A comparator of a synchronous SRAM includes: n1 EX-OR gates for detecting whether or not n1 signals included in an address signal inputted in a cycle and n1 signals included in an address signal inputted in the next cycle coincide with each other; and wired OR gates receiving output signals of the n1 EX-OR gates. The aim of the invention is to simplify the provision of information for diagnosing technical installations or technical processes. The membrane is spaced apart from the speaker and over an open end of the speaker housing.