Silencing and separation in a cold-air, essential-oil, diffuser apparatus and method pass flow through a channel having comparatively high aspect ratios of length to thickness and width to thickness. Curved, tapered, non-parallel, and quasi random surfaces reduce probability and power of resonant frequencies. Offsetting flow through a channel is followed by impingement against an obstructing surface, redirection elsewhere within a drift (separation) chamber, and exiting through a smaller, and differently oriented exit port. Silencing is improved by changes of cross-sectional area creating high-pass and low pass acoustic filters, changes of direction, and absorption of acoustic energy in fluid-droplet-laden air.
