DV Hardware published a review of the Noctua NF-P12 fan.

The NF-P12 is a new 120mm fan with several improvements for very silent operation. Noctua claims the NF-P12 has been specifically designed for
high-impedance applications such as processor coolers and watercooling rigs and features "psychoacoustic" improvements to make it less annoying to the human ear.

Noctua NF-P12 fan Review