Hearing aid fitted with a central processing unit (1) having peripherals (3E, 3A) connected to its input and output respectively. Each peripheral includes an identification unit (5) having an the output connected to a first input of a comparator (9). A second input of the comparator is connected to a read-only identification memory (11) containing identification features of the peripherals. An output of the comparator drives a configuration memory (15). As a result, the hearing aid self-identifies its current configuration based on the identification of the peripherals.