A METHOD FOR MONITORING AND DETECTING IF HEARING INSTRUMENTS ARE CORRECTLY MOUNTED

A binaural hearing aid system comprising left and right hearing instruments adapted to be located at or in left and right ears, respectively, of a user, each of the left and right hearing instruments comprises a) a BTE-part configured to be located at or behind an outer ear of the user, the BTE-part comprising a housing; b) an acceleration sensor configured to measure acceleration in at least two directions relative to the housing of the BTE-part and to provide acceleration data indicative thereof. At least a first one of the left and right hearing instruments comprises a transmitter being configured to allow transmission of acceleration data from the acceleration sensor to the second one of the left and right hearing instruments, and at least a second one of the left and right hearing instruments comprising a receiver being configured to allow reception of the acceleration data from the acceleration sensor of the first one of the left and right hearing instruments. At least the second one of the left and right hearing instruments comprises a controller configured to detect whether or not the left and right hearing instruments are correctly mounted in dependence of a similarity measure, e.g. a correlation measure, between said acceleration data provided by the left and right hearing instruments. A method of operating a binaural hearing aid system is further disclosed.