The research reports that describe the use of these sounds are:
Remez, R. E., Van Dyk, J. L., Fellowes, J. M., & Rubin, P. E. (1998). On the perception of qualitative and phonetic similarities of voices. In P. K. Kuhl and L. A. Crum (Eds.) Proceedings of the 16th International Congress on Acoustics and the 135th Meeting of the Acoustical Society of America, Volume 4 (pp. 2063-2064). New York: Acoustical Society of America.
Fellowes, J. M., Remez, R. E., & Rubin, P. E. (1997). Perceiving the sex and identity of a talker without natural vocal timbre. Perception & Psychophysics, 59, 839-849.
Remez, R. E., Fellowes, J. M., & Rubin, P. E.
(1997). Talker identification based on phonetic information. Journal
of Experimental Psychology: Human Perception and Performance, 23,
651-666.