LaTeX
If you use a Mac, I recommend MacTeX, which will give you everything you need. Likewise, MiKTeX is what I recommend for Windows.
Some of my preferred packages for linguistics are:
- Qtree - Good for drawing simple trees.
- tikz-qtree - Like Qtree, but more powerful.
- PST-Jtree - Better for larger, more complex trees.
- tipa - IPA for LaTeX.
- gb4e - For typesetting examples and interlinear glosses.
Most of these packages should be come installed with whichever distribution you choose. However, if they are not, then they can be found via the links provided.
A good start is the LaTeX for Linguists page. If you want to get serious, I highly recommend the Ling-TeX mailing list.
This is a spectrogram:
