Final answer:
The fluid found in the scala vestibuli and scala tympani of the cochlea is known as perilymph, which plays a critical role in the auditory process.
Step-by-step explanation:
The fluid in the scala vestibuli and scala tympani is called perilymph. These two scalae are fluid-filled tubes within the cochlea, which are essential for the process of hearing. When sound vibrations are transferred through the oval window to the scala vestibuli, the perilymph is set into motion, creating waves that correspond to the sound frequencies. This movement stimulates sensory cells in the organ of Corti, which then send the auditory signal to the brain for interpretation. The scala tympani ends at the round window, where the membrane will bulge or pucker in response to the movement of the perilymph within.