sound block

or sound·ing block

[ sound blok or sound-ing blok ]
/ ˈsaʊnd ˌblɒk or ˈsaʊnd ɪŋ ˌblɒk /

noun

a small block of wood for rapping with a gavel.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019