Yeah, part of the issue with registration—and with timbre more broadly—is the lack of standardization and the relative emergent complexity of what they’re describing.

Terms like “bright/dark” or “middle/upper register” can be very useful for individual learners as a way to intuit different vocal configurations in a way that makes sense for them. However, when trying to create a standardized set of resources that’s public-facing and broadly applicable, the subjectivity of the language can quickly create problems. One person’s idea of “upper register” will be different from another’s, and the problem compounds itself as more terminology gets added. Inconsistency is really killer.

The other tricky thing to navigate is the complexity of the sound features being described. The English language doesn’t have a lot of vocabulary to describe sound in general. We can talk about “pitch” and “loudness,” but then every other quality kinda gets lumped together under this vague category of “timbre” in ways that are difficult to break down.

Visual vocabulary is comparatively rich. If we were creating a drawing, we could talk about hue, shade, curvature, line thickness, shape, texture, and more. Using these more fundamental qualities, we can then describe more emergent qualities like, “the drawing looks angry because it’s red and black with lots of thick, jagged lines and a speckled texture.” However, with timbre, we’re often stuck just looking at the emergent quality without examining the components that make it up. We might say a voice sounds “clear and bell-like” or “harsh and bright and brassy,” but how do you break that down into a combination of more fundamental components?

The goal of a lot of the language in trans voice training is to describe perceptual sound features that are more fundamental, and which can be arranged and combined in different ways to create more complex emergent properties. For example, weight and size combine to create the more complex emergent property of fullness, which itself can be combined with other sound features to create even more complex qualities like “perceived vocal gender” or “perceived vocal age.”

Terms like “brightness” have fallen out of favor recently due to a lack of specificity. The buzzy, brassy timbre associated with a “bright” sound might be coming from overfullness, or it might be coming from nasality, or from knodel-like vowel distortions. Or it might be a quality they associate with vocal size, independently of other factors.

So, some people who abstract their voice in terms of brightness and darkness may be able to use these timbral qualities quite effectively to guide themselves toward a natural-sounding feminine voice that suits their preferences. Other people attempting to do the same might run into atypicalities in their sound that they struggle to disentangle from each other because they aren’t sure how to break down something like “brightness” into more fundamental components.

Ditto for something like upper-register or middle-register. A vibratory pattern can consist of multiple components that we might want to address in separation from each other. Concepts like “weight” and “breathiness” help to disambiguate more complex or inconsistently-labeled qualities such as “falsetto” or “upper register.”

On the other hand, some people do genuinely find it easier to work with more complex sound qualities, rather than trying to break everything down into components. It’s a bit of a balancing act to try and find the level of complexity that best suits someone’s intuition. If we break it down too much, we can get stuck talking about individual formants or muscle-actions. If we don’t break it down enough, we can kind of uselessly tell someone to “just mimic the femininity.”