refers to the atmospheric, background sound effect for the indistinct murmurings and buzz of voices in a crowd; extras in crowd scenes, in older films (or in radio), would be asked to murmur a phrase ('walla walla,' 'rhubarb,' 'peas and carrots,' or 'watermelon,' etc.) to create the sound of the crowd and to pretend that they were talking; see also foley artist, dubbing, and non-synchronized sound