PRODUCTION AND DETECTION OF SPEECH ERRORS IN SILENT, MOUTHED, NOISE-MASKED, AND NORMAL AUDITORY-FEEDBACK SPEECH

In this study subjects had to report their errors during the speeded p roduction of tongue twister sentences in one of four speech conditions : silent, mouthed, noise-masked, and normal auditory feedback speech. In contrast to the other three conditions, silent speech comprises spe ech planning but no articulation. Error monitoring in the normal audit ory feedback condition may occur both by means of an inner speech (pre -articulatory) loop and by means of auditory feedback, whereas in the other conditions only the first channel is available. The results show ed that reported error rates were roughly equal in the silent, mouthed , and noise-masked condition, with an increase in the normal auditory feedback condition. Significantly more phonemic-sized errors and disfl uencies were reported with auditory feedback, whereas word errors were less frequent. Notwithstanding the differences with respect to error size, report rates for the individual error categories (e.g. anticipat ions, perseverations, substitutions, etc.) did not differ notably for the four conditions. Errors typically occurred at the same points acro ss speech conditions. These results suggest that speech planning proce sses are similar in the four speech conditions. Moreover, actual motor execution (i.e. articulation) does not appear to be an important cont ributor to the error events under study. The main difference between c onditions can be attributed to the available monitoring channels.