Yes and no... Caster can see or feel the weave or the forming of spells as their being casted, this is like a tingling or extra sensory caster have, even more so IF they have a detect magic spell active... Removing voice, gestures and components is to avoid non-casters ability to pick up on them, handy when you use magic in crowded settings, or to use spells when for example a silence spells, or tied...
