Instrumentation for automatic two-interval forced-choice audiometry

In a two-interval forced-choice (2 IFC) audiometric test the observer has to decide which of the two intervals contains an auditory stimulus. The paper discusses the basic design philosophy and principle of operation of a hard-wired experimental facility for automatically locating specific points on the psychometric function for this type of test. Variable intervals and stimuli frequencies and means of recording and analysing the responses are provided.