My next few weekly blogs will concentrate on what speaker
specs really mean to us guitar players in the “real world”. I wanted to jump right in to a
discussion of efficiency, frequency range, and so on – but I realized that I
was getting a little ahead of myself.
When I teach introductory audio engineering classes, I always
start with a day or so on what sound actually is and how the human ear “hears”
it. Since this is so basic to
anything and everything audio, I decided it was prudent here as well. I’d like to point out that the human
ear is in fact an electro/acoustic transducer, just like a microphone or
speaker is; I’ll get to that in a moment.
Let’s start with what “sound” is.
Sound in a given space is actually air molecules in motion –
it’s a very “physical” thing.
Think of one molecule crashing into the one next to it, now imagine that
happening many thousands of times and you have an idea of what sound is. Let’s say you hit a snare drum or a
chord on an acoustic guitar, what you have just done is sent a bunch of air
molecules flying! They bash into
the ones next to them that then bash into the next ones and so on and so forth
– just like in a multi-car pile up on the freeway. As this goes on, each subsequent “collision” looses a bit of
its energy (it’s actually dissipated as heat) until there isn’t enough energy
left to put any molecules in motion.
In other words, it gets quieter as it moves away from the sound source. This is an oversimplification to be
sure – but what I want you to remember is what sound really is – air molecules
that have been set in motion and subsequently set other molecules in
motion. This is important because
that is precisely what a loudspeaker needs to accomplish to produce sound. Just as one guitar may be able to do a
much more accurate and articulate job of moving air molecules than another
(leading to better sound), so can the same be said for one speaker over
Now on to the electro/acoustic transducer that our creator
saw fit to endow each of us with two of – the ear. Just like a microphone, the ear takes the acoustic energy
(sound) I just described and converts it into electricity. That electric signal is what our brain
understands as “sound”. However,
and this is what I want you to remember, the human ear is insanely sensitive –
and like all sensitive instruments can be easily damaged. In essence, the outer (visible) portion
of the ear collects the moving air molecules and focuses them on our outer ear
drum. The outer drum is connected
to an inner drum via three nearly microscopic bones (they’re shaped like a
hammer, an anvil, and a stirrup).
These little bones serve to amplify the movements of the outer drum, so
the inner drum’s response is exaggerated.
Then, sealed in the inner ear behind that second ear drum is the auditory
nerve which is lined with thousands of microscopic hairs (called cilia) that
actually flap in the “wind” and thereby create the electrical signals sent to
the brain. The hairs that hear the
lowest frequencies are comparatively robust and toward the back of the
inner-ear while the hairs that detect high frequencies are extremely fine and
are right up next to the inner ear drum.
That’s why people generally loose the high frequency portion of their
hearing first. Those little hairs
are very easily damaged or destroyed!
What does this mean to you? First, be VERY careful with your ears, you just might want
to use them when your old. Second,
be aware of the fact that everybody (especially men) experiences some amount of
high-frequency hearing loss as they age. If you’re a man over 50 or so, it’s
probably already started for you.
So, if that 20-something sound man tells you your guitar tone sounds
shrill and thin, he’s probably right.