Handheld laser-fiber vibrometry probe for assessing auditory ossicles displacement

Abstract

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 (F 3;143 ¼ 29.37, p < 0.001, and η 2 ¼ 0.35), bone (F 5;143 ¼ 4.61, p ¼ 0.001, and η 2 ¼ 0.01), and measurement site (F 1;143 ¼ 4.74, p ¼ 0.03, and η 2 ¼ 0.02) in the absence of statistically significant differences for the probe fixation method (F 2;143 ¼ 0.15, p ¼ 0.862, and η 2 ¼ 0.001). Standard deviations of the means were 6.9, 2.6, 1.9, and 0.6 nm∕Pa 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.

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“…The measurements are point measurements. To evaluate areas, multiple measurements at the selected location must be conducted ( Drain, 1980 ; Nuttall et al, 1991 ; Stasche et al, 1993 ; Ulfendahl et al, 1996 ; Maier et al, 2013 ; Masalski et al, 2021 ).…”

Low‐Field Actuating Magnetic Elastomer Membranes Characterized using Fibre‐Optic Interferometry

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