Due To Nagal's 1973 Paper
A sound as a qualia within "consciousness" is computed as sensory information is processed. The bat with sonar probably experiences images comparable to graphics, as humans do. Or they may focus more on functional navigation. Nagal missed that the physical states of systems, specified by state variables, are associated with the behavior of systems due to natural law. The same can't be said of a states producing subjective qualia. A pink spot is experienced as qualia. A "hard problem" is determining how qualia relate to a brain's physical states. The approach to solving it is to understand the brain, with a (billion) ^ (trillion) number of common states. Nagal points out that if qualia are subjective and computed from informational inputs, the qualia as information could not lead to an objective understanding of the outside material system, the source. A qualia sound won't help develop a reductive understanding of the external system. Each organism has only a personally produced "sound" qualia. Nagal concludes that considering all subjectively produced subjective views of physical systems would make objective understanding less likely.