Who manufactures the quietest AC units?

As of 2014, Consumer Reports listed the Friedrich brand as offering the quietest air conditioner unit available. More specifically, the Friedrich Kuhl SQ05N10B is the model that is listed as the quietest out of all brand units that were tested.

Noise Help, a website committed to the discovery of quiet products, lists the brand Friedrich as a whole when giving the vote for quietest air conditioning unit available. The Friedrich website lists the noise-reduction design as imperative to the air conditioning unit's ability to maintain the quietest working motor that is sold on the market, as of the summer of 2014.