However, there are two closely related concepts that might be what you're thinking of:
1. Vowel Chart (or Vowel Quadrilateral): This is a diagram used in phonetics to represent the different vowel sounds in a language. It is typically a two-dimensional chart with height (high vs. low tongue position) on the vertical axis and backness (front vs. back tongue position) on the horizontal axis. The vowels are plotted on the chart based on where the tongue is positioned in the mouth when producing the sound.
2. Vowel Trapezoid: This is another term used to describe a vowel chart. It can be used to show the relationship between the vowel sounds within a language.
To understand these better, think of it like this:
* Imagine you're holding your tongue flat in your mouth.
* Height: Move your tongue up towards the roof of your mouth for high vowels (like "ee" in "see") and down towards your throat for low vowels (like "ah" in "father").
* Backness: Move your tongue forward for front vowels (like "ee" in "see" or "i" in "machine") and back for back vowels (like "oo" in "moon").
If you can provide more context about where you encountered the term "vowel triangle," I might be able to give you a more specific and helpful explanation!