We use motion or movement to describe
the continuous displacement of an object in space over time.
But we have also a few other words that are related to this.
And the first one is action.
Here, we move from the physical into the cognitive domain,
since actions only exist in our minds.
We can define an action as a motion sequence
with a beginning and an end.
Actions are often also conscious and goal-directed,
although they do not necessarily have to be.
We live our lives through actions.
We open a door.
We lift a glass.
We play a key on the piano.
And all of these actions are movement sequences
with a beginning and an end.
That sounds simple enough, but it's actually quite difficult
to understand precisely what an action is.
For example, consider that I'm performing
what we could call a basic sound-producing action,
like this.
When you watch this, it may appear
like one coherent action.
But if you're trying to measure it,
we run into question about when it actually begins
and when it ends.
Is the beginning here, or here?
Technically, we may say that such a sound-producing action
consists of three different parts.
We have the prefix, the excitation, and the suffix.
So the prefix is the part before I
hit the stick in which I build up the momentum
and speed of the stick.
Then comes the excitation part, which
is when sound is actually produced when
these two elements collide.
So here we have an impulsive action
with a quick and sudden excitation.
Finally, we have the suffix, which I move the stick back
and prepare for a new hit.
Of course, in real life, these are highly connected.
But it may still be useful to think
of these as three separate elements
when we go into an analysis of the sound-producing action.
Also, musicians spend a lot of time
on perfectionising these elements,
and they all play together when it
comes to producing the final sounding result. Things,
of course, become more complicated
when adding several actions together.
For example, if I played two such strokes,
when does one end and the other start?
And if I combine several actions,
it gets even more complicated.
Are we now talking about eight separate actions?
Could they be grouped into two, or could they
be grouped into any other combination?
We here talking about the phenomenon
we call coarticulation, which means that two or more
elements are grouped together-- both in performance,
but also in the way we experience them.
We're identifying that there are several individual strokes
with a distinct quality, but we also
identify that these are being grouped together
in one or even more ways.
Up until now, we have only considered
what we call impulsive actions.
But we have two more main types of sound-producing actions--
sustained and iterative.
The sustained actions are defined by continuous energy
transfer, and such actions typically
lead to a continuous sound.
Here, I have brought a kazoo as an example instrument
of sustained actions.
But the same principle applies to most other wind and brass
instruments as well as string instruments.
So in an instrument like this, we
have a continuous excitation leading to a continuous sound.
One important element here is that the performer is also
in continuous control of the sound,
while for an impulsive instrument,
the performer cannot do much to change to sound after it has
been played.
But here we can do, while playing.
The third group of sound-producing actions
is called iterative.
This is, in many ways, a combination of the two others--
impulsive and the sustained.
Iterative instruments are often based
on some kind of continuous excitation, but in such a way
that there's a rapid succession of impulsive attacks.
One example is the cabasa, which I have here.
So to summarise, we have three different types
of sound-producing actions with different motion energy
profiles and sound profiles that match these-- impulsive,
sustained, and iterative.