The effectiveness of sound reception and hearing through the ear canal is unknown. The middle and inner ear follow the basic mammalian ear structure. More research is needed to determine the exact mechanism for sound reception in baleen whales. A foam surrounds the ear bones. This foam contains air.
Air stops sound waves traveling through water and living tissues.
Many scientists believe that this foam acoustically isolates the ears, enabling a whale to tell from which direction a sound comes. Because the ocean is often dim, baleen whales have adaptations for vision in low-light conditions. The baleen whale eye is flattened from front to back, and the cornea is less curved. This lowers the refractive index and allows better vision in low-light conditions. A tapetum lucidum, a reflective layer behind the retina, reflects light back to the retina a second time.