ASA 124th Meeting New Orleans 1992 October

2pSP3. Timing and magnitudes of oral and nasal flow in cochlear implant patients and normals.

Res. Lab. of Electron., Rm. 36-511, MIT, Cambridge, MA 02139

Vowel nasalization was assessed in cochlear implant patients pre- and post-implant, and in normal-hearing speakers, using measures of oral, nasal, and total airflow. Speech materials consisted of the utterance /taC/, (where C=/n/, /m/, or /d/, embedded in a carrier phrase. Airflow was transduced with a two-chamber Rothenberg mask. Measures included the relative timing of the onsets of nasal and oral airflow, and the ratios of peak oral and nasal flow to total flow following the /t/ release. Pre- to post-implant differences may reflect an adjustment of the control of the velum, possibly in response to a perceived difference in nasalization and/or as a consequence of concomitant changes in other speech parameters. Preliminary ratio data from one cochlear implant patient indicate a possible enhancement of the nasal/non-nasal contrast post-implant. Further, in the /tad/ utterance, the oral flow pulse at consonant release was accompanied by a small pulse of nasal flow: velar closure during the consonant may have been assisted by the oral pressure increase, thus the pressure drop at consonant release would result in a small passive velar opening movement. These observations and additional measures are being explored further. [Work supported by NIH.]