Summary of: Voss, S. E., Horton, N. J., Woodbury, R. R., & Sheffield, K. N. (2008). Sources of variability in reflectance measurements on normal cadaver ears. Ear and hearing, 29(4), 651–665. https://doi.org/10.1097/AUD.0b013e318174f07c
This study looked at how absorbance measurements can be affected by the following variables: 1) measurement location in ear canal, 2) cross sectional area of the ear canal, and 3) the middle ear cavity volume. Nine human cadaver ears were chosen for the experiment which did not have any history of middle ear pathology. The results showed that variations within an individual ear with respect to either measurement location or ear-canal cross-sectional area resulted in relatively small effects on absorbance. However, increasing the middle ear cavity volume was found to increase absorbance below 2000 Hz. Frequencies above 2000 Hz showed more variable results when middle ear cavity volume was increased. The authors conclude that middle ear cavity volume is likely to be the cause of inter-subject variations in absorbance measurements.