a pitch too cerebral?

Lazarakis   Sat Jul 29, 2006 1:03 am GMT
1.
"Mirror, mirror on the wall, who among us is fairest of all?" she said.
Bianca straightened up and listened, as if the mirror might answer. If it did, it was in a pitch too cerebral or too hushed for Bianca to hear.

What does "cerebral" mean in this sense?

2.
I will not grant that privilege to any.
I don't possess credentials bright enough
To vouchsafe anyone passage to paradise.

What does "bright" mean when it's used to describe credentials?