* preliminary draft *
It is fairly evident that sensory processing of incoming information essentially is hierarchical, i.e., consisting of a chain of abstracting steps by which the multitude of primary sensory cues is organized into a subjective representation of external objects. It appears that hierarchical processing principally operates on metathetic sensory attributes - as opposed to the prothetic ones. (Metathetic attributes are related to "what, and where"; prothetic attributes to "how much".) Primary methatetic attributes are the contours in vision and the spectral pitches in audition. Understanding the perception of pitch and several related auditory phenomena essentially was enabled by, and is crucially dependent on, the hierarchical approach [10], [18], [20], [22], [53], [65], [66], [72], [75], [76], [87], [88], [93], [94], [96], [99], [101], [104].