perceptible

This term describes a threshold of awareness where a stimulus becomes strong enough to be registered. It carries a neutral, objective tone, often used in scientific or technical contexts to describe a measurable change that is just barely detectable. While it can refer to physical sensations like smell or sound, it frequently describes abstract shifts in mood, tension, or logic. It suggests a transition from the invisible or unnoticed to the recognized, emphasizing the act of detection rather than the intensity of the experience.