Weismer G, Longstreth D
J Speech Hear Res. 1980 Jun;23(2):383-92. doi: 10.1044/jshr.2302.383.
Peak intraoral air pressure and flow were measured simultaneously for the syllables /pa/ and /ba/ in two speaking conditions (syllable repetitions, and in carrier phrases) and in two phonation modes (normal phonation and whisper). Results indicated that 1) the difference between the intraoral air pressure for /p/ and /b/ was statistically significant in normal phonation, but not in whisper, 2) the difference in peak flow for /p/ and /b/ was statistically significant in both normal phonation and whisper, and 3) the pressure and flow data were unaffected by speaking conditions. These data, plus a subsequent analysis of intraoral pressure slopes, are taken to indicate that the voiceless and voiced members of a stop-cognate pair are produced in whisper with unique laryngeal gestures.