Advertising drum
The phrase "(for someone or something) beating the drum (beating) the drum" means to carry out extensive advertising measures.
Word origin
The drum was originally referred to the big drum in the 17th century, with the mercenaries were recruited for military service. Drums and other instruments were used in public places to draw attention to the mercenary service . The advertising trummels were strongly stirred up (1681).
A transfer to the advertising industry did not take place until the 20th century.