IN many restaurants, pubs and shops there is the incessant thumping of a drum. This noise seems to be called "background music", despite the fact that it dominates the foreground and has none of the characteristics of music, though it is sometimes possible to hear howls and grunts above the drumming.

It is surprising that proprietors do not simply install a piece of out-of-balance machinery to provide the necessary thumping noise. This would save them the cost of a Performing Rights Licence and would irritate their customers just as effectively.

Dr PM Dryburgh, Edinburgh EH10.