Suspension bridge types simple suspension bridges and suspended-deck suspension bridges, and excludes self-anchored suspension bridges. Some suspension bridges are of unusual hybrid types. Among these are suspension bridges that have an "intermediate deck". These bridges have a portion of deck that resembles an underspanned suspension bridge. Some of the earliest suspended-deck suspension bridges were of this type, and they continue to be constructed. Examples constructed in the 20th century include a viaduct over the river Oberargen near Wangen, Germany. A span of the viaduct has a cable support below the deck, with one end of the cable anchored at a pier and the
Acoustic suspension acoustic suspension, with a separate, sealed air-space, even if the woofer itself is not. One notable exception to this was the Sonus Faber Stradivari Homage which uses a ported enclosure for the midrange. The two most common types of speaker enclosure are acoustic suspension (sometimes called pneumatic suspension) and bass reflex, so they are worth comparing. In both cases, the tuning affects the lower end of the driver's response but above a certain frequency, the driver itself becomes the dominant factor and the size of the enclosure and ports (if any) become irrelevant. In general, acoustic suspension systems (driver +