Optical Coherence Tomography (OCT) was used to measure vibrations of the basilar membrane (BM) and the Reticular Lamina (RL) in the cochlea of the guinea pig, at frequencies up to 25 kHz. Because of the difficulty of the experiments the data have limited sets of parameters and are subject to high noise levels. In a viable guinea-pig cochlea, the RL moves in the region of maximum response with a larger amplitude than the BM. We cannot rule out that some of that difference is due to a geometrical factor. We also found a consistent increase of this amplitude difference with frequency, which points to a low-pass filtering process. That process might be linked to the mass of the fluid contained in the Organ of Corti channel (OoC channel).
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