To cite soundgen in publications use:

Anikin A (2019). “Soundgen: An open-source tool for synthesizing nonverbal vocalizations.” Behavior Research Methods, 51(2), 778–792. doi:10.3758/s13428-018-1095-7, https://doi.org/10.3758/s13428-018-1095-7.

Corresponding BibTeX entry:

  @Article{,
    title = {Soundgen: An open-source tool for synthesizing nonverbal
      vocalizations},
    author = {Andrey Anikin},
    journal = {Behavior Research Methods},
    year = {2019},
    pages = {778--792},
    volume = {51},
    number = {2},
    doi = {10.3758/s13428-018-1095-7},
    url = {https://doi.org/10.3758/s13428-018-1095-7},
  }