Aerodynamic profiles of a hemilarynx with a vocal tract

The pressure-flow relationship was examined in excised canine and human lar ynges with and without a vocal tract. Canine and human larynges were prepar ed and cut in the midsagittal plane from the top to about 10 mm below the v ocal folds. Tile right half was removed and replaced with an acrylic plate. The vocal tract was simulated initially with a 15-cm plastic tube and late r with a vocal tract model with an area function resembling "ah." Simultane ous recordings were made of the glottal pressure, mean subglottal pressure, and average airflow at various levels of adduction. preliminary data indic ated that the pressure-now relationships were similar to those of a full la rynx and were almost linear. The addition of the vocal tract increased the glottal resistance by moving these pressure-flow lines to the lower-flow an d higher-pressure region. The human larynx appears to phonate more easily t han the canine larynx on the laboratory bench and has lower phonation thres hold pressures.