Steps:
1. Navigate to URL bar
2. Type "Cats are" or the start of some phrase
3. Start pressing down arrow

Cats are liquid
Cats are jerks
Cats are better than dogs
Cats are evil

In addition to the desired announcements, e.g. "Cats are evil search suggestion", additional text from at the end of the previously selected suggestion is sometimes spoke. Sometimes it is a single letter, or it can be a word or two.

Tech notes: I tried removing any AX notifications we fire but somehow AXValueChanged and AXSelectedTextChanged were still fired. I suspect it's probably due to one of those.