be intelligible

See: cohere
References in classic literature ?
You are an extremist, you know, dear, and what may be intelligible to you may not be intelligible to the rest of us.
If he had married a fool, his conduct would be intelligible enough.
There is no explicit reference to intelligible matter here, but given that forms are intelligible objects "the matter of the form" will be intelligible matter.
But the rate should be intelligible to the audience and slow enough not to reveal nervousness.