To cite soundgen in publications use:

Anikin, A. (2018). Soundgen: an open-source tool for synthesizing nonverbal vocalizations. Behavoir Research Methods, 1-15. 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 = {2018},
    pages = {1--15},
    issn = {1554-3528},
    doi = {10.3758/s13428-018-1095-7},
    url = {https://doi.org/10.3758/s13428-018-1095-7},
  }