Abstract: An interface unit for measuring instruments, such as audiometers, which are controlled by a computer, the interface unit being as cost-efficient as possible and setting minimum requirements for the computer hardware and software. This is achieved in that the lines (17 to 19) of the interface unit that are connected to the computer contain d-c isolating couplers (17.1 to 19.1) and are respectively connected with individual decoders (13 to 15) which, in turn, are connected to memories (7 to 9). Control lines lead from these memories to the measuring modules (1 to 3) of a measuring instrument. Such a measuring instrument is usable, in particular, as an audiometer or for establishing the optimum adjustment of a hearing aid to compensate certain hearing impairments.