[MUSIC PLAYING]
Amplitude.
When you're looking at a two dimensional waveform display,
amplitude is the height of that waveform.
For audio signals, this equates to the sounds of loudness.
A quiet sound, like a whisper, will have a small amplitude,
while a sound with a lot of energy like a jet engine has a larger amplitude.
A good metaphor for amplitude is altitude.
We measure the height of mountains as being
a certain number of feet above sea level and the depths and valleys
of the oceans to be below sea level.
Just like sound, mountains can be formed by two elements colliding.
For sound, it might be a finger plucking a string or striking a key.
And in regards to mountains, it would be two tectonic plates
running into each other.
Depending on how much energy is behind these collisions,
the resulting sound will have a varying degree of loudness,
which is equivalent to its amplitude.
In a way, you can visualize a mountain's amplitude just by looking up.
Imagine how loud that collision must have been.
The word envelope is the one that pops up a whole lot in sound design
and can be challenging to visualize.
Think of the word envelope in its noun form.
It's what you put a letter inside of to send away in the mail.
It's a thing that is.
But since music is a thing that is happening or happens,
it's more useful to think of the word in its verb form--
to envelop.
The definition of envelop is to completely enclose or surround,
which is exactly what an envelope does.
A paper envelope encloses a letter.
And very much in the same way, the envelopes on a synthesizer or effect
take an audio signal and wrap themselves around it,
shaping and carving the sound from the moment it begins until it ends.
Similar to how a filter shapes the timbre of a sound,
an envelope shapes the evolution of a sound.
The most common envelope you'll see is an amp envelope,
which shapes amplitude over time.
But there are many other possibilities.
Another common use of an envelope is to wrap itself
around a sound's brightness.
Frequency is a word that you'll see time and time again.
Frequency is how often something occurs in a specified amount of time.
To put it in context of your life, think about how frequently you eat per day.
Three times?
Your meal frequency is three meals per day.
Or think about how frequently your heart is beating.
It typically varies between 60 to 180 beats per minute,
depending on whether you're resting or exerting a lot of energy.
In the context of music production, frequency
refers to how often a waveform repeats each second
and is measured in an increment of Hertz.
One Hertz means once per second.
If something is vibrating at 20 Hertz, it is repeating 20 times each second
and produces a very low pitch.
If an oscillator is vibrating at 16,000 Hertz, it's moving a lot faster
and produces a much higher pitch.
So frequency not only relates to how often something occurs,
but in our world, it also relates to the pitch of a note.
A good metaphor for frequency is a car engine.
As you put your foot on the gas, the engine spins faster.
And as that frequency of revolutions per minute increases,
so does the speed of the car.
As this is happening, you can literally hear the resulting rise in pitch.
Regular car engines are usually cruising between 2,000 to 3,000
RPM, which results in an exhaust pitch somewhere between 30 to 50
Hertz, which is in the lowest octaves that humans can hear.
Formula One cars rotate considerably faster, resulting in a pitch
around 1,200 Hertz, which is around an E flat six.
To reiterate, frequency is a measure of how fast a waveform vibrates,
which is directly related to its subsequent pitch.
Both of these ideas are important to keep in mind as you adjust
the frequency parameter on any device.
Oscillators are the part of your synthesizers that create sound.
Think of them as throats.
They produce electronic signal which creates a vibration that oscillates
back and forth just like vocal chords.
Oscillators use specific voices to sing with and emit wave forms, such as sine,
square, saw, and triangle--
each with their own distinctive timbre.
Some synthesizers only have a single oscillator.
But others have several which can all sing
at the same time, each with their own pitch or tone,
creating layered and multi-timbral sounds.
Filters are everywhere.
They're in our water pitchers, our air conditioners,
and our social media apps, just to name a few.
We encounter them so often that they're almost like background noise.
Speaking of background noise, we could use an audio filter
to get rid of some of that.
Let's correlate an audio filter to a kitchen strainer.
We pour a pot of pasta into a strainer, which
separates the liquid from the solids.
In our case, we're sending audio into a filter,
which is only allowing certain frequencies to pass through it,
separating the ones we want from those that we don't.
But as you might expect, filters are a bit more
elaborate than kitchen strainers.
Not only can we completely separate out frequencies we do not want,
but we can also choose to only reduce their amplitude
or increase them, allowing us to sculpt and shape the timbre of our sounds.
Oscillators tend to emit very bright sounds.
So often, you'll see a low pass filter used,
which is allowing the low frequencies to pass through the filter
and reach your ears while eliminating some
of the higher more harsh frequencies.
Another word for timbre is tone.
Timbre is the distinguishing characteristic
that differentiates one sound from another, despite the fact
that they might be playing the same frequency with the same amplitude.
When we're describing a sound's timbre, we
use words like sharp, round, reedy, brassy, or bright to describe them.
Let's correlate timbre to flavor.
Think of apples.
They're a type of fruit that has a typical shape, color, and flavor.
But inside the category of apples, there's a huge amount of variation.
Some apples are very sweet, while others are more sour.
Some are red, while others are green.
They're all still apples, but each one with a distinct characteristic.
Red Delicious is different from McIntosh is different from Gala
is different from Honeycrisp.
Even when describing one type, there might be variations from apple
to apple.
Same thing goes for sound sources.
One category of timbre we use quite often is strings.
Inside of the string family, we have violins, violas, cellos,
and double basses.
They have similar timbres and tones in some ways, but each one is distinct.
When comparing two different violins, one
might have a very bright sound, while the other is more muted and dark.
Even when playing one violin, we can produce different timbres
by bowing a different way.
LFO stands for low frequency oscillator and is exactly what the name suggests.
It's an oscillator which emits an electronic signal just
like any oscillator, but its signal is at a very, very low frequency.
So low, in fact, that it's often below the range of human hearing.
You might ask yourself, why would someone create an oscillator which
emits a sound we can't hear?
Well, the answer goes back to the idea of vibrations.
The waveform an oscillator creates travels back and forth, back and forth,
back and forth, like a pendulum.
And we can use that movement to create a lot of musical effects.
An LFO swings back and forth, but outputs a signal
that is not coloring the sound.
Instead, we use that oscillation to control other parameters.
Many common effects are created with LFOs.
If we assign the LFO's pendulum swing to a volume knob, we have a tremolo--
a repeating change in amplitude.
If we assign it to a frequency parameter, we get vibrato--
a repeating change of pitch patterns.
When we assign it to the cutoff frequency parameter of a filter,
we get a cyclic variation in timbre, which is how
we get those cool wobble bass lines.
Modulation is change.
It's a word you've probably heard when referring
to a key change that occurs mid-song.
Think of Beyonce's Love On Top, which has
four modulations towards the end of the song, each time raising
the harmonic root a half step up, creating a harmonic ascending line
cliche.
In this case, modulation is referring to change of harmony or key center.
In all the devices you load into Live, modulation
can relate to pretty much any parameters since they can all be changed.
To tie two concepts together now, the most useful modulation of an oscillator
is pitch, which is assigned to the keys on a keyboard, also known
as key tracking.
In the same way that Love On Top is moving in half steps,
as we move up the keyboard note by note, we're
modulating the pitch of an oscillator by a half step each time.
An LFO uses its oscillator as a control signal to modulate other parameters.
To go back to our previous examples, in order to create tremolo,
we modulate volume at a certain rate or frequency.
To create vibrato, we modulate pitch.
And to create a wobble bass, we modulate frequency cut off of a filter.