One spec pertaining to headphones, and one not realized in terms of the
importance, is sensitivity. The more sensitive the headphones means it
takes less audio power to produce acoustic energy. If a given signal
say a value of -25 dBv is applied, this signal may be heard with some
headphones and may not be heard with others. Now, adding a series
resistor in effect reduces the apparent sensitivity. In fact, it
reduces the available power to the headphones. In the case of the -25
dBv signal, adding a resistor may reduce this value to -35 dBv, or below
the sensitivity threshold of the headphones. All of this has little to
nothing to do with the impedance of the headphones.
In most instances, everyone's hearing decreases with age. Other factors
that affect a diminished hearing is prolong exposure to noise or any
loud sounds. A combination of sound level and time exposed are key
elements to diminished hearing. Repeated exposure over a long period or
repetitive cycles will lead to permanent hearing loss. And in many
cases this loss is so gradual over a period of years it is not realized
or acknowledged to exist.
From my experience, the audiologist, after a hearing test said my
hearing was normal. Now what he didn't say was "my hearing was normal
for a male of my age". My wife complains that I don't listen to
her. At least that's what I think she said.
73
Bob, K4TAX
On 9/30/2015 7:57 AM, Sullivan, Mike C wrote:
Not sure this helps much other than knowing you are not alone.
I have had the same problem and fixed it exactly as John - VK7JB has - SN on my
K3 is in the 800s.
I have checked my S/N ratio and it is at least as good as the spec.
My hearing has been checked here at work and I have been told that I have good
hearing for anyone these days, and really good for an OF.
I would bet having a pair of good ear-plugs in my pocket from the age of 18 or
so had a lot to do with it.
Just tripped 60 yesterday.
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