FIG. 10.
Initial forward pressure (Pifw) at constant voltage is similar to the pressure response measured in the LLT, where reflected waves are negligible. The ∼10 dB spread in level between different ears shown in (a) is reduced considerably when the pressure is normalized by the ratio of the actual cross-sectional area of the LLT to the area of each ear canal, calculated from the estimated surge impedance (b). This result indicates that the variation in estimated surge impedance in each ear is, in fact, caused by variations in the cross-sectional area of each ear canal at the point of measurement.