The term "single voices" can be replaced with a variety of synonyms. One such synonym is "solitary voices," which implies a sense of solitude or being alone. Another synonym is "individual voices," which emphasizes the uniqueness of each person's voice. "Solo voices" is also an option, which suggests a single performer or vocalist. "Singular voices" is another synonym that conveys the importance and distinctiveness of each voice in a group. "Isolated voices" implies separation or detachment from others. "Unaccompanied voices" suggests that the voices are not accompanied by any other instruments or singers. Overall, there are many options to choose from when seeking synonyms for "single voices".