; Hyman, 299). Hyman is apparently referring to a later edition, but I find little if any change in the one I have in hand: the revised "Complete Edition," published in 1950. Most significantly, there is no mention of Empson at all in the newly added essay "Ambiguity, Added Dimension, and Submerged Metaphor" (1950, 571-591). The relationship of Brooks and Empson is probably best described as that of rival disciples of Richards. Hyman himself (who was obviously an Empson advocate) summarizes their jousting in rival reviews (298-99).]
Unfortunately, Empson's categories don't translate easily to music--the distinctions between them can be subtle, requiring the support of the capacities of language, the sorts of distinctions that are either far more difficult to grasp in music or may simply not be there. Sylvia Imeson's attempt at a one-on-one mapping of the seven types onto music fell short; one notes that her work has rarely been cited since in the burgeoning literature on irony, paradox, metaphor, and humor in music.
It may also be true that the highly ritualized manner by which historical European musics are heard (and have been heard for well over 100 years now) has obliterated the kinds of gestural and topical understandings that would be fine enough to enable reading/hearing by means of ambiguity on Empson's terms. Until those understandings are reconstructed (as in the ongoing project of Robert Hatten, for example), it may be impossible to chart them against one another in systems of double meaning.
References:
Empson, William. Seven Types of Ambiguity. London: Chatto and Windus, 1930.
Imeson, Sylvia. "The time gives it proofe": Paradox in the Late Music of Beethoven. New York: Peter Lang, 1996.
Hatten, Robert. Musical Meaning in Beethoven: Markedness, Correlation, and Interpretation.Bloomington: Indiana University Press, 1994.
Hatten, Robert. Interpreting Musical Gestures, Topics, and Tropes: Mozart, Beethoven, Schubert. Bloomington: Indiana University Press, 2004.
Brooks, Cleanth, and Robert Penn Warren. Understanding Poetry: An Anthology for College Students. New York: Henry Holt, 1938.
Brooks, Cleanth, and Robert Penn Warren. Understanding Poetry. Complete Edition. Revised. New York: Henry Holt, 1950.
Hyman, Stanley Edgar. The Armed Vision: A Study in the Methods of Modern Literary Criticism. New York: Knopf, 1952.