The Dohm Uno is an entry-level sound machine and offers the soothing fan-based sound at an affordable price. The Uno is single-speed (hence uno) and has an adjustable collar to allow you to control the tone and volume of the sound. The Dohm Classic or Dohm Natural Sound offers two speed options - a high and low setting. The Dohm Uno's sound is comparable to that between the high and low setting of the Dohm Classic or Dohm.