It’s nice sometimes to block out the sound of the outside world — like, all of it — but with fancy gadgetry often comes a steep price tag, and so it goes with nice headphones. $200, $300 or more? Come on — what’s so wrong with those bright white earbuds that came free with your phone? There are a million headphones out there — what’s the real difference in headphone quality all about, anyway?
Alongside USC electrical and computer engineering professor Chris Kyriakakis — who researches audio technologies and psychoacoustics (which looks at the way humans perceive sound), and who has tested more than 500 headphones in his lab, as well as consulting for the audio industry — we dialed up the volume on some answers.
Before we get into why noise-canceling headphones are so expensive, how do they actually cancel noise in the first place?
It’s nothing short of amazing. As Kyriakakis explains, in order to cancel noise, you have to know what noise is reaching the ear. This is done by putting one or more microphones on each headphone that listens to outside noise. Then that information is passed on to a processor that tells the speaker inside the headphone to produce an additional signal: Basically, it’s the exact opposite waveform of the sound you want to block, played at the exact same time. If it’s done right, the sound you don’t want to hear is imperceptible.
Whoa. How is that even a thing?
It’s anything but simple! Some microphones are outside, which makes sense, since noises are coming from outside the headphone. But every time someone puts on headphones, Kyriakakis says, the audio quality changes slightly because of the way it’s coupled to your ear. Meaning, the external microphone has been calibrated for one particular way of wearing the headphone, and if that’s not exactly right, some noise-canceling mismatches can affect the sound quality of what you’re trying to listen to.
So another way is putting microphones inside the headphone, to better pick up what things actually sound like once inside the ear cup (since most over-ear headphones will have some degree of sound-proofing that naturally blocks out higher frequency noises, like wind, or hissing). This requires more advanced processing. Yet another method is to have microphones on both the inside and outside that work together in a hybrid way, which tends to be the most advanced at the moment.
So you can cancel noise with noise?
It’s amazing, right? The microphones listen for a certain sound, then instantaneously mimic the sound with the exact negative waveform. The result, if done correctly, is a constant zero-sum game.
Why can’t we use this technology to cancel noise pretty much everywhere? Like, something that blocks out my endlessly yapping downstairs neighbors?
It gets pretty difficult if you’re not wearing headphones, and the reason is because of the timing. Take an airplane: Kyriakakis says you could tune speakers for one seat and make everything correct, but what about the seat next to it, which is a different distance from the sound’s origin? That’s where it gets tricky. The solution would probably, theoretically, involve little speakers in every headrest.
Kyriakakis says it’s been attempted in cars (where the driver’s position, or rather, the driver’s ear position, is pretty certain) but with mixed results. This is all next-generation stuff for now.
Noise-canceling headphones are basically adding more noise overall though, right?
Yes — if the outside noise magically stopped, and there was a lag, Kyriakakis says, you’d be bombarded with that opposite-phase noise. Thankfully, that’s designed not to happen!
I’m guessing all that noise-canceling tech adds to the cost of headphones.
Oh yeah, the added cost is real. There are the microphones, which Kyriakakis says cost tens of cents, but translates to dollars in cost to the consumer. Then there’s the chip (often licensed from a third party) and the circuitry that does the decision-making about canceling noise and making the opposite-waveform noise. That’s just the hardware — there’s also the software that actually makes all this happen. That can either be licensed from somebody or developed in house. It’s definitely more costly to build than headphones without noise cancelation, says Kyriakakis.
Another element of the higher price is the fact that noise canceling is a commodity by now, which is to say it’s an in-demand feature that people expect to pay more for. The feature self-evidently justifies the higher cost, in other words. That’s important to be aware of, because just as not all noise-canceling headphones are made equal, nor do they perform equally, according to Kyriakakis.
Aside from the particular process they choose to use (some are better than others), one reason is the explosion in headphone brands. That in turn is due to the growth of original design manufacturing (ODM) in China, in which most brands that aren’t major electronics players fly to China and go to a third-party headphone factory, wherein they’re shown a line of models for the year. The brand can then select colors and choose from the different technology packages, and then their brand of headphones is mass-produced. All they have to do is choose which celebrity they want to endorse it.
The reason for all this is that we’ve kind of solved headphones, if you think about it: We’ve made them wireless, we’ve canceled noise, you can make phone calls with them, and we’ve made them sound pretty good. They’re at the point where these features are at least somewhat replicable by ODMs.
On an ODM’s shopping list, noise canceling is a common option because these manufacturers don’t want brands shopping around. But “an R&D department at a manufacturing plant is likely to not have the same sophistication as an R&D department in an audio company that has decades of experience,” Kyriakakis says. “So you can imagine you get cookie-cutter versus innovative.”
How much of a difference is there?
Kyriakakis says you can judge it in two ways: One is the amount of noise and the frequency range of noise: “It’s much easier to do a good job at the lower frequencies, but if you try to get further up, it gets more challenging,” he explains. “Then the other way is, how much are you changing the music at the cost of cutting noise? The sophistication of those algorithms varies greatly.” Which is to say, some brands cancel noise better than others.
What’s the difference overall between expensive and cheap headphones?
Usually the most expensive parts of a headphone, in order, are the speakers themselves, including the drivers, transducers, magnets, even what the diaphragm of the speaker is made of (which affects both cost and performance); then there’s the microchip, which is often licensed — it’s the thing that handles all the noise-cancelation audio processing, plus Bluetooth, Wi-Fi, telephony and any other feature; and finally there’s the cosmetics (leather, metal, plastic, etc.).
(This is a good time to point out that headphones without noise cancelation can sound better than noise-canceling headphones at the same price, as that money instead goes toward better components. Though Kyriakakis questions why anyone would opt for a headphone instead of loudspeakers if you don’t need to cancel ambient noise.)
Anyway, it follows that cheaper headphones are going to naturally cut corners in materials and construction, and you’re likely not going to get features like Bluetooth or noise cancelation.
Does cutting corners really make a difference in sound?
It can, according to Kyriakakis. Cheaper speaker materials degrade the sound, while the plastics used will tend to vibrate more than on expensive headphones, which also degrades the sound.
Kyriakakis does a lot of consulting for major brands, so he declines to get into this much. But he claims that their quality has gone way up since Apple purchased the company. So… maybe believe the hype either way as much as you want.
Do expensive headphones really sound better, overall?
Generally, but not always! There’s a final piece to audio quality that some brands get right and others don’t: It’s to do with your ear canal, which is basically a straw-like tube that sits in front of your eardrum. It has its own resonances, and since headphones don’t bounce sound around the room like a loudspeaker — they go straight down your ear hole — headphone makers need to take into account this natural resonance, so that the music or whatever you’re listening to sounds unaltered by the time it reaches your eardrum. Knowing how to pre-undo, or “cancel” resonance using good design isn’t easy.
“The people who know how to do that really well make better headphones, and those that don’t, don’t,” Kyriakakis says. “But the thing we found was that cost isn’t always an indicator of that!” To this day in his lab there’s an internal joke about a pair of $14.99 plastic headphones that were so amazing that Kyriakakis and his team thought their measurement system was broken — they performed as if they were designed by a computer matching human perception, he says. He can’t say which model or brand it is, so don’t ask! But the same company’s more expensive offerings weren’t nearly as good. He still doesn’t know if it was just a total fluke, or if the engineer for that model was some kind of secret genius.
So expensive noise-canceling headphones aren’t always worth it?
Kyriakakis’s $14.99 example demonstrates there are exceptions. The problem is that headphones are hard to comparison-shop for these days based on sound quality — it’s impossible if you’re buying over the internet, unless you’re willing to order and then return a lot of products. It doesn’t help that online product reviews are about as trustworthy as political posts on Facebook. Overall, though, higher price usually equals better components, along with features like noise cancelation. What they do is truly amazing! But yeah, you’ll more than likely have to pay for it.