David Huron and Deborah Fantini
Music Perception, Vol. 7, No. 1 (1989) pp. 43-48.
Experimental evidence has shown that entries of inner voices are more difficult to perceive than entries of outer voices in multivoiced music. A study of voice entries in 75 fugues by J. S. Bach shows no significant avoidance of inner-voice entries in three- and four-voice textures. However, in the case of five-voice textures, Bach does demonstrate a significant reluctance to have a voice enter in an inner-voice position. This finding is consistent with the hypothesis that Bach endeavors to minimize perceptual confusion in his polyphonic works as the textural density increases.
Full text.