Once in a while piece of new research will remind you that some things that seem a given are just not. Take for example this paper on a species of earless frogs listen with their mouths. As incredible as that may sound these frogs do indeed react to mating calls. In other words you don’t need ears to be able to take advantage of physical properties of sound.
We all know bats use sonar to hunt for prey in the dark and that dogs can hear high pitch sounds we can’t (think dog whistle). Even children can hear sounds that adults no longer can. As a parent I sat through a science show for kids once where they played sounds which my kids nonchalantly reacted to but I couldn’t hear at all. I literally heard nothing. It just goes to show much we rely on the “equipment” for the interpretation of the world around us.
The top award though must go to the mantis shrimp though. This animal can see 100,000 shades of colour, ten times more than humans. There obviously must be a need for it to be able to do so otherwise it would have become redundant and have been whittled out of the species through natural selection.
But opposite must be true too of the limited range of human-made sounds. A while back I wrote about the Japanese’s inability to distinguish between the ‘l’ and ‘r’ sound. In Japanese this distinction doesn’t exist. It isn’t necessary for their language and communication so they therefore need not either to bother hearing it or producing it. The moral of the story is the sounds within Japanese language more than adequately suffice for their need to communicate what they want to say.
There are two lessons here: one is that what counts as sensory perception and faculty is not so clearcut. And second, you don’t necessarily need to hear everthing, that is, our minds filters out things, to separate “the noise from the music” so to speak. And this has consequences for the development and acquisition of language which essentially is a manipulated layer over sound and sight.