Since pneumotachograph masks are commonly used in studies of speech breathing, the purpose of this study was to measure the differences in respiratory volumetric and frequency measures during speech under two conditions: with and without a circumferentially vented pneumotachograph mask coupled to the face. Thus we sought to identify whether changes in breathing patterns occur with the use of a specific face mask, because these patterns are accepted as representative of normal speech breathing. Subjects were 10 normal-speaking women, each of whom produced a syllable train and a connected speech task, both at comfortable intensity levels. Respiratory measures were made using linearized magnetometers during speech production. The measurements included lung volume, rib cage volume, and abdominal volume at utterance initiation and termination, volume excursions during the utterance, and the number of breath groups during the speech task. There were no significant differences between the mask-on and mask-off conditions in volumetric and frequency measures. A significant task difference for abdominal initiation was found. It was concluded that the use of a circumferentially vented pneumotachograph mask does not alter the reliability of respiratory volume and frequency measures for studies of voice.