Auralex's RC8 Resilient Channel is a specially formed, sturdy metal device that, when used to hang drywall (instead of just attaching the drywall to the studs or joists,) greatly improves the prevention of sound transmission through the wall or ceiling system.
RC8 Resilient Channel should be installed horizontally at the bottom and top of the wall, then every two feet or less in between. Up to two layers of 5/8" drywall and a layer of SheetBlok may be hung on the metal strips, including on a ceiling.
Eight Foot Strips
Auralex RC8 Resilient Channel - 8' Formed Metal Strips for Hanging Drywall - 24 Pieces