The information about vibrato and tremolo is mostly correct that we
have read here-- only, no one has addressed the fact that there may
actually be two or more sets of terms.

Physical science defines and separates tremolo and vibrato, but that
doesn't mean they occur separately. They always occur simultaneously in
acoustic instruments. But that doesn't stop us musicians from claiming
special inspiration when we have one way or the other to undulate a
tone. Whether an air column of a vibrating string, if you change its
frequency, you also change its amplitude, and vice versa. Granted, one
will often take precedence. You can have a larger degree of AM than FM,
and vice versa, depending on how you do it. (That is, amplitude
modulation and frequency modulation).

Art Reblitz was speaking of a very legitimate term called "orchestral
tremolo." There is no such thing as "orchestral tremolo" on a piano
score, for instance. So while the violins are vibrating (shaking) their
bows on a string and creating a "tremolo" effect all together, the
piano is definitely not "machine-gunning" a note to do the same. Why
not? Because this method of creating tremolo is an effect that only a
bow can do directly on a string when allowed to keep the string singing
with short, fast strokes. If the tremolo is realistic then, the tone
will not die away, and between a dozen or so violins, it  gives the
effect of a tremolo to the orchestra. But that's a musical effect-- not
a true (scientific) tremolo. Still-- they had to name it something. The
piano pounding away on the other hand, proves one thing-- the effect
isn't at all the same!

Tremolo, analytically, is NOT the interruption of a note. That could be
called PM-- pulse modulation, perhaps. And still, that same effect is
used at times on the piano too, and musicians do call it tremolo.
Tremolo is the undulation of amplitude-- speaking strictly to physical
principles.

When we are speaking about tremolo versus vibrato, we confuse ourselves
with cross-terminology. We need to clarify to others that we are
referring either to the musical genre, or the mechanical music effect,
or the scientific term, or the slang term (at which time, we could
clarify what we mean by it, and-- at the same time-- respect the other
guy's terminology.) And then, once we've done that, we have no right
to define our musical term with precise scientific definitions. That
is what usually happens in this discussion. We equate a music term to
a scientific term and try to prove what we believe by pointing to some
sheet music and saying "See there? It says tremolo! That means, you do
not modulate your tone! You undulate the amplitude. And if I hear you
violins doing that again, I shall fire the lot of you!"

You might ask a violinist, "What do mean by tremolo, " and he would
quickly shake his bow on a string, creating an undulating effect. Then
you might ask him, "What do you mean by vibrato," and he would play his
string smoothly, and only his pressure finger would rock back and forth
on the string against the bridge. He would say, "Do you hear the
difference?" And you would say, "absolutely. They are all-together
different."

Now take as an example, an organ with two effects. There is the tremolo
that shakes the reservoir, and there is an electrical cutout that opens
and closes the pipe magnet circuits, allowing them to turn on and off
at a realistic tremolo rate. We will call them both tremolo. Are they?
Or if we call one of them vibrato, is it?

The answer is, yes-- and no. Because making and breaking a pipe air
curtain across the mouth to start and stop a pipe at a tremolo rate
creates both AM and FM effects. Shaking the reservoir so that the
pressure is modulated also creates AM and FM effects. The violinist
undulating the string with his pressure finger creates both by causing
the standing waves on the string to collide and cancel in order to
change the frequency of the string, thus he creates amplitude
modulation as well as frequency modulation. And when the violinist
shakes his bow on a string to create "tremolo," he also is rather
aggressively changing the amplitude with each "see and saw" of the bow
as well. Like the song says, "Ya can't have one without the o--ther."
(Uh-- that is, the musical opinion).

But think of all the ways to create musical vibrato and tremolo! If all
the strings played staccato, it can be done (and is done)in such
fashion as to react on the ear as a type of tremolo! You can strike the
string with the bow and create a type of tremolo by staccato if done
super fast, and you can stroke the string rapidly and create another
type of tremolo. It was pointed out to me that even chopping legato
could be a form of tremolo.  Musically, I agree. Physically, I disagree.

Musicians should acknowledge all the different ways the orchestra has
to create "musical effects" which they call tremolo and vibrato. Are
these pure forms of those effects? Absolutely not. Well then, why call
them that? Because its lingo. Just remember the basics and you won't
have to get too technical about it. There is no way that an acoustic
instrument can have pure (scientific) vibrato without tremolo, and vice
versa.  There is no pure vibrato or pure tremolo-- until you get to
electronic organs and music machines. Even a theoretical pipe chamber
whose shutters are able to open and close at a tremolo rate will still
vary the frequency a little bit by loading the pipes they affect at
their rate of closure (the pipes also affect each other). By placing
the pipes at one end of the room, and operating the shutters a long
distance away, you are able to create pure tremolo I suppose (loading
negligible), but now you are purposely isolating the effects for
scientific purposes of measurement and study! You no longer have a
voiced and balanced organ, per se. You have a lab setup.

So it is musically correct but scientifically incorrect to say that
tremolo is the continual interruption of a note, and that by see-sawing
the bow on a violin string, you are creating true pure tremolo as a
physicist would define it. You are not. You are going through the
procedure called for by the score to make a certain sound, and the
score says below it, "tremolo." Pure tremolo must be made without any
frequency change in the note at all, and pure vibrato must be made
without any amplitude modulation. Musicians who really want to know
what they are doing ought at least to understand these basics and
stop worrying about it. Also, there is another effect the ear might
integrate as "tremolo--" created by quickly interrupting a note fast
enough to create an undulating tone, but to a physicist, if the tone
is fixed, that would be classified as PM-- pulse modulation of a sort.
That's strings repeated rapidly to emphasize a countermelody, for
example. It's a cool effect, but it ain't tremolo, technically speaking.

Ultimately though, the ear likes them all. It likes to be fascinated,
and so these different aspects of tremolo and vibrato add very pleasant
coloration to the music. Like I said previously though, in acoustic
instrumentation, it is not practical to separate pure tremolo from
vibrato. So when we refer to these effects in an analytical manner like
this thread began with, and as I am doing here, I think it behooves us
to define our jargon, so we can appreciate the different viewpoints
between science, and music, and especially all the different musical
simulations which are employed in hundreds of different instruments to
effect it.

I think, that in light of these facts, it really doesn't behoove us
musicians and music lovers to get all that strict and precise with our
terms "vibrato" and tremolo" to teach and define what we perceive as
their differences scientifically, when neither we, nor our instruments
can produce either in any sort of pure form. We merely simulate the
effect to the ear in a multitude of ways, all of which are legitimate,
musically. And if those terms are defined for specific instruments and
are written on the sheet music, use those terms, respectful of the fact
that we are not speaking from the lofty towers of science.

Craig Brougher