- We've already made some big investments
into our testing lab,
a new building, new talent,
and some crazy new equipment,
and we are finally ready
to start talking about it.
See these two heads?
They're called HATS,
or head and torso simulators.
They're for testing personal audio products,
and the ones in front of me
cost a combined $80,000 US dollars,
which is why we definitely cannot afford
to keep both of them.
- Why, why us?
No, please, I'll do anything.
Anything.
- Uh...
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The keen-eyed among you might notice
that our HATS happen to be missing the torso part,
but that's okay,
because that only really matters for speaker testing,
and we're gonna be focused
on headphones and microphones
for the time being.
Also, the torso is a plastic tub that
adds $20,000 to the cost.
So, I'll pass.
Now, understandably, you might actually
feel the same way about
the HATS part,
couldn't we just use any plastic head?
The answer is, "No."
There is a method to the madness here.
This form of hearing simulator
was first created in the 1980s
to accommodate the testing
of phones and hearing aids.
You see the thing about hearing devices is that,
depending on the conditions,
they can perform dramatically differently.
You can try this for yourself.
Lift your headphones off your ear like this.
(upbeat music)
Sounds pretty different, right?
So these state-of-the-art HATS models
from just a couple of years ago,
both claim to better represent
a headphone's real-world performance
by simulating not just the shape of a human head,
so you get a good seal,
but also even the ear canal.
Both of them are also equipped
with high-performance microphones,
allowing us to test
the full range of human hearing
with both of them costing about as much
as an actual human head.
Don't ask me how I know.
So why not just hire trusted listeners
to evaluate headphones for us?
It's because listening is a subjective experience that
can be influenced by your mood, your biases,
and even your state of mind, man.
That means that any product review that
relies solely on a human evaluator
will be inherently unreliable.
Now we could look at the spec sheet,
but a shocking number of audio manufacturers
seem to be pretty much copy-pasting
the same performance numbers,
alongside vague posting nonsense,
like, "Next-level listening,"
or, "We retain the emotion of the sound."
- Emotion!
- So I guess we can't trust them either.
What do?
If you've ever read or watched headphone reviews,
you might have seen something like this before.
It's called a frequency response graph,
and it's meant to help us visualize
the sound signature of an audio device.
The left end of the x-axis represents
the lowest bass sounds that
humans can hear, about 20 Hz,
and the right end represents
the highest treble frequencies that
humans can hear, around 20,000 Hz.
With these, we can chew through manufacturer claims
like a hot-head chews through butter.
Some might claim to have a neutral sound, for example,
but actually they have the bass cranked up so high,
it would wake up your neighbors.
To measure these numbers though,
we need to start with the right gear.
Let's get acquainted with our potential suitors here then.
Bachelor number one is the B&K 5128 Type B,
and aside from having obviously better microphones,
it improves upon its 1981 predecessor in a few ways.
For the ear canal, B&K averaged MRI scans
of 40 test subjects to give it a longer,
more human-like shape,
and instead of using purely soft rubber,
they added plastic components
to the inner parts
to represent the acoustic effect
of the bonier inner-ear.
Now, for bachelor number two, sort of,
the HMS II.3 LN HEC,
aka, the SuperHMS,
comes from HEAD Acoustics,
and by their own admission,
it is actually based on the B&K 5128, but simplified.
It has a shorter ear canal
and is made of just rubber,
resulting in slightly looser tolerances
for acoustic competence,
both below 80 Hz and above 12 kHz,
which is not ideal,
but the larger diaphragm
of the SuperHMS's microphone,
results in a lower noise floor,
which means slightly improved performance
in certain other tests like distortion.
Now there was a bachelor number three right here,
but our headphone test engineer
has actually worked with that model before
and thinks that it is "crap."
So we didn't even bother renting one.
Now, at this point, at least on paper,
it seems like the 5128 is the obvious choice,
but a lot of that is based on manufacturer claims,
which is not how our lab is supposed to work.
So we spent the last few weeks,
which cost us thousands of dollars in rentals, by the way,
validating those claims and searching for potential flaws
while looking fabulous, of course.
WAN hoodies, now in stock at lttstore.com.
As for why it took so long to test,
I'm really glad you asked.
We needed to run two sets of tests,
one comparing the heads to each other,
head-to-head, you might say,
and the other comparing the heads
to 25 of our own fleshy, guinea pigs,
I mean, excuse me, employees,
and that's for a human-to-machine comparison.
Now the demographics of our company
are not representative of the general public.
We've got a lot
of default character creation screen dudes here,
but after some adjustments
to our calculations, to compensate,
we were ready to measure the bass
of eight different headphones
on each of our human subjects.
Why only bass?
Okay, we wanted to measure treble as well,
but because treble sound waves are very short,
a 15 kHz wave is actually less than an inch,
the microphone position needs to be very precise
across all of the test subjects,
which we didn't have time to deal with
during our short-term head loans.
Bass waves, on the other hand, are very long.
A 20 Hz sound wave is 55 feet in length,
so microphone placement doesn't require
the same level of precision
across our human subjects
to acquire comparable results,
and besides, in our head-to-head testing data,
we found only small differences in the treble range
between the two heads.
So we proceeded with our human testing,
which...
Oh, oh, apparently I'm next.
Let's go.
Step one is our subject gets
to place microphones into their ears like...
How?
I don't know how. - So the first step would
be to sanitize your hands,
and also sanitize your ears. - That makes sense,
even in not-COVID times,
when you're talking like ear goop.
Ooh, look at it, go.
Wee!
- This is for the inside of your ears.
Now we have to place the microphones.
This is the left ear.
- Okay, here you do the left one,
and then I'll do the right one.
- Okay, it goes inside your ears like this.
It does not necessarily fit everyone.
For some it's a bit too small
and it just keeps coming out,
something you might be familiar with.
- This is cool.
There's a microphone right here.
These look right,
and then this little guy sits
in your ear a little something like...
And I guess it goes kind of like that.
Okay, and then this goes here.
Okay. - So then, put the headphones
on the way you normally would.
- Okay. - Then I'm going
to play a noise. (pink noise)
- Our headphone test engineer just played pink noise
through the headphones for me,
which you could think of kind of like...
Pink noise is tuned more for human hearing,
so it doesn't sound so harsh to us.
Now I take them off,
I put them back on. - Yeah.
- Every time we put on our headphones,
we do it a little differently.
Maybe the band is here, or maybe it's more like here,
or maybe our kids are playing around
with all the adjustments.
(laughing)
(pink noise)
- And that's the second test.
- Okay, and we do that five times
with every subject. - Yes.
- Now these are open-back headphones.
Is it a problem if people
are clicking their mouses and stuff?
- Again, we are not in a controlled lab environment,
so that's expected.
- They will not miss an opportunity
to remind me that the current conditions
are not perfect, I know.
Over 1,000 measurements later,
the resulting average looked like this.
So how does that match up to our heads?
The quick and dirty version is that
with open-back headphones,
we found a measurable but minor variance
between the two units,
and between our human test subjects,
but both of these are within what we'd consider
to be an acceptable range.
Our engineer isn't ready for video appearances yet,
but he will be publishing
a more detailed write-up on Floatplane,
for those of you who want to dig a little bit deeper
into why we consider that okay.
Shifting gears to a popular close-back headphone,
we see a much different story.
Look at this variance in humans at 40 Hz, 14 decibels.
That means that some people would
be perceiving more than twice as much bass,
compared to others,
completely changing the listening experience.
This is because closed-back headphones rely
on a proper seal to create their bass.
Comparing our heads, however,
again, they're pretty close,
but the 5128 measured slightly closer
to our humans than the SuperHMS.
So both heads get a pass here,
but the 5128, it gets a gold star.
We also tested some in ears that
are known to cause problems for HATS in general,
and found that this issue was present
in both of our models,
meaning that these heads struggle
to get a good seal on some larger IMs.
Two more passes, but this time with unhappy stickers,
because it means no matter which way we go,
I'll eventually have to replace this darn thing.
Really?
Any who, I guess it kind of makes sense that
our results have been so close,
given that both of these models
are based on the same design,
and that both are considered
"industry standard" testing equipment.
We do, however, have a winner...
(drum roll)
The B&K 5128's!
Some may disagree with our assessment.
Some might not think it's worthwhile
to get any head and torso simulator,
because the greater body of academic headphone research
has been done on older simulators,
and is therefore less applicable
to this new hardware,
but we feel that we can take the current knowledge base
and adapt it to the newer models
to get the best of both worlds,
the best research and the best tech.
To be clear, the SuperHMS is still an excellent product
and a major improvement over its predecessor,
but the things that pushed us toward the B&K
were its ease of use, improved durability,
and better reputation.
I'm happy with our choices,
but there's a big "but."
Here, I wanna make it clear that
our results here are not the be all and end all
of audio testing at all,
and the testing that we end up doing in the future
with the B&K 5128,
it's not gonna be the be all and end all either.
For one thing, this simulator, by design,
represents the "average person,"
and no one person is average, especially not you.
As an LTT viewer, you're decidedly above average.
So what that means is that the response curves
that we get from this head
will not directly reflect
what you hear in your ears.
It's just that by adding some objective knowledge
to your toolkit,
you can become a more informed consumer,
who can find the best headphones
for your needs faster.
Also, at our lab, the goal is
to never be satisfied with "good enough."
We're gonna spare no expense.
I mean, really, if I'm not putting my money
where my mouth is at this point,
come on guys,
but there is always going to be room for improvement.
We know that our tests weren't perfect here
for many reasons,
and no one is more critical about our testing protocols
than the very people that we've hired to create them,
but our lab is still under construction,
and achieving our goal of industry-leading testing is
going to take some time.
There's also just much more
that we'd love to test
outside of just the frequency response of headphones,
like the microphone's noise canceling, distortion testing,
even trying to find ways
to apply response curve data
to the human perceptual system.
So if there are tests you guys would like to see,
let us know in the comments,
because this is just the beginning,
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- Thanks for watching.
If you're interested in more headphone content,
check out our video, where we did some subjective testing
of $35 knockoff AirPods.
Spoiler, our staff, by and large,
actually preferred them to the real thing.