Why Do We Care For Our Hearing and Sight So Differently?

April 25, 2011

Recently, I had the rare pleasure to hear Dr. Barry Blesser (Blesser Associates bblesser@alum.mit.edu) address the National Hearing Conservation Association conference in Mesa AZ.  Dr. Blesser was discovering for us why people, normally thoughtful, intelligent, and competent, play music on their digital audio systems loud enough to do their hearing damage.  While I was fascinated by his reasoning, I’m going to borrow from his talk to delve into the consideration of hearing and sight as senses. Before I do, you might be asking why – why discuss the issue? Fact is, many people will protect their sight but do not protect their hearing the same way. I’m curious as to why?

To understand value of hearing to us we need  to look at hearing in an evolutionary perspective. What value did hearing have to us, compared to other senses, in “the beginning”.  Dr. Blesser asks it this way.
Let’s start with a speculative question: what is the purpose of hearing from an evolutionary perspective?  Human beings have an auditory system that is an extension of that which is found in many mammalian species.  Allocating scarce neural resources for the auditory cortex did not originate for speech and music, which is a late addition and expansion of an existing system.

Why then did we evolve our auditory cortex. Originally, all of our senses were focused on preservation.  Sight, Sound, Smell, and to some extent Touch evolved in order to find food and avoid danger.  As Dr. Blesser puts it
Two of the most important senses, vision and hearing, are dramatically different in one key aspect: vision is optimally suited for the perception of objects and geometries that are static;  hearing is optimally suited for the perception of dynamic events because they produce sound.

Hearing also gave us a warning system unbounded by line of sight.  It was therefore much better protection from harm than sight because danger could be perceived from any direction, regardless of obstacle between us and the danger.  Once we “heard” the danger we could focus our eyes in its direction in order to determine a specific preservation action.  Sound radiates in all directions, through narrow openings. It is hard to block and segregate into units. Sound goes where it wants to go.  It reveals the interior state of an object, as in a hollow box or a angry dog
Sound events or time ordered and sequenced. One activity follows another. Sound quickly disappears. It flows in time. There is rarely a static sound.  Multiple sound sources overlap without necessarily obscuring each other. You cannot see behind an object but sound is not equivalently blocked.  Sound never respects ownership boundaries.
Because of its primal importance to self preservation, hearing is hard wired into our cerebral cortex.  We have no “ear lids” to close.  We cannot stop listening as simply as we can stop looking. As a result, hearing is a or the primary sense.

Quoting Dr. Blesser
The origin of hearing predates visual culture, and long before there was reading. Sensory Anthropology (Howes, David, ed. 1991 The Varieties of Sensory Experience) makes the point that the senses have a limited biological meaning compared to the way in which people choose to use them. “Use it or loose it”.

We could therefore conclude that there Cultural norms at play as well.  We don’t need perfect hearing to e-mail and text (and occasionally listen to music).  Dr. Blesser has an answer for why people might appear cavalier in their need to protect their hearing which I’ll try to convey in a future blog.  When we remove hearing, even incrementally, we alter the individuals sense of self, their relationship with their environment, and those around them.

This brings me back to the premise of the blog, we not equally protect hearing & sight; why?    In music, the importance of hearing and sight present a bit of a quandary. Take as an example Stevland Hardaway Morris (Stevie Wonder), Andrea Bocelli, Ray Charles and many more blind musicians and compare them to deaf musicians like Beethoven, Paul Stanley of KISS, Pete Townsend, and Johnny Ray – all of whom started as hearing and lost it later in life.  So far we have somewhat explored the problem. I’d be interested in your thoughts as to why you think this duality exists between hearing protection and vision protection. The conundrum continues.  In a future blog, I’ll tell you what Dr. Blesser says might be the cause for this cavalier attitude towards hearing conservation.  Stay tuned.

6 Responses to “Why Do We Care For Our Hearing and Sight So Differently?”

  1. Rob Wane

    We consider sight and hearing as one of the most important senses in our system especially if we want to be productive and carry out task effectively. The preservation of our system depends on how well we take care of it and how willing are to  defend our body from external or internal factors that may contribute for this senses to deteriorate.hearing loss test Boston MA

    • Marcus:

      Hearing is primal to the human. When we launched out of trees and came to earth what kept us safe (and still does) was our hearing. Hearing works over, around and through objects. Sight is, well, line of sight. Hearing warned(s) us of danger sight localizes it. As Dr. Barry Blesser told me, “we have eye lids but no ear lids”. We never evolved the ability to suspend hearing (despite what our partners say).

  2. Michelle Pasinati

    Wow, this is the great idea. I read your article, So i think, We suffer hearing loss. Because, we are do not care our hear. So To understand value of hearing to us we need  to look at hearing in an evolutionary perspective.Thanks for nice posting.
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    • Custom Protect Ear

      Exactly Michelle. We are “hard wired” to hear. We need to think about the person we are trying to protect and what their needs are before we can have a successful hearing conservation program.

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