in an exemplary embodiment , for testing the chronological resolution of hearing , acoustic signals are supplied to the ear to be tested via an earpiece and consist of a test tone which can be interrupted and of a masking sound which can be modulated , their frequency and amplitude level being adjustable . complicated measures are necessary for the measurement of the so - called listening threshold period pattern in order to present a complete pattern for identifying the chronological resolution of the hearing . in contrast , the disclosure provides an uncomplicated measuring device which is also easy to operate and with which the maximum and the minimum of the listening threshold period pattern or , respectively , their difference can be determined . to this end , the disclosure provides a device with channels generating respective sound signals , each of the channels having its own generator . whereas the first generator is designed in the manner standard given electro - acoustical audiometers , that for the second channel has a noise generator whose output is modified by means of frequency band selection filters to provide a noise band with a mean frequency which can be matched to changes in the selected frequency of the first channel , and whose output amplitude level can be increased to a suitable value in comparison to the quiescent hearing threshold level of the test tone . the disclosed device is particularly suitable for use in testing hearing .