Where does clarity collide?

In philosophy, clarity is a mark of knowledge: Descartes held that whatever we perceive clearly and distinctly can be affirmed as true, a clear idea being one present and open to an attentive mind and a distinct idea one sharply cut off from all others. His Meditations on first philosophy makes clear-and-distinct perception the criterion that rebuilds knowledge after doubt. The referent is an epistemic quality of ideas or perceptions, a different construct from a graded property of a gem or a measured ratio in a concert hall, sharing only the meaning of being unclouded.[1]

Unit

The degree to which an idea is present and distinct to the attentive mind

Recovery means

Not applicable

Measured by

Not a measured quantity; assessed philosophically as the clearness and distinctness of a perception

In gemology, clarity is a graded property of a gem: how free it is of internal inclusions and surface blemishes, judged for a diamond on a scale running from flawless down through very slightly included to included, usually under ten-power magnification. Webster's Gems and Read's Gemmology set out the inclusion types and grading conventions that fix a stone's clarity. The referent is a visual quality grade tied to a stone's flaws, unrelated to the clearness of a philosophical idea or the acoustic clarity of a room except by the shared image of clearness.[2][3]

Unit

The clarity grade reflecting the size, number, and visibility of inclusions and blemishes

Recovery means

Not applicable

Measured by

Graded by trained observation, typically at 10x magnification, against a defined clarity scale

In room acoustics, clarity is a measured ratio: the clarity index (C80 for music, C50 for speech) compares the sound energy arriving in the first 80 (or 50) milliseconds after a sound to the energy arriving later, in decibels, so a higher value means notes or words stand out rather than blur into reverberation. Kuttruff's Room acoustics defines the index and relates it to the room's impulse response. The referent is a quantitative acoustic parameter of a space, a wholly different construct from a gem grade or a philosopher's clear idea.[4]

Unit

The decibel ratio of early to late arriving sound energy in a room

Recovery means

Not applicable

Measured by

Computed from the room's measured impulse response as the ratio of early to late energy (C80 at 80 ms, C50 at 50 ms)