Estimation of stapes piston motion with uni-directional measurements is prone to error
Faculty of Sciences. Physics
Singapore :World Scientific, 2007
Middle ear mechanics in research and otology / Eiber, A. [edit.]
University of Antwerp
In most experiments, access for direct measurement of stapes motion in line with the piston axis is not available and piston motion is estimated from single component interferometric measurements done under observation directions that make angles up to 60 degrees with the piston axis. We measured the vibration velocity of the stapes in human and gerbil from different observation angles and calculated the complete set of 3-D motion components. We expressed the components in an intrinsic reference system and could foretell the motion component to be recorded with a single axis interferometer at an angle with the piston axis. A cosine factor provides a good correction for the axis offset only for low frequencies (f<1.5kHz) in human; at higher frequencies and for gerbil at all frequencies the piston component cannot be accurately estimated from a single off-axis observation and a cosine correction.