Control of the Jaw in Relation to Stress in English

Current evidence, although fragmentary, suggests that, with high degrees of stress, upper articulators exhibit more movement from natural or prior positions but move no faster. The result is usually increased segment duration. These relationships were investigated in the case of jaw movement. Movement data were obtained by excitation of a photocell by a small light attached to the jaw. Electromyograms were also recorded from muscles controlling the jaw. Movement parameters and relations between electromyograms and movement were obtained by computer. A number of stress environments were examined including noun and verb pairs differing only in stress. In preliminary results, the aforementioned relations between stress and segment duration and amount of articulator movement were replicated. However, contrary to expectations, heavier stresses were usually accompanied by higher rates of jaw movement. Furthermore, studies of the dynamic relations between jaw movements during the entire syllable suggest that for...