Handheld laser-fiber vibrometry probe for assessing auditory ossicles displacement

Significance: Measurements of auditory ossicles displacement are commonly carried out by means of laser-Doppler vibrometry (LDV), which is considered to be a gold standard. The limitation of the LDV method, especially for in vivo measurements, is the necessity to expose an object in a straight line to a laser beam operating from a distance. An alternative to this approach is the use of a handheld laser-fiber vibrometry probe (HLFVP) with a curved tip. Aim: We evaluate the feasibility of an HLFVP with a curved tip for measuring sound-induced displacement of the auditory ossicles. Approach: A handheld vibrometer probe guiding the laser beam with a fiber-optic cable was used for displacement measurements of the incus body and the posterior crus of the stapes. Tonal stimuli at frequencies of 0.5, 1, 2, and 4 kHz were presented by means of an insert earphone positioned in the outer ear canal. The probe was fixed at the measurement site using a tripod or hand-held by one of the two surgeons. Results: The measurements were carried out on six fresh temporal bones. Multivariate analysis of variance showed statistically significant differences for stimulus frequency ([Formula: see text] , [Formula: see text] , and [Formula: see text]), bone ([Formula: see text] , [Formula: see text] , and [Formula: see text]), and measurement site ([Formula: see text] , [Formula: see text] , and [Formula: see text]) in the absence of statistically significant differences for the probe fixation method ([Formula: see text] , [Formula: see text] , and [Formula: see text]). Standard deviations of the means were 6.9, 2.6, 1.9, and [Formula: see text] for frequency, bone, site, and fixation, respectively. Ear transfer functions were found to be consistent with literature data. Conclusions: The feasibility of applying HLFVP to measure the displacement of auditory ossicles has been confirmed. HLFVP offers the possibility of carrying out measurements at various angles; however, this needs to be standardized taking into account anatomical limitations and surgical convenience.