To begin, prepare a laser-induced shockwave, or LISW exposure assembly. Irradiate the exposure assembly with a 532 nanometer Q-switched NDYAG laser to generate the LISW behind the target. Focus the laser pulse through a plano-convex lens to a three millimeter diameter spot on the laser target.
Use the LISW irradiation to generate plasma at the bonding surface of the two materials, and vaporize the rubber, leaving vaporized rubber in the cavity. Carefully shave the postauricular regions of the anesthetized mouse to avoid retaining the trapped air in the fur. Fix the mouse on a plate with their postauricular regions positioned upwards towards the LISW focal area.
To ensure acoustic impedance matching, use an ultrasound conductive gel between the laser target and the skin surface. Attach a black rubber target percutaneously to the postauricular region of the mouse ear. Apply a single LISW pulse to the cochlea via the temporal bone at three energy densities.
Insert a ground electrode under the caudal region of the tail. Then, insert a stainless steel needle electrode for electroencephalogram recording under the ear canal and frontal region of the ear. Present the stimulation sound over a small earphone and measure the sound pressure level near the tympanic membrane of the mouse.
Generate output burst stimuli from a sound generator at 37 cycles, and amplify the sound pressure from a 20 decibel sound pressure level to 80 decibel SPL in five decibel SPL steps. Measure the auditory brainstem response, or ABR peak one amplitude, to evaluate the cochlear functions. Then, ABR peak analysis software automatically analyzes the ABR waveforms with respect to the hearing thresholds and ABR P1 amplitude.
An auditory function assessment using ABR post LISW exposure revealed significant ABR threshold shifts at one day, persisting for one month at higher energy levels. ABR thresholds in the two joules per square centimeters group showed recovery to pre-exposure levels, indicating energy dependent effects. After one day and one month of LISW exposure, significant decreases in ABR P1 amplitudes were observed in all LISW irradiated groups across frequencies.
