So in module four of the course, we're going
to dealt into more depth in synthesis, and signal processing.
how do the audio effects that we looked at in module two actually work?
and how do the the virtual instruments that
we that we're using in module three actually work?
How does all this stuff come together to actually make sound, and transform sounds?
so we're going to be looking at the, the, the theories behind this.
And we're also going to be implementing this
in a form of some simple synthesizers and audio effects you can use inside of
[INAUDIBLE].
In this first video, I want to talk
about the basics of synthesis and signal processing.
what they are, what the difference between them is.
And some of the reasons we might want
to implement our own synthesis signal processing systems.
And some of the challenges we might encounter in doing so.
So synthesis is essentially, generating audio from scratch.
so not going out with a microphone and recording it and then editing it or, or
editing it or doing something with it.
But generating it from scratch, by either analog or digital means.
so, you can, imagine we have this waveform here.
like the ones we've been looking at through the whole course.
And you can imagine that we're generating this entire wave form from scratch.
on the computer.
So how would we actually do that?
it's it actually goes back to, to what we talking about
in the very first lecture in the course. This notion of a waveform as a function.
Like y equals sine x or something like that.
you can imagine that we can synthesize a sine wave.
since no perfect sine wave is, is ever
going to exist that we can capture on a microphone.
we'd have to synthesize this from scratch.
and so we can simply use this function, sine
x to figure out what the amplitude value should be.
e, every sample over time.
so this is a fairly straightforward example
of synthesis of making a sine wave.
it turns out there's a lot of different techniques that we can
use to synthesize sound, beyond just a sine, a simple function like this.
That can give us more flexibility and power to shape what that
sound is actually going to be like, what its temper is going to be.
and so in this, in this module, we're going to look at four types of synthesis.
there are many more, but these are four
very important ones.
Additive Synthesis creating sounds by adding together a
bunch of sine waves or their basic wave forms.
Subtractive Synthesis which is kind of the opposite, starting off with
a very rich sound source like a white noise for instance.
And then filtering it and kind of sculpting it.
Modulation Synthesis which is using an
oscillator like sine oscillator something like that.
To actually could envelope they controls some other
parameter of sounds.
and Granular Synthesis which is about looking at
a sound symmetry in terms of wave forms.
But as the tiny grains these tiny little bits of few milliseconds each.
And and and creating tens or thousands of these every second
to create this notion of kind of cloud sound or texture.
so that's what synthesis is, is and some, some basic
types of synthesis.
so what is the difference between synthesis and signal processing then?
signal processing is about a transforming existing audio.
The same way we've done when we've added audio effects to tracks and Reeper/g.
the same way that effects pedals work when we plug our guitar into an effects pedal.
Now we get in some kind of source audio and
we do something to it to send the transformed version out.
when we do this in the, the digital domain we tend to call it DSP.
That's Digital Signal Processing.
and a lot of the same techniques that we looked
at on the last slide here additive, subtractive, modulation, granular.
these mostly can be applied to signal processing as well.
so they can create sound from scratch, but we can also adapt these these techniques.
To process existing sounds, and we'll look at both of these approaches throughout
this module.
So why would we actually want to
synthesize in particular our own sounds from scratch?
why not just use kind of what's out there already
or why not just get musicians that play violins, pianos, guitars.
And all that, to just come into the
recording studio and, and record them with microphone.
there's a bunch of different reasons we might want to do this.
I want to highlight two and give
you some historical examples of why this has
been important to, to composers over the years.
The first reason is a question of control
and, and precision, really that goes along with this.
This notion that, human beings can't play perfectly quantized rhythms.
Like the ones that we, we created when we, when we edited MIDI data in Module Three.
or, a composer might want to create incredibly
complex, rhythms like the, the, the tempo relationships that
[INAUDIBLE]
did with his player piano rules in his player piano studies.
these are things that are incredibly difficult, or perhaps,
impossible for human musicians to actually realize with complete precision.
computers, on the other hand, are very good at
doing exactly what they're told, and realizing things very precisely.
and so, if we, if we work with
synthesized sounds that we can control, via MIDI sequencer.
Or via, computer algorithms that we might write ourselves.
it gives us a degree of control over every aspect of the music
that, that we might not have if we, were simply, writing a musical score.
And then handing that off to
other musicians to perform on conventional instruments.
one example of this that I, I really like is a piece
by Milton Babbitt, called Ensembles for Synthesizer from, from the mid 60s.
and this was a piece written
at the Columbia Princeton Electronic Music Center.
this was one of the first centers for the study
of electronic music based at a university in the United States.
And when, when it was founded they, purchased this, this
incredible synthesizer called the, the RCA Mark II.
and this was one of those things that took up an entire room.
It was not a digital synthesizer, it was an analog synthesizer.
but you can control it with this this kind of paper tape that went through it.
It controlled all these different parameters about
the sound that you were making very precisely.
not just the rhythms and the pitches, but also very
precise aspects of the timbres and ho those timbres were created.
And Milton Babbitt, perhaps more than anyone else
really fell in love with this the synthesizer.
Because he he was using these complex
approaches to organize and structure every aspect of his music.
And so, he often wrote for human musicians on conventional instruments
but he found the RCA let him achieve his level of percision.
and kind of realize these structures in ways that, that, that might
not be possible if he was if he was working with traditional instruments.
so, it ensembles for synthesizers is a great example
of the work he did with the RCA Mark II.
The other reason that I wanted to point out that people might want to Synthesize
their own sound from scratch is they want to create a completely new timbres.
New sounds that don't exist in the physical world in any way.
And, and a classical example of that is a composer who's, his name is Edgar Varese.
Who is considered by many to be a, the,
one of the, the founders of, of electronic music.
Even though he, he didn't have access to technologies
to make electronic music for most of his life.
it was only at the very end that
he was able to create some works with electronics.
but, throughout his entire career as a composer, he was exploring ways
to make new sounds and performance and to think about sounds differently.
and, and this piece That he finished in
1931 called Ionisation, is a great example of that.
It's, it's a piece that's only for percussion.
so there are, there are no real
traditional instruments in the ensemble he composed for.
and even within these percussionists that he, he wrote this music for,
there's some traditional percussion instruments like
a snare drum, things like that.
But there's also some instruments that you might not have thought of as instruments.
Like a siren for instance, and what he was really trying to do was to to
create new kinds of timbres, and sounds that
you, you didn't normally think of hearing in
a concert hall. you know when say an orchestra played.
It's really expanded the pallet of timbres that we thought of as
being musical and to particularly think of how to organize those timbres musically.
his, his notion of organized sound is still an
idea that's important in, in electronic music composition today.
so I think ionization is, is this great early example kind
of a pre-electronic example of this, this search for new sounds.
that ultimately led musicians
to, to turn to synthesizing sounds in
order to create these radically new things.
Now, I want to follow up that idea about the
search for new sounds a timbres with a caution.
And this comes from one of the pioneers of computer
music, who developed some of the first languages for computer music.
And I think this quote really sums it up beautifully,
Max Matthews, it is very hard to create new
timbres we hear as interesting and powerful and beautiful.
What he's really trying to say here is that, you know, anyone can sit down
and, and, and, and, and create a
synthesis algorithm and you know, create a synthesizer.
but the overwhelming majority of these new sounds that
you create with the synthesizer, are going to sound horrible.
They're not going to sound musical, nobody's really going to want to use them.
whats the real challenge here is, is, is, not making something new.
But making something that's worth making that's new and that's
really where the challenge of synthesis and sound design comes in.
And where some of these techniques we're going to explore in the coming
videos they may feel very simple and limited as we look at them.
But as we see how they can be extended in, in different ways.
We'll see how they,
that they can really become rich ways of synthesizing sound
that that, that had the potential to, to meet this challenge.
so what we've looked at in this unit
is is what synthesis and what signal processing is.
And, and some of the, the issues and, and motivations behind using them.
before we start writing our own synthesizers and signal
processors, I want to look at a very fundamental idea,
that's required to do that. and that's the notion of a unit generator.