When working with the DAW and with sound in general, it's useful to have kind of a
visual representation of sound. And because sound is a longitudinal wave,
it becomes very hard to visualize it or display it in that format.
So we tend to use three different displays to give us a good visual of
sound. And I really believe that having a good
visual representation can really help you hear and understand what you're hearing.
It also is almost necessary if you want to start relating these numbers
we've been talking about to the sounds. And by the numbers I'm talking about all
these frequencies. Frequencies.
You know, people talk about 5K, or 2K,and 1K.
And, if you've never seen the numbers, it's very hard to relate it to what
you're hearing. So, I really believe that have a good set
of visual eyes and understanding what you're seeing can really help you hear,
and will make you a better music producer.
So in this segment we're going to look at three different ways to visualize sound
and why are they useful. The first is an Oscilloscope display, and
this really is like the waveform display on, in your DAW.
If you zoom way in. And you see the wave form.
You recognize that up and down is amplitude and horizontally is time.
And really we're representing the compression rarefaction of sound.
And that wave form is actually the exact path that the speaker's going to make
when sound is eventually made in the air by the speaker.
So, the oscilloscope display is really important, and the first one we look at.
After that we look at the Spectrum analyzer.
The problem with the oscilloscope display is its had to tell what the frequency of
the sounds are. because you would have to see how many
times it changed per second to figure out what the frequency is.
So while it's good its giving us an accurate representation of what the
speakers movement's going to be. It doesn't give us a good idea of the
frequency or timbre of the, of that moment and that's where the spectrum
analyzer comes in. In a spectrum analyzer, on the horizontal
we're going to see frequency and vertically we see amplitude.
And so that way we can see that this sound has a lot of energy at 2K or 1K or
500 Hz. So its going to be really useful in
associating the, those numbers to what we're actually hearing.
Problem with the spectrum analyzer, it doesn't give us a sense of where things
change over time. It's kind of a momentary picture of the
sound of the frequency and the amplitude. So when we want to get the full picture
of sound, we move to a Spectrogram analysis.
Which is like the spectrum analyzer, but repeated over time.
So we can get a sense of how the timbre, the frequency, the amplitude, all change
over time. And I think this one most represents the
way we really hear. and it's a great view and we're going to
explore all three of those right now. >> Here, we have the three main sound
visualizers that you'll find when working in a DAW.
The first one on top is our Oscilloscope display and this shows us, kind of, a
microscopic view of what's going on with sound.
It's like a very, very zoomed in, real time display of what you see in an audio
track. We'll see that one the time scale, which
is the horizontal access here, in this display we have roughly 50 milliseconds.
We can see that 48 milliseconds is listed right here.
So this is a very, very fine snapshot of time.
And it's showing us exactly how the pressure is varying in the air or the
voltage is varying in a wire after it's been converted in a microphone.
We'll see that if I play a tone, and I'll play the C below middle C, [SOUND].
I'm playing a sine wave, which we consider to be the simplest of wave forms
because it's energy at a single frequency.
And in this display, if I hold a single note, we're going to see that there are
seven repetitions of this waveform in the display.
I can change the amplitude of the signal. And we see that the height of that
waveform is changing. Representing less pressure variations in
the air, or less voltage variation in a cable or wire of some sort and I can
bring that up. Now it's important to note, as I change
amplitude, it does not have any effect on the frequency.
If I were to play a higher note [SOUND], we're going to see that, now I went an
octave up. And we're going to see that there's twice
as many repetitions here. So if you go up an octave, that's going
from the C below middle C up to C again. You'll see that you're going to have
twice as many repetitions in the same amount of time.
So, an octave, in notes, so going from C and up an octave to another C is the same
as doubling frequency. Notice, as I change frequency, it does
not have an impact on the overall amplitude.
The final thing we can see with this, is going to be a change in timbre.
So, I will now morph this waveform from being a sine wave to being a sawtooth
waveform, and we can see how that changes in the ocilloscope display.
[NOISE] So, we have the same exact pitch. I'ts still C, I still perceive it and I
still recognize it as the same exact note.
But the sound is dramatically different. And that change in sound, is what we call
a timbre change. Right, that's one aspect of timbre is how
much brightness is added to the sound. but you'll notice that changing the
timbre did not effect the amplitude and it did not effect on the frequency.
The next visualizer we will look at is the Spectrum Analyzer.
We have in the bottom left hand corner here.
Again, the Spectrum Analyzer is showing us frequency horizontally and amplitude
vertically. Let's try some of those same exact
experiments. I'll start with a sine wave [INAUDIBLE]
the C below middle C. [SOUND] Now, here, instead of seeing the
actual motion of. Of the sound or the actual pressure of
the air. We're seeing the exact frequency that,
that's at. So we see a peak right at 130 hertz.
We also see amplitude on the vertical scale.
If I was to change the amplitude of the sine wave, we'll see that bump will raise
and lower. Now one aspect of spectrum analysis is
that even if you have energy at a single frequency it shows up as kind of a wide
bump in the analysis. Now that's just a limitation of spectrum
analysis in general. So don't worry about it, it's still
energy at a single frequency. If I was to increase the frequency of the
sine wave. So like before, I'll raise it by an
octave. [SOUND] We're seeing that, that bump
moved up double the frequency. So now its at 261 hertz, and frequency is
shown again on the horizontal plane. Now the last thing we'd like to try with
this is to change timbre and see how that is reflected in a spectrum analysis.
So I'll morph this into a sawtooth waveform [NOISE] .
And we see that timbre is shown as a series of peaks in the spectrum analysis.
Now this is a very important concept in sound.
In that any periodic waveform, like a sawtooth waveform is going to have peaks
at a number of frequencies. And each of these frequencies is an
integer multiple of that fundamental. So this is at 261 and then we're having
two times that frequency, three times that, four, five, six, seven, eight, etc.
This is called the harmonic series and it's a major function in timbre.
In that the difference in sound between a sine wave and a sawtooth waveform.
Or even between a piano and an oboe playing the same not, is going to be the
relative levels of the partials. That's not the only thing that describes
timbre, but it's a very important thing. And it's much easier to see here in the
spectrum analyzer than it is to see in the oscilloscope display.
You will very often see spectrum analyzers in EQ's because the role of an
EQ is to manipulate the timbre. Manipulate the spectrum and there is a
direct correlation between what you do in the EQ and how the sound changes within
this display. The final view we're going to have in our
analysis, is going to be a sonogram display.
And hopefully as you've been watching this, you've kind of seen how this is
functioning. In that we can see all these different
parameters at the same time. The sonogram analysis is really like a
spectrum analyzer flipped on it's side. In that, instead of having frequency left
to right, frequency is up and down. Then we have time going by slowly
horizontally. This is like a zoomed out wave form
display. Kind of, in that we see instead of having
the 48 milliseconds we had in the oscilloscope display, we have showing 6
seconds here. Let's try similar experiments and use the
sonogram display. I'll play a sine wave.
[SOUND] We're going to see one horizontal bar.
And if I change the amplitude, we're going to see the color of that bar
change. It's going to fade out and be a little
more blue. And if I increase the amplitude, it turns
green. And we also see over time how that
amplitude changed. And that's the beauty of the sonogram
display. Is it gives us a history of how the
timbre and how the spectrum changed. If I play up an octave like before, we're
going to see a rising line, right. So we see frequency as vertically, and we
see the same exact thing going up an octave double the frequency.
If I change the timbre by bringing in the upper harmonics by converting this into a
sawtooth wave form. We're going to see those additional
harmonics up here as additional lines in the sonogram analysis.
And I can bring those in and I can remove them and see that upper end and how that
changes. And I can see how it changes over time.
So we see how all this functions with a simple sine wave and sawtooth waveform.
What if we use more complex sounds? How can these function for us?
Well, this next example, I'll use simple vowel sounds and show how they actually
change in the sonogram analysis. So I'll just sing.
A E I O U on that same exact note and we'll see what changes with those
different vowel sounds. Here we go A, E, I, O, U.
So, we see in the sonogram analysis, we can really see that, when I sing on a
single pitch, I'm in I'm singing in that kind of C, below middle C.
We're seeing a single, what we call fundamental frequency, which is the note
that we perceive as the note, and we see all the harmonics.
Now, one of the great things is Every little variation in that fundamental
frequency is also seen in the upper harmonics.
And that's variations in pitch because we're seeing it change on the vertical
scale. Now, it's very obvious what is changing
between our vowel sounds. This is A, and we see that the letter A
or the vowel A has a kind of a void. We're missing the frequencies around one
kilohertz. E has an even wider void around 1K.
I has a lot of energy around 1K, in fact there's a very distinct, powerful
harmonic around 1K. And we see changes in a variety of ways.
And U is a complex vowel sound, in that it changes sound over the course of the
note. And we see that changing kind of filter
shaped with that, that emphasis change over the course of the vowel.
So we see in this, that we have a single device our vocal folds, that's actually
creating the pitch. And the mouth's creating kind of this
complex filtering. It's removing and emphasizing certain
portions of the frequency range. And we can think of the mouth as kind of
an EQ, a complex filter and the vocal folds as being kind of an oscillator or a
sound creator. So I hope this demonstration has helped
to show how these three parameters of sound, amplitude, frequency and timbre
interact and are displayed on these three different displays.
Let's review. If I play a note at a single frequency,
which is a sine wave [SOUND] and I change its amplitude, we see it as a vertical
change on the oscilloscope. We see it as a vertical change on the
spectrum analyzer. And we see it as a color change in the
sonogram display. [SOUND] If I change frequency, we see it
as changing the number of repetitions within the oscilloscope.
We see it as a horizontal motion in the Spectrum Analyzer.
And we see it as a vertical motion within the sonogram display.
If I change timbre, we see it as a change in wave shape on the oscilloscope.
We see additional energy and additional frequencies shown in the spectrum
analyzer. And we see additional lines show in the
sonogram display. Remember those additional energies are
called harmonics and they're integer multiples of the fundamental frequency.
I hope this helps to kind of solidify in your head how these parameters work with
each other and how the displays work. And hopefully the next time you see
these, they'll make much more sense. Again, I think it's important to start
getting a correlation between what you hear and some absolute numbers.
And these displays will make that much, much easier.