To cite tuneR in publications use:

Uwe Ligges, Sebastian Krey, Olaf Mersmann, and Sarah Schnackenberg (2018). tuneR: Analysis of Music and Speech. URL: https://CRAN.R-project.org/package=tuneR

Corresponding BibTeX entry:

  @Manual{,
    title = {{tuneR}: Analysis of Music and Speech},
    author = {Uwe Ligges and Sebastian Krey and Olaf Mersmann and Sarah
      Schnackenberg},
    year = {2018},
    url = {https://CRAN.R-project.org/package=tuneR},
  }