[Harp-L] Differences between ears

["fsiyfr" <fsiyfr@xxxxxxxxxxxxx>]

I have a couple examples of differences in hearing that relate to the
ability to detect low levels of harmonics/overtones or really high
frequencies.

Back in the early sixties, a lab instructor showed his ability to hear the
added frequencies when distortion occurred in an audio amplifier that was
overdriven slightly.  We (the students) had various instrumentation hooked
up to the output of an audio amplifier (including an oscilloscope, which
gave a very visual display of distortion).  We'd run the audio drive to the
amplifier up and down, observing the point at which distortion could be
detected by the instrumentation.  Our instructor could (out of view of the
instrumentation) tell us exactly at which level the distortion started to be
barely noticeable, just using his ears.  He could hear those additional
tones that creep in when distortion occurs, even at a very low level.  None
of us students could hear it (until the distortion got quite prominent). The
instrumentation verified that his observations regarding the starting point
of distortion were accurate. This guy could probably detect nuances of
difference between harmonicas of various constructions.  Because he could do
this stunt every time.  It really impressed us.  Distortion had to reach a
much higher level before any of us could pick up on it with our ears.

A few years ago, a sound system consultant came to our church to fine tune
the equipment there.  A number of those with interest in the sound system
were there to get some instruction from the consultant.  In the course of
his presentation, he put some high frequency audio tones through the system.
The younger guys were writhing in agony--their ears still had good high
frequency response.  Older guys (me included) didn't hear those high tones
at all.  It was as if they didn't exist.  This made me realize that younger
men and most women probably hear a somewhat different sound than I do, when
I'm playing the harmonica.

Dan

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Message: 5
Date: Sun, 30 Dec 2012 20:12:27 -0800 (PST)
From: David Payne <dave@xxxxxxxxxxxxxxxxxxxxxx>
Subject: [Harp-L] Differences between ears
To: Harp L Harp L <harp-l@xxxxxxxxxx>
Message-ID:
	<1356927147.47608.YahooMailNeo@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
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There is a book about the Battle of Outpost Harry in the Korean War by James
Evans, who was commander of Company A, 5th Regimental Combat Team, a company
of about 180 men who successfully defended the outpost from an attack of
15,000 Chinese in June 1953. My grandfather was the company's radio
operator. 
My grandfather was an incredible musician and he had a remarkable ear.
Better than mine. 
The scene I'm about to describe was from the night of June 11 - 12, 1953.
Evans, my grandfather and a jeep driver were traveling to relieve the
company defending the outpost. They were, at this point, separated from the
rest of the soldiers in the trucks behind them. Technically, the book does
not say which of the two this soldier was, but I know how good my
grandfather's ear was and thus presume it was him and will explain this as
if it were him. 
As they were traveling this Korean backroad between the American and Chinese
lines (the outpost itself was between the lines), these Chinese shells start
pouring in. They jump out of the jeep and dive into a ditch. 
Evans explains:
"One soldier in our group had remarkably good ears. Even kneeling in the
ditch, he could hear the incoming. Before I could hear anything, he would
cry out "Here comes another one!" About a second later, my own ears could
pick up the roar. Then, we were shaking and ducking again." 

The muzzle velocity of Chinese 122mm howitzer is around 1,800 feet per
second - that's faster than sound, so the shell gets to you before the sound
of the gun firing. Let's say that by the time the shell got near them, it
had slowed down to 1,300 feet per second. About the fastest I can say "here
comes another one" is about a second or so. That's two seconds, minimum and
not counting reaction time, etc.
Hearing it just two seconds early means that shell traveled for at least
half a mile and my grandfather could hear that shell move while everyone
else heard nothing.
My vision isn't that great, I'm farsighted. I've been wearing bifocals since
I was 20 years old, but I also shot a deer once at 300 yards with no scope,
just the stock iron sight on an Enfield rifle. I can see really well far
off, but I can't see a dang thing up close without my bifocals - I can
barely read my watch without them. 

I can't imagine hearing being much different than vision in that regard. I
would imagine that just as we all see differently, we hear differently, too.


If I can make it SPAH next year, I would certainly be happy to guinea pig
myself on this stuff. I would really like to do a brass comb vs plastic or
something test.

David Payne
www.elkriverharmonicas.com
www.hetrickharmonica.com