GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Playback Listening
In the Thread: The Sound and How We Hear It

Post Subject: The Sound and How We Hear ItPosted by drdna on: 11/8/2008

How do we hear?

A recent article examined the capacity of the optic nerve to process visual signals. Based on the number of neurons in the retina, etc., an estimate of less than a megabyte of information was found, which is surprisingly low. This would produce a grainy image, at best. However, this is not our experience of vision. We see the world as a seamless, continuous ultra high resolution three dimensional experience, to which all our hi definition photographs pale by comparison. Considering further that all the information we receive through our eyes passes through a thick vitreous jelly before getting to the retina, it is a puzzle.

The answer to this is the incredible processing power of the brain to take this raw data and create the illusion of a seamless crystal clear image. The same is true of hearing. In fact the impulses received by the cochlear nerves are heavily processed in a complex bilaterally interactive redundant network of neurons in the brain. Thus much of how we hear is the product of our brains.

Since we are all different, we all hear differently. This may explain much of the controversy that occurs in the audiophile world. Why do stereos sound different? Why do loudspeakers that are much beloved and praised by some folks sound horrible to others? Is it a case of "wooden ears" and equipment reviewers accepting payola for good reviews? Perhaps not.

In fact, we may all be trying to achieve the same ideal result with stereo, but because we hear differently, we may require different input to achieve this ideal in our brains.

An interesting analogy is the well-described phenomenon of the "super taster." The number of taste buds on our tongues varies actually quite a bit. People with a lot of taste buds can discern extremely subtle flavors and are highly prized in industries where evaluation of complex taste is at a premium, such as the wine industry. However, these "super tasters" tend to prefer very bland mildly sweet foods, while people with fewer taste buds prefer strong flavored spicy foods. Why? Again, we are all probably seeking the same ideal flavor balance. We spice foods to compensate for the sensitivity of our tongues.

Likewise, we build stereos to accommodate for the variations in how we hear. One aspect of this is the concept of additive and subtractive error. Let's think of it this way: A ice cream cone manufacturer makes a vanilla ice cream cone dipped in a hard chocolate shell. He takes a photo of it and sends it to his employees so they can use their ice cream makers to make the same cone for customers. In this analogy, the ice cream cone manufacturer is the musician, the photograph is the vinyl record or CD, and the employees' ice cream machines are stereos.

Some employees have machine that have sprinkles mixed in to chocolate, so the cone they make has all the original ingredients plus the extra sprinkles. This is called additive error. Other employees have machines that make the chocolate coat far too thick, so they scrape it off to match the photo, but some of the original ice cream comes off too. This is called subtractive error.

In audio, some listeners will likewise prefer a system with subtractive error, where some of the original information is lost, but any added distortions are minimized. These are the audiophiles who prefer analytic "inner detail," paring away more and more of the music to "reveal" the details.

Other listeners prefer a system with additive error, where the original information is retained, but some distortion gets added as a trade off. These are audiophiles who prefer a colorful "musical" system.

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