The synthetic syllables used in the experiment were produced by Francisco Lacerda at the Department of Linguistics, Stockholm University, using parameter synthesis. Formants 1, 3 and 4 are the same in all stimuli, only the second formant is different in the various stimuli. The diagram shows in a summary form all 20 stimuli.
This test is only meant as a demonstration. In a real experiment, each subject is presented with many more repetitions of each stimulus in order to minimise error due to temporary lapse of attention, or simply pressing the wrong button. Scientific results are also often presented as averages of the results for a whole group of subjects. If the experiment, presented here as a simple test, is performed with a group of subjects, the results become clearer and more reliable. A typical result of such an experiment is shown here.