I got some of the Cree 60w soft white dimmable bulbs to try in our dining room fixture - they sing.
The Mrs. wasn't pleased with the stark contrast to the warm cfl's she's been using, but the noise was highly perceptible from the single bulb I tried. Didn't matter if it was dimmed or full output - it had a pitch to it that was an absolute no-go. I'm near certain if I'd put all 4 in, the neighborhood dogs would start singing back. It was pretty bad. They got returned.