K7LXC wrote:
> In a message dated 98-04-29 21:46:46 EDT, you write:
>
> << As to 2 db, I was taught in the old days that a 3db *difference* was the
> smallest difference discernible by the human ear. That came from some
> ne'er-do-well outfit called Bell Labs. >>
>
> Actually that's the definition of 1 dB - the smallest difference
> discernible by the human ear.
>
> Cheers, Steve K7LXC
>
Steve,
I think that you are incorrect in saying that 1 dB is the smallest difference
discernible by the human ear. The "just noticeable difference," or "jnd"
defines the smallest difference discernible. The dB is an engineering unit
that is the log of the ratio of two intensities. I think that 3 dB turns out
to be close to the jnd, but even this number varies throughout the range of
loudness. The jnd is not an exact number, varying with people, situation,
time, and a million other variables.
The jnd concept was first propounded by Fechner, around 1860, whose original
attempt to relate human perception directly to physics has not withstood the
test of time, but who propounded some very useful ideas. Some theories of
perception, such as signal detection theory, dispense with the concept of the
jnd.
Jan, KX2A
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