This is often what happens in a band or music class. If the musicians have no had enough time to practice, or have been slacking off, the instructor/teacher might assign them time to nurddle. Nurddle: the act of playing an instrument aloud without structure, (ie) playing by yourself, not with others. Nurddling : the act of the nurddle. Nurddler: the person(s) making the sound.
Between playing tests, our teacher gave us nurddle time to practice.