A tract is a literary work and, in current usage, usually religious in nature. The notion of what constitutes a tract has changed over time. By the early part of the 21st century, a tract referred to a brief pamphlet used for religious and political purposes. Tracts are often either left for someone to find or handed out. However, there have been times in history when the term implied tome-like works. A tractate, a derivative of a tract, is equivalent in Hebrew literature to a chapter of the Christian Bible.
Wolfe et al (Vocal tract resonances in speech, singing, and playing musical instruments) say in the abstact:
Now, I recently got interested in the role of the vocal tract in achieving pitch accuracy. Regarding this aspect Wolfe et al discuss it in the case of wind instruments but not in...