Dualview System

The Dualview system will display two airflow channels, nominally the oral and nasal airflow waveforms from a dual-chamber Glottal Enterprises CV mask, and compute and display the %DC Nasalance from these variables.  %DC Nasalance, sometimes referred to herein as just %Nasalance for brevity, is computed from the low-pass filtered oral (Channel A) and nasal (Channel B) airflows, Odc and Ndc, and is defined as 100 Ndc / (Odc +Ndc).  Also displayed is a version of Channel A that is low-pass filtered at a selectable frequency of 400, 500, or 600 Hz to show a roughly inverse filtered representation of the glottal airflow waveform for open vowels. (Channel A, or the sum of A and B, can also be more precisely inverse filtered using the Waveview program or other equivalent programs.)  The nasalance display is comparable to the displays of (AC) %Nasalance obtained from audio waveforms by the Glottal Enterprises Nasality Visualization System and other systems for measuring Nasalance, but the scales will not be directly proportional.

Dualview display for “mamama bababa” spoken by an adult male English speaker. The red lines in the oral airflow (Ch A) and nasal airflow (Ch B) charts show the variation of average airflow that is used in the nasalance computation.