To cite tuneR in publications use:

Uwe Ligges, Sebastian Krey, Olaf Mersmann, and Sarah Schnackenberg (2013). tuneR: Analysis of music. URL: http://r-forge.r-project.org/projects/tuner/.

Corresponding BibTeX entry:

  @Manual{,
    title = {{tuneR}: Analysis of music},
    author = {Uwe Ligges and Sebastian Krey and Olaf Mersmann and Sarah
      Schnackenberg},
    year = {2014},
    url = {http://r-forge.r-project.org/projects/tuner/},
  }