Insulation materials have traditionally been applied to the interior or exterior of duct for a combination of purposes, including thermal efficiency, condensation control, and noise control. Of these, effective noise control is by far the most challenging. It is important to remember that a conventional duct liner and, to an even lesser extent, duct wrap, will only resolve a portion of the noise issues in any building. An effective noise attenuation strategy begins at the design stage and utilizes a combination of methods including mechanical layout, vibration isolation, and duct insulation. Duct insulation, of course, is available in a variety of materials. This paper explores the ability of elastomeric foam duct insulation to resolve common low frequency noise problems and challenges the notion that elastomeric foam lags behind fibrous materials in terms of sound attenuation.