The auditory system is essential for normal functioning communication including species specific vocalizations that convey information about territory, reproduction, warning, etc. Human communication in the form of speech is the basis for the unique place of humans in the evolutionary chain. We hear and visualize things and events that important to us, not the actual sound waves or light waves. Understanding the function of these structures is limited by our ability to manipulate them in meaningful ways, especially in humans where we have to wait for appropriate lesions in the brain and note the resulting deficits. In contrast, the use of invasive studies in animal-based research has led to a vast knowledge base over the years that encompasses anatomical, physiological, molecular and genetic data often obtained in the same set of experiments.
Modern techniques permit correlation of structure and function in the brain.
There are many newer methodologies that permit gathering information in humans. A tiny bit of History. They may have discovered the theoretical basis for music. It is of course possible that similar levels of comprehension of sound and hearing were present in other cultures, e.g., in China though the documentation isn t available. Aristotle generalized the notion of Phythagorus and realized that the propagation of sound involved the variation in density of the medium.