Influences of pellet markers on speech production behavior: acoustical and perceptual measures

Peri- and intraoral devices are often used to obtain measurements concerning articulator motions and placements. Surprisingly, there are few formal evaluations of the potential influence of these devices on speech production behavior. In particular, the potential effects of lingual pellets or coils used in x-ray or electromagnetic studies of tongue motion have never been evaluated formally, even though a large x-ray database exists and electromagnetic systems are commercially available. The x-ray microbeam database [Westbury, J. "X-ray Microbeam Speech Production Database User's Handbook, version 1" (1994)] includes several utterances produced with pellets-off and -on, which allowed us to evaluate effects of pellets for the utterance, She had your dark suit in greasy wash water all year, using acoustic and perceptual measures. Overall, there were no acoustic or perceptual measures that showed consistent effects of pellets across speakers, but certain effects were consistent either within a given speaker or in direction across a subgroup of the speakers. The results are discussed in terms of the general goodness of the assumption that point parameterization of lingual motion does not interfere with normal articulatory behaviors. A brief screening procedure is suggested to protect articulatory kinematic experiments from those individuals who may show consistent effects of having devices placed on perioral structures.