Notes on Plotting Software
Several dedicated plotting programs are available. Our goal here is not to comprehensively survey the competing products, but is instead briefly to highlight some of the most commonly used plotting tools. Many of these can actually be used interchangeably, since, as described above, conventional F1~F2 vowel plots are simply scatter plots with the axes flipped, and most graphing tools can generate scatter plots without difficulty.
Spreadsheet applications, in particular Microsoft Excel, are widely used for managing and analyzing vowel data. Through Excel you can quickly generate rough plots of your data as you work, and these plots will automatically update if you make changes to your data. More specialized applications allow the creation of publication-quality graphics. Origin and SigmaPlot, for example, will generate excellent vector-based plots. MagicPlot is available for free to students, though the functionality of that version is limited; only the full version will allow you to create vector images. Some researchers also use statistical and mathematical applications such as SPSS - now called PASW - and MATLABfor plotting, and plotting libraries (matplotlib, PyX, MayaVi) in the programming language Python, are designed for the creation of publication-quality 2D and 3D graphics. Increasingly, the statistical programming language and environment R is used to manipulate and plot vowel data. With R, the graphing possibilities are near limitless; this potential is very much easier to harness now that menu-driven graphical user interfaces such as R Commander or R Studio are available for R, the command-line format of which is likely to have been offputting for many novice users.
Specialized sociophonetic software is also available for both vowel plotting and normalization. Praat, the widely used phonetic software, can be used to generate plots using plug-ins such as Akustyk (Plichta 2006). Plotnik is the plotting software developed by William Labov and used for the The Atlas of North American English (ANAE, Labov, Ash and Boberg 2006). The VOIS3D (Vowel Overlap Indication Software - 3D) package, written in MATLAB but available as a standalone tool, is discussed in Chapter 8 ('Analyzing vowels'). Finally, NORM (Thomas and Kendall 2007) is a web-based vowel plotting and normalization suite written in R. All of the packages mentioned in this paragraph are free.