As part of a beginning study on speech adaptation to dental appliances, four young adults were fitted with an experimental alveolar-palatal acrylic appliance similar to an orthodontic retainer. They wore the appliance for one week in an attempt to learn to speak normally with it. The appliance causes phonetic distortions in the beginning, and a slight voice quality change. The question is whether these speech alterations, both in the beginning and after one week's adaptation time, are sufficient to affect a listener's judgment of the speaker's identity. Paired voice samples representing different persons, the same person with and without the appliance, and the same person with or without the appliance were judged by phonetically naive persons. Judges were asked to indicate whether each pair was spoken by the same person or different persons, and in addition to indicate their confidence in the judgment. Results are reported in terms of the number and types of errors the judges made. [Supported by a University of Maryland Faculty Research Award.]