Answer: incomplete dominance
Explanation:
Incomplete dominance is also referred to as partial dominance or semi dominance. It occurs when the two forms of gene in a trait combine in such a way that one does not have a dominance over the other one. Therefore, there's a blend of both genes in the physical appearance of such organism.
Therefore, a low pitched male voices (RR) and a high pitched male voice (rr). Heterozygotes have a baritone voice is an example of incomplete dominance.