In a recent advertisement for high-end cables, one manufacturer wrote:
"Donít take our word for it, let the most sensitive listening devices on earth, your ears, confirm to you that ________ products deliver the truth, the whole truth and nothing but the truth... so help you Stradivari if you settle for the second best! _____ Cables - Love at First Sound."
When this ad was posted on one of the hi-fi group
sites, one audiophile responded with this:
"Donít take our word for it, let the most sensitive listening devices on earth, your ears", not my ears or any human ears are even close to the most sensitive listening devices known to man on this earth. Laboratory test instruments are orders of magnitude more sensitive to frequency, phase, time, decibels in micro-decibel increments, etc. How would listening to a recording with _______ cables allow me to decide what the truth was when I was not present at the original recording to know what the truth was in reality?
I have to agree with the part of his comment
about not being able to know the truth because he wasn't there, but I also have
to point out that even if he had
been there, unless he had been listening from the exact locations of all
of the microphones (a difficult feat at best) he still wouldn't know
what the truth was Ė because he wouldn't have heard it the way they did.
As to the other part of that person's comment,
though Ė the part about "... Laboratory test instruments are orders of
magnitude more sensitive...", I can't agree at all. The fact of it is that,
for three reasons, their own ears
really are very best test instruments that anyone could ever use.
The second reason may seem to cancel-out the first, but, in reality, it's what makes the first one true: Your ears really are Ė not just subjectively, but in measurable fact Ė very much better than even the very best electronic test equipment:
The normal threshold-to-threshold range of human hearing is typically stated as encompassing 100dB, from about 30dB absolute, the "threshold of perception" (where sound first becomes audible to most people) to the "threshold of pain" at about 130dB absolute (equivalent to the sound of a Boeing 747 taking-off just 50 feet away.) Because decibels are a relative measurement, calculated logarithmically; because they represent not any specific sound level, but the ratio of one sound level to another; and because each successive 10 times increase Ė one full order of magnitude -- over the prior sound level results in an increase of just 10dB, thus a 100dB increase over an original reference level (in this case, 30dB absolute, also called 30dBSPL) indicates an increase in sound pressure of 10,000,000,000 to 1 (ten billion to one) over the reference level!
Put differently, the "threshold of perception"
(30dBSPL) reference level is only 0.0000000001 as loud as the 1.0 level
(130dBSPL) at the threshold of pain. How many test devices have you ever seen
that could read that? How many Ė in any field of science or technology, for
any purpose whatsoever -- have single-scale resolution to ten significant
digits? None? Well, your ears do!
Picking-up on that word "significant", hereís where it gets interesting: Suppose we were still back in the days when we were concerned with product specs and we saw that (for example) an amplifier had just one one-thousandth of one percent fourth harmonic distortion (0.001%). Would we be impressed? Would we want to rush right out and buy it?
To figure that out, letís start with two single
tones Ė sine waves of 200 and 1600 Hz, both of which are well within the
frequency range of human hearing (or even of the average old-time telephone).
Now, letís play those frequencies through our amplifier, with the 200Hz tone
at a robust 100dBSPL and the 1600Hz tone quieter, at 50dBSPL. Because both
levels are comfortably within the range of normal human hearing and because the
tones are significantly different in frequency, even though one is 50dB louder
than the other there should be no "masking" effect and we should easily be able
to hear two separate and distinct tones.
Now letís take those same two tones, played at
the same relative volume levels through that same amplifier, and run the ampís
output into a Distortion Analyzer. What will it show? Well, remember that the
200Hz tone is 50dB -- 100,000 times -- louder than the other. Or, to turn it
around, the 1600Hz tone is 100,000 times quieter
than the other, being just 0.00001 times (0.001%) as loud as the 200Hz tone.
Whichever way you describe it, because the tones are exactly three octaves apart
and because of the way test instruments work, the Distortion Analyzer wonít
"see" the amplifierís output as separate tones at all, but will indicate a
200Hz tone with one one-thousandth of one percent fourth harmonic (1600Hz)
Is that 0.001% distortion "significant"? It
better be! If we were to rely on the test instrument reading instead
of our ears, and insist that 0.001% distortion canít possibly be significant,
we might find ourselves listening to just one tone and losing the other one,
The fact is that the only thing that instruments do better than ears is quantification. Unlike test instruments, our ears don't have a meter-needle or a digital display to indicate exactly what it is that we're hearing ("...in micro-decibel increments...", as that audiophile commenter wrote), but we do hear it, nonetheless, and that, finally brings us to the third reason -- the non-numerical one -- why our own ears are the very best test instruments we can use:
When we listen to anything at all, whether words, music, or just ambient sounds and noise, we're not measuring. Instead, we're seeking something entirely different. From words, we're trying to garner information or meaning ; from music, what we want is an emotional response or the kind of kinesthetic magic of tone and rhythm that sets our spirit soaring and our body dancing.; and from background sound we want warning of impending danger, notice of what is around us, or just the soundtrack for our lives. In every case, though, the input from our ears is run through our brain and filtered or highlighted to conform to our own interests, priorities, emotions and hierarchies of value. That's what ears are for, and nothing does it better.
So forget measuring; leave that to the
manufacturers and engineers who are trying to build things to please you.
Instead, why not just relax, put on your favorite disc, and...
Enjoy the music.