A gavel strikes against a small piece of wood called a "sound block." It can also be referred to as a "sounding block." Gavels and sound blocks are often used by judges or presiding officers during legal proceedings or meetings in order to signal order or call attention.
Striking a sound block can also be used to begin a legislative session or to put a motion into effect. An auctioneer may use a gavel and sound block to signal the acceptance of a final bid. Gavels and corresponding sound blocks are commonly made of walnut and oak. Other materials include rosewood, acrylic and glass.