An electroacoustic device intended to be used for the evaluation of hearing loss (audiometer function), the evaluation of hearing aids while worn to assure optimal amplification (real-ear measurement), and/or for other hearing aid analysis (functions as the hearing aid analyser to check its proper function when this is being fitted to the patient). It typically consists of a test box and a control unit that connect to a computer that runs application software to provide results and graphics (which may be stored in a database). The control unit may also be connected to other manufacturer's test boxes, or run as an audiometer or real-ear-measurement instrument without the test box.