Voice sound pressure and esophageal pressure amplitudes are measured for 120 subjects with and without laryngeal status. The esophageal pressure amplitudes are taken as a approximation of the subglottal pressure. The dependency of sound pressure on subglottal pressure is approximated by a nonlinear function. The slope of the function represents the pressure transformation from subglottal pressure to sound pressure at fixed vocal tract configuration. Therefore, the slope is taken as a characterization of the efficiency of the voice organ. This quantity allows rough statement about the efficiency of the voice organ (differentiation of normal, trained normal, and pathologic larynx) but does not separates voice disorders.