Audiovisual Perception

1 Hearing versus Seeing

Our faculty of perception is a response to the surplus of information in our environment. According to Konrad Lorenz, every sense organ embodies a theory as to which information about the environment promises an evolutionary advantage.[1] Every sense focuses on a small selection from this nearly infinite variety and thereby opens a gate to another world, so to speak. The perceptual worlds that seeing and hearing open up for us are characterized, to put it simply, by the mode-specific features described here.

By perceiving high-frequency light rays with wavelengths from 380 to 680 nm that move in nearly straight lines, the eye can resolve surface structures with extremely precise detail. This gives us the capacity for extremely precise spatial orientation, as is evident, for example, when we read tiny structures such as writing. The human auditory system, by contrast, is optimized to understand the human voice. The sound waves in this range, with wavelengths from about 20 to 30 cm, bend around smaller objects and hence are comparatively poorly suited for the precise perception of space.

Seeing is a targeted and directed process that takes place actively and consciously. As a rule, sensory stimuli are transferred directly to the cerebrum for rational processing, which makes visual perception ideally suited for dealing with highly differentiated inputs. Several nerve tracts lead directly from the ear to the diencephalon, or interbrain, which is responsible, among other things, for controlling the emotions. That is why acoustic stimuli are able to trigger relatively direct feelings and physical reactions (such as an increased pulse rate). Moreover, the ear is immobile and cannot be closed, which is why, like it or not, we register all acoustical events in our surroundings, even when we are sleeping. Hearing often occurs unconsciously and passively and can be described as totalizing and collectivizing, since acoustic perception will largely coincide for several people in a room.

Our visual perception is optimized for grasping static objects and can, as a rule, follow no more than one movement, such as a passing car. Acoustic phenomena, by contrast, are practically inconceivable without dynamic changes. When we listen, we have no problem distinguishing between several simultaneous movements, such as the noises of two different cars driving away. Moreover, the sense of hearing is fundamentally faster than the sense of vision in taking in and processing sensory stimuli. The ear thus tends to specialize in the perception of temporal processes and the eye in the detailed resolution of static phenomena, which is probably the basis of the common association of images with permanence and sounds with ephemerality.[2]