Baleen whales react to noises such as boat engines and cameras clicking underwater. Baleen whales have a small external ear opening on each side of the head. Each opening leads to a narrow auditory canal that is completely closed by a waxy substance and reduced to a strand of fibrous connective tissue. 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.