The linearity of the output signal of a laser Doppler flowmeter through the cochlear bone was investigated by model study. The model consisted of a highly diffused plate, a bundle of hollow fibers, a lateral bony wall of the cochlea of the guinea pig. The lateral bony wall was placed on the bundle of hollow fibers. The diluted heparinized blood was infused into the bundle of hollow fibers at predetermined flow rates. The flow was measured through the bony wall with the laser Doppler flowmeter (PF2, Perimed, Sweden). The results showed the output signal was proportional to the product of the blood velocity and hematocrit (r=0.97). However, the magnitude of output signal was obviously attenuated comparing with the direct measurement.
