Final answer:
The fluid found between the bony and membranous labyrinths of the inner ear is known as perilymph.
Step-by-step explanation:
The fluid found between the walls of the bony and membranous labyrinth is called perilymph. This fluid occupies the space within the labyrinth bony, a hollow structure that is part of the inner ear, which contains the sites for transduction of auditory and vestibular information. The vibrations from the middle ear ossicles are transmitted through the oval window into the perilymph of the scala vestibuli, initiating a wave-like motion of fluid within the cochlea. This movement of fluid causes the sensory cells within the cochlea to send signals to the brain, allowing us to process sounds.