Huron, D. (1989). Voice denumerability in polyphonic music of homogenous timbre. Music Perception, 6, 361-381.
Kashino, M., & Hirahara, T. (1996). One, two, many-Judging the number of concurrent talkers [Abstract]. Journal of the Acoustical Society of America, 99, 2596. doi: 10.1121/1.415287