Feedback in Speech Production: an Ecological Perspective

Abstract

One of the most spectacular findings in recent experimental phonetics is the great ability of experimental subjects to compensate for interference with the operation of the speech apparatus. There has been a number of studies of the effects of placing bite blocks of various sizes between the teeth and asking the subject to produce steady state vowels immediately afterwards. These studies have been unanimous in showing that even with bite blocks 22-25 mm in height, subjects were able to produce vowels with appropriate formant frequencies, as early as the first pitch period of phonation. The results of the bite block studies appear to demand the use of peripheral somatic sensory feedback to inform the control mechanism about the state of the articulators prior to the generation of control signals compensating for that state. It is argued that successful speech observed under bite block conditions, and also under a wide range of self imposed postural constraints, which typically precede and accompany ordinary speech, requires a speech control mechanism which uses (both off-line and on-line) peripheral somatic sensory feedback.