Or does he discuss sensory perception from another context.? — Arthur Rupel
The entire 'Transcendental Aesthetic' in the CPR is more or less dedicated to the question of sensory perception, which Kant generally groups under the name of 'sensibility' more broadly. A20/B34 lays out the broad strokes of how sensation figures in the architectonic:
"The capacity (receptivity) for receiving representations through the mode in which we are affected by objects, is entitled
sensibility. Objects are given to us by means of sensibility, and it alone yields us intuitions; they are thought through the understanding, and from the understanding arise concepts. ... The effect of an object upon the faculty of representation, so far as we are affected by it, is sensation. That intuition which is in relation to the object through sensation, is entitled empirical. The undetermined object of an empirical intuition is entitled appearance."
Importantly, for Kant, sensibility involves both what he calls 'matter' and 'form'. 'Form' involves the
a priori conditions of space and time, while 'matter' involves 'sensation in general':
"That in the appearance which corresponds to sensation I term its
matter; but that which so determines the manifold of appearance that it allows of being ordered in certain relations, I term the
form of appearance. That in which alone the sensations can be posited and ordered in a certain form, cannot itself be sensation; and therefore, while the matter of all appearance is given to us
a posteriori only, its form must lie ready for the sensations
a priori in the mind, and so must allow of being considered apart from all sensation." (A20/B34).
"Space and time are its [intuition's] pure forms, and sensation in general its matter. The former alone can we know
a priori, that is, prior to all actual perception; and such knowledge is therefore called pure intuition. The latter is that in our knowledge which leads to its being called
a posteriori knowledge, that is, empirical intuition. The former inhere in our sensibility with absolute necessity, no matter of what kind our sensations may be; the latter can exist in varying modes" (A43/B60).
So yeah, read the 'Transcendental Aesthetic' carefully, and you might find what you're looking for. There's alot there regarding the status of appearance, representation, and what can be known, especially in the bit titled "General Observations on Transcendental Aesthetic", (A42/B59).