It seems that no matter how much there is to learn
about repairing, mixing, or mastering your music, low-end frequencies and how to control them
remains a pivotal challenge for emerging producers. So, let's demystify some of the science
behind how low end is perceived in our ears and in a studio environment, and give you strategies
towards achieving a defined and balanced low end in your Productions. Now, speaking of perception,
what if I told you that the entire time I've been speaking, we've been running a 50 hertz sine
wave underneath this video? Surprised? You shouldn't be. Low end is hard to hear unless you
have the right equipment, and to some extent, the right mindset. Many of our audio devices like
laptop or smartphone speakers may not accurately reproduce low end information, like the tone that
you just heard. Even some headphones may struggle to accurately represent low end in a way that our
ears can perceive. So, now would be a really good time to throw on some good quality headphones or
fire up your loudspeakers because more examples like the one I just mentioned are coming. And
listen, if there's one takeaway from this video, it's that your ears, your room, even your gear
can prevent you from successfully perceiving low end. But, if you're armed with the right
knowledge and tools, you'll begin to overcome these low end challenges. So, let's define the
first hurdle towards controlling the low end. Thank you, your ears. Now, first, what am I
talking about when I say low end? Think about the controls on your car's speaker system. That bass
control adjusts the low frequencies, the lows, and the treble adjusts the high frequencies,
the highs. Some even have control over the frequencies between the lows and the highs,
aptly called middle frequencies or mids. So, when I say the low end in the context of
audio work, I'm actually only referring to the frequency range spanning between 0 and 250
Hertz. Anything above this would be typically considered low mid-range, and above that,
upper mid-range, and on and on, all the way to the highs. You can see low end encompasses
frequencies that are more felt than heard, where the more fundamental or tonal frequencies
of most instruments can be found. It's this 0 to 250 Hertz that's so difficult for producers to
hear and ultimately control. Now, you may have noticed earlier that this 50 hertz sine wave was
still a little hard to hear, even after I revealed it to you. Much harder to hear than my voice.
The human ear doesn't actually perceive low end elements like sustained bass or 808s to be as loud
as mid or high instruments like my voice, which, as you can see, spans a wide frequency range on
the musical frequency chart. Okay, so let's see this in practice. Let's play that 50 hertz tone
again. Try to internalize how loud it feels. Yeah, now I'll play an upper
mid-range tone at 2.5 kilohertz. It seems that controlling low-end frequencies is
a challenging task for emerging music producers, despite their extensive knowledge about repairing,
mixing, or mastering music. In this video, we will demystify the science behind how low-end is
perceived in our ears and in a studio environment, and provide strategies for achieving a
balanced low-end in your productions. Speaking of perception, imagine that a 50-hertz
sine wave has been running underneath this video the entire time I have been speaking. Low-end
is difficult to hear unless you have the right equipment and mindset. Audio devices such
as laptops or smartphone speakers may not accurately reproduce low-end information, and even
some headphones may struggle to represent low-end in a way that our ears can perceive. It would be
a good idea to put on high-quality headphones or fire up your loudspeakers at this point because
more examples are coming. Your ears, room, and gear can prevent you from successfully perceiving
low-end, but with the right knowledge and tools, you can overcome these challenges. Let's define
the first hurdle towards controlling the low-end, which is your ears. When we talk about
low-end in the context of audio work, we are referring to the frequency
range spanning between 0 and 250 Hertz, where the more fundamental or tonal frequencies
of most instruments can be found. This frequency range is challenging for producers to hear and
control because it is more felt than heard. The human ear perceives low-end elements like
sustained bass or 808s to be less loud than mid or high instruments. To see this in
practice, let's play the 50-hertz tone again and internalize how loud it feels, and then let's
play an upper mid-range tone at 2.5 kilohertz. Which one sounded louder to you? Well, technically
they're both playing at the same loudness of 10 decibels each, but that 2.5 kilohertz that sounded
way louder than the 50 hertz tone, didn't it? So, what's going on here? The human range of
hearing spans from around 20 to 20,000 Hertz, and through a number of interesting experiments
over the years, us humans have discovered that our ears are especially sensitive to sounds residing
in that upper frequency range, and much less sensitive in the lower range. Even though both
sine waves were played at the same loudness, one sounds louder than the other and always will as
shown by the Fletcher Munson equal loudness curve. So, this is the first thing we need to remember
and internalize - our ears are biased toward higher frequencies than lower frequencies, even
if the sound source is the same scientifically measurable loudness. This is why audio engineers
use a different loudness standard than decibels (dB) when they're mixing and mastering music.
It's called L-U-F-S, and it takes into account this skewed perception of frequency. In fact,
we're especially sensitive to 3.5 kilohertz, and some say this is likely due to the resonant
frequency of our ear canal. Using iZotope Insight, you'll notice that the 50 hertz tone and the
2.5 kilohertz tone have different LUFs readings because LUFs takes into account that human
perception of the loudness. The 50 hertz tone, according to the LUFs reading, is
quieter than the 2.5 kilohertz one. So, what does this mean for you, the producer?
Well, I can tell you what it doesn't mean. That you should turn low-frequency content up in
your mix so that it's as loud or at the same LUFs level as stuff in the upper mid-range like
my voice or a snare drum. Don't do this. In fact, the tendency to crank low-frequency content
will just flood your mix and lead to a low-end swampy mess, which might be why you're
watching this video in the first place. Now, I'm not saying never turn your low end up. In
fact, it's certainly true that low end has risen in loudness and prominence across the history of
recorded music from the tin foil phonograph to today's digital streaming file formats. These
technological advances have led to more room, essentially, for low end. It used to be
that if you had too much low end in the LP, the stylus would just jump right out of the
groove. But in the days of digital streaming, much more low end can be present in a
recording without breaking the technology, so to speak. But with the rising level of low
end in commercial mixes, you need to figure out how to properly manage it if your mixes are going
to compete with professionally produced material. Okay, so that was a lot. Let's summarize. Humans
are less sensitive to low frequencies and more so to high and mid frequencies, as shown by the
Fletcher Munson equal loudness curve. Audio engineers use LUFs as a loudness standard, and
you should too, to account for our sensitivity to mid frequencies. The rising level of low end
in recorded music means that producers like you have to learn how to properly manage this mix
element in order to compete with professionally produced material. So now that we've talked
about what low end is, what I mean when I say it, and how our ears perceive it, let's pivot to
how it behaves when you're producing music. In an acoustic environment, like your bedroom
or project studio, your monitors (in audio production, we refer to the speakers as mono
monitors) - now, when shopping for studio monitors, it's important to invest in a pair that
reveal as much mixed detail, at an even frequency response across the 20 to 20K audible frequency
range, as is possible. Treating your room (I'll talk about what that means in a moment) is
important to get the most out of those monitors. For the best low-end reproduction, you'll want to
use a loudspeaker that represents low frequencies accurately, so ideally, you're investing in a two
or three-way near-field stereo speaker design. Let's take a second to talk about near-field mains
and other popular monitors. Those giant speakers that you see in studios that are sometimes flush
with the wall are known as studio mains. Now, they're extremely expensive, and many engineers
rely on them only for precise EQ tweaks. This is because the smaller near-field monitors that we're
going to focus on in this video are closer to a true average Joe consumer listening experience.
So, this means that something like those cubes or the ns10s aren't going to spit out low-end
well enough to make critical mixing decisions. Now, some engineers look to things like special
cone vibrations in the ns10s for clues about low-end health, but actually hearing the low end
is really important. Now, you might be wondering, do I need a subwoofer, which covers around the 20
to 150 Hertz audible range? I mean, I say audible, but really, that stuff down there is more felt
than heard. As you'll remember from our previous chapter, a sub isn't always necessary, but if you
want one, make sure to get one that's made by the same manufacturer as your larger stereo monitors,
and do some research on how to calibrate and place the subwoofer in your space. Having it below the
desk, on the floor, in between the left and right monitors isn't always the best location, so
experimenting with its placement is crucial. A quick word about enclosures - you'll often see
monitors with a hole at the bottom. That hole, sometimes called a port or a vent, is
essentially a resonator for low-end. Holes like this make the bass really come
alive and sound boomy and powerful. Now, this resonator might be ideal for impressing
clients in your studio or impressing you, the producer, on the showroom floor, but honestly,
I'd encourage you to experiment with plugging that hole with some foam or another material to see
what sounds better to you, specifically in the low end. In fact, my loudspeaker comes with
plugs that fit snugly into the port. Closing the port can often deliver a tighter bass
sound, which, in my personal experience, is better for my mixing and mastering work
here at home. So, something to think about. At the end of the day, when shopping for
your monitors, it's really important to listen to as many as you can and ideally test
them in your space because when manufacturers develop their monitor, they don't test
them in DJ Dave's basement studio. They actually use anechoic chambers, so it's
really important to keep in mind the role your own space plays when considering
loudspeakers, especially for low-end. Let's recap: look for monitors with an even
frequency response across the audible frequency range for accurate low-end representation. Try
going for a two or three-way near-field stereo speaker design. Those Oritone cubes or Yamaha
ns10s aren't really suitable for hearing low end. Subwoofers are not necessary, but if you buy them,
make sure to get the same brand as the larger stereo monitors and experiment with its placement.
Also, experiment with plugging the ports or the vents on your monitors for a tighter, more polite
base. Lastly, just test your monitors in your own space if you can because manufacturers test theirs
in anechoic Chambers, not bedroom Studios. Now, speaking about low end and how it behaves in your
average Studio, let's move on to the next section. For everything we've said about loudspeakers,
they're honestly useless without some form of room treatment, and low end frequencies can
be especially troublesome to control. When low end frequency content leaves your monitors, it
travels in all directions like ripples in a pond, and when this low end reaches a surface like a
window or a wall, it creates a new Sound Source at that point of contact, almost as if you've
placed another speaker there altogether. This creates what's called a standing wave, which
is a sound wave pattern created when sound bounces back and forth between two surfaces
in a confined space, such as between two walls. You've essentially confined it such that
it's bouncing back and forth, looping almost endlessly until you turn the monitors off. These
waves can interfere with each other and combine, causing certain frequencies to be either amplified
or attenuated at different points in the studio, resulting in resonant frequencies
called room modes. And these room modes don't just happen horizontally, right? They
can actually happen from all angles of the room. Now, to make these matters worse, according
to the laws of Acoustics, when a particular frequency is caught in that resonant Loop, all
of its related frequencies, known as harmonics, are also confined. For instance, if the
lowest resonant frequency is 50 hertz, then its harmonics, including 100, 150, 200,
250, and so on, will also be confined. The bad news? The deepest resonant frequencies happen
to be the most impactful ones when it comes to small rooms. These lower frequencies
fall within the range of our hearing, meaning you're going to hear these modes,
and you could be fooled into making really bad decisions because you can't tell
that the room is affecting the mix. So, what can we do? Keep your speakers as
far away from the walls or any boundaries as possible. The closer they are, the more low
end builds up. You should consider investing in absorption and diffusion. This is back when I was
talking about treatment. The purpose of diffusers is to disperse Sound Energy, even low-frequency
energy and standing waves. On the other hand, absorbers work by absorbing Sound Energy, thus
avoiding the creation of those trapped Loops that we discussed earlier. Absorbers are
especially helpful for really small rooms like the one that I'm in, and the reason is
simple. If we absorb sound as it hits the wall, we damp the reflected energy and therefore
minimize the effect of standing waves. Now, to prevent vibrations from affecting
those monitors, products like isolation pads, and these are sometimes made from foam
or spikes, are commonly used to separate monitors from the surface that they're
mounted on. This is known as decoupling, and this is going to ensure that
the speaker can work independently without any back vibrations from its stand
interfering with its day-to-day operation. This decoupler is often said to deliver a more
focused base response, so even after all that, and maybe even a dash of corrective room software
(which can be great), perceiving low end can still be a challenge. You might be tempted to
reach for a pair of headphones and avoid your room altogether, so let's talk a little
bit about headphones and low end perception. With headphones, you get to kick the room modes
(standing modes and even flutter echoes - more on those in another video) to the curb. When you
pair great headphones with a great headphone amp, the low end from around 80 to 400-500 hertz
can be solidly reproduced. Other issues, like cone filtering from early reflections, or
worrying about sitting in the perfect spot in the equilateral triangle, those are moot. Even
the directivity of the tweeters not hitting your ears perfectly based on your posture or lack
thereof totally disappears with headphones. I say, embrace them, especially for referencing
low end in a room with flawed acoustics. What's more, you and everyone you know uses
headphones to listen to music these days, so it's good to hear what they're
hearing and tune your mix accordingly. So let's sum up: loudspeakers are useless
without some form of room treatment. Low end can be difficult to control because it spreads in
all directions, creating new sounds or standing waves when they reach different surfaces. Standing
waves interfere with each other and cause certain frequencies to be amplified or attenuated. These
are known as room modes. To prevent room modes, keep speakers away from boundaries and
invest in absorption and diffusion. Isolation pads can prevent vibrations from
affecting the monitors. Headphones can be a really useful tool for referencing low
end in a room with flawed acoustics. Now that we've gone over the acoustic and
psychoacoustic background of low end and how to manage it in the physical world, how the
heck do we manage it in the digital realm? Most would agree that you should mix with your ears
and not your eyes, but we can't compete with the hearing range of bats. And as I mentioned, and
has become the theme of this video, our room, our ears, even our gear can work against us.
Because of this, meters become a useful tool for confirming or denying what we think we hear
vibrating through the air, especially those low end vibrations. In the last 10 years, metering
has really evolved from level and/or phase to displaying energy, width, tonality, and more.
Let's get some music playing through a variety of meters and settle on the one that best
represents low end in the most helpful way. You might be familiar with phase meters that
measure the phase coherence between the left and right channels of the mix. Now, this meter
is good for determining if my mix element is in or out of phase, which has some low end
implications, but what it doesn't tell me is if my low end is too boomy or too flat or totally
chaotic. Another meter, known as the level meter, measures average or peak loudness. They
can sometimes look like this or this, which is a VU meter. Now, these meters,
while useful on individual tracks and mixes, tell us very little about what's going on in the
low end of a mix. So let's get a better metering solution for this task. You might be familiar
with the spectrum of an EQ, which measures frequency energy from that human hearing range
we've been talking about (20 to 20,000 Hertz). It's basically another way to view energy spread, like we saw in our musical frequency chart.
This kind of metering can tell us way more about the health of our low end than the
phase or level meter. But what this meter won't tell us is whether or not the low end is
working for the genre you're producing music in, because different genres have different tolerances
for low end. This is why we invented at iZotope Tonal Balance Control. Now, we've made loads of
videos on Tonal Balance Control, but in short, it displays the health of your track's frequency
balance across four key areas, from lows to highs, and it's an effective way to see your low end -
literally see it - when your environment might be working against you acoustically. You'll see both
fine and Broad views with our zero to 250 Hertz low end we've been talking about this whole time
represented in its own quadrant right here. And if you play your track with Tonal Balance parked on
the master bus, this white line is going to show your mix while the bluish-green blob shows the
typical range of energy in each frequency band. Now, here's where iZotope Tonal Balance Control
is especially helpful. By flipping through the genre targets, you can see how your low end
lines up across different genres, because different genres have different allowances for all
kinds of content, but certainly for low end. And just so you know, these targets were informed by
analyzing thousands of amazing sounding songs on the streaming services today. And you can actually
upload your own and have Tonal Balance create custom curves or whole folders of songs as well.
So, how can we affect low end frequency content and keep within the bounds of one of these genre
targets? You can actually remote control level and frequency from the drop-down menu here without
having to have a bunch of plug-in windows floating around. If your bass or kick drum feel too loud
and they're contributing to some spikes in that range, you can just call up Ozone or Neutron and
balance until you get a solution that you like. Now, we're going to look at this more in
a moment, but it's also worth pointing out that iZotope makes Audiolens. This is an
app that listens to your computer audio, including a streaming service playing your
favorite reference track. It's going to capture the tone, level, width, and dynamics, creating
a profile - a custom genre target, if you will. And you can use that target to inform Ozone's
Master Assistant or Neutron's Track Assistant. But first, let's tackle the
much larger issue of balance, form, and definition - largely depend on the
work done in this busy low end region that we've been obsessing over in this video. It's usually
cluttered with non-essential content. It's also where the fundamental frequency or lowest note
of many instruments tend to live, after which the overtones or timbre of the instrument follow.
This fundamental is really, really important. Now, when I said non-essential content
earlier, what do I mean? Well, let's head back to our musical frequency chart. If we
were to give dedicated frequency ranges to the typical instrumentation found in many modern
mixes, that might look something like this. Now, let's adjust the ranges to reveal the actual
frequency content of all those instruments. Not so clear and tidy anymore, is it? We now see a
mixed scenario where common instruments like bass, kick, snare, piano, guitars, pads, vocals have
frequency content extending into that sacred zero to 250 Hertz range. Now, as a mixer,
it's your job to bring tonal balance to your mix. And to be successful, you need to
determine what's meant to be in that range. Well, remember this chart: bass and kick
typically own this area, and how much or how little can be genre-dependent. Many tracks
in modern mixes have low and low-mid energy that, when taken away, don't affect the identity of the
original signal. And by removing this energy with a high-pass filter, we're decluttering the low
end overall. And if you're wondering how much to cut with a high-pass filter, take a look at some
of the presets included in Neutron. Most have a gentle slope cutting low end already, so you can
use this as a starting point to trim further from there. Try bringing up the filter until the body
of the track feels too thin, and then pull it back to where the most important tone of the track
still remains. Anything below that range would be needlessly contributing to your low end.
Use your ears and trust yourself. So let's investigate this in a mix that I have here that's
kind of country pop. Take a look, you're right. Using Neutron's EQ Spectrum, I'm going
to look and listen, and then high-pass, allowing the highs to pass effectively cutting
the lows from sources that I think are needlessly obscuring the low end. This is hopefully going
to bring our zero to 250 Hz zone into focus. Internal balance control, and I'll use some
gentle filters to accomplish this work. Now, all this subtractive EQ work can be a bit
scary and feel strange, right? After all, we want to add energy to our mix. Think about
a friend who just had a haircut. It could be shocking, but if you give it a day or two,
you'll start to maybe notice more definition in their facial features. That's kind of what
I'm talking about when I say cut stuff out, subtract, clear away to add definition. By giving
haircuts to your tracks and removing information, you're actually revealing what's most
important and keeping things under control. I've identified the following sources
as needlessly contributing to my low end in this song: the percussion loop,
some of the stomps, acoustic guitar, electric guitar, and the synth. And even
the bass felt a bit subby. So I rolled off some of that subsonic information
with gentle filter slopes. In fact, I use gentle filter slopes all across my
high-passing work. So here's the next before: "Where you belong, you're
right where you belong here." iZotope Tonal Balance Control tells us
that we're in the bounds for healthy low end given our country target, which is where
I think this track kind of lands sonically. Now, you'll notice I didn't turn the bass down or
turn the kick down or turn any other instruments down. I just cleared things away. So sometimes,
volume isn't the answer. Sometimes it's just frequency pruning. So clearing away unnecessary
low-end contributors from that 0 to 250 Hz range really made a difference in terms of firming
up the overall low end of the track and adding clarity to my ears. The vocals are a bit more
intelligible, the energy is clearer, the track sounds cleaner overall. That's an example of
how to find balance and create definition. I want to speak about definition a bit more,
and by definition, I mean how distinct and recognizable the sounds are from one another.
Balancing your instruments and scooping out low-end information from non-bass instruments will
achieve more definition. But how can we take it even further? For example, now that my kick and
bass are predominantly occupying the low end, how can they be more focused and articulate? Well,
for starters, they're likely masking one another, which happens when one sound overlaps another,
causing one to be less audible. iZotope Neutron allows us to deploy our unmasking
technology which identifies overlapping frequencies and clears them up immediately
and automatically. Let's see how this works. We take a detour into jazz town for the next example. You'll see three sound
sources here: we have a bass, a drum loop, and some sax. Now, individually, these instruments are really strong,
especially the kick in the drum loop. But you'll see that when it's
combined with the jazz bass, the kick just has a hard time being heard. So, in order to tackle this low-end challenge,
what I'm going to do is place an instance of Neutron Unmask here, and then I'll also
click and drag it using option click and drag to the other track as well. I'm going
to solo these guys so that I can do my work. So, right now, the bass is kind of walking
all over the kick. So what I'll do is go to my jazz bass track and I'll select the
side chain input to be my drum loop. Now, we're not going to see anything yet, but I
just want to call your attention to the metering. Purple is my kick, the rest
over here is the drum loop, so the kick's fundamental is right here and
the white trace, my jazz bass. So let's get to work untangling one from the other, and
what I'll do is bring the unmasking in. So that sounds okay, but what I want to do is
localize the unmasking just to that area where I see the kick's fundamental in purple poking up
and down. So, I'm going to bring these bands in, prevent unmasking from affecting anything
above 142 Hertz. I'll tighten this up as well, bring this up a little bit. Monitoring the release and attack all
the way down, I want nice quick work. Sensitivity can come up just to make sure we're
safe and just catching the side chain source, and that sounds super modern. It
sounds like the kick's coming through, but I want to split the difference a bit
and just bring the mix down a little bit. Great. So now what I've done is I've unmasked the
bass from the kick or the kick from the bass. Kick sounds much more present. Let's see
what that sounds like in the actual mix. So listen to how the bass is still present and
articulate, especially in the low mids and upper mids, but in that zero to 250 Hertz range,
the kick is poking through and can be heard. And this is the work that goes into untangling
low end with unmasking techniques in a way that I think really improves the intelligibility
of certain elements in the low end. Now, there's a few other ways to bring more
focus and definition to low-end instruments. More often than not, that zero to 250 Hertz
range can't be made any louder without tilting the mix into a tubby soupy mess. So consider
using tools that excite the upper harmonics of low-end instruments, effectively extending
their fundamentals into a more audible range, allowing the listener to locate and source
low-end instruments with ease. Especially on playback systems with really bad low-frequency
response like laptops or smartphones. Of course, we have a few tools to help with this
like Low End focus in Ozone 10. Listen to the added pop and snap we can add to
the kick with some spectral contrast. Take a listen to how that 808 perks up and
almost comes out from under a blanket, foreign. Now, my last tip for controlling low end is going
to be about the mastering stage, specifically in compression. We've already produced six seasons of
our Nam Tech award-nominated "Are You Listening" series, which I very much encourage you to watch
in full, but there's one tip in particular worth repeating here. Low-frequency energy contained in
a full stereo track is by far the most transient, lots of energy. Bass drum, bass guitar, the bottom
of a snare. They can be really dynamic, meaning these instruments will often trigger a mastering
compressor more often and faster than other melodic instruments with more constant level, like
vocals or hi-hats. If the mastering compressor's threshold is pulled down, dynamic and transient
elements of a mix will cause the compressor to get to work more quickly, which could cause a kind
of pumping effect, which may not be desirable. If, to you, that's undesirable, head to the side-chain
detection area here and use the built-in high-pass filter to effectively stop low-frequency
information from triggering the compressor. By performing this move, I'm not allowing
the compressor to hear the kick, bass, or even the bottom of that snare. Let's
do a before and after and listen to how that low end is retained in the after and how it
almost brings the whole mix down in the before. What happened there, that pumping caused by
that very dynamic low end energy of the mix is effectively gone, allowing more of the
low end to come back in naturally. It's up to you to decide if you like the pumping or not.
Heck, it's up to you to decide if you liked the high passing I was doing earlier to get the tonal
balance kind of quadrant under control. My goal is just to give you tools and strategies to navigate
low-end challenges in your mix. Thank you so much for watching this video. We've reached the end,
and we couldn't cover every technique or concept related to low-end management, but I hope that
the folks who did stick around and made it to the end are going to leave a comment with their
own techniques and strategies, and hopefully, you folks now have knowledge and tools to
perceive and then tackle low-end. Take care.
