I’d like to address the term “voicing,” which I think is often misunderstood. Here’s my best definition:
Voicing refers to the relative size of the oral cavity, which can change depending on the position of the back of the tongue.
There are a number of other terms that are used to describe this same concept in woodwind playing. I don’t take issue with any of these terms individually, and I think that as a teacher it’s useful to have a variety of possible ways to explain this concept. (These terms can become problematic, however, when they are used in opposition to each other: “Open up, and blow cooler air.”)
Here are some examples of ways of describing voicing. I consider the terms in the left column all to be descriptions of the same thing, and those on the right to be likewise equivalent to each other.