Brian Fligor, an audiologist who is a member of the World Health Organization’s working group on safe listening devices, advised the team on how to compare its results to data on the 85-decibel workplace limit. (Headphones and earbuds are much closer to the ear, obviously; the workplace limit was devised with open areas in mind.) 
 
 Lauren Dragan, an editor at The Wirecutter, also corralled a half-dozen children, 3 to 11 years old, to try on each model, choose favorites and compile a “hate list” of ones they would never use. 
 
 In the end, the overall pick for the children was a Bluetooth model called the Puro BT2200 ($99.99). The headphones were well-liked by both toddlers and tweens, had excellent sound quality, offered some noise cancellation features and adequately restricted volume as long as the cord wasn’t used. 
 
 The battery lasts an impressive 18 to 22 hours, and the wired connection is used only as a backup. But that cord must be plugged in as labeled, with one particular end to the headphones and the other to the music device. If inserted the wrong way, “it’ll play really loud,” said Brent Butterworth, an audio expert who helped test all the headphones. 
 
 “If they are using it in Bluetooth mode, it’s impossible to make too loud,” he added. 
 
 Most of the other models relied on resistors, which impede electrical currents, inside the cord to reduce volume, but they sometimes failed to work. Both of the overall runners-up were not Bluetooth, however; despite the cords, their maximum volumes did not exceed 85 decibels. 
 
 Toddlers liked the fit of Onanoff Buddyphones Explore ($29.99) but will most likely outgrow them, the analysis found, and the sound quality didn’t compare to that of the Puro. The corded pick for older children, ages 4 to 11, was JLab JBuddies Studio ($29.99). 
 
 The Wirecutter team also assessed the headphones’ ability to reduce ambient noise. Children often wear headphones in noisy places, like car back seats and planes. Without noise cancellation, the natural tendency is to pump up the volume to hear over the background noise. ||||| Transcript for Report Reveals Kids' Headphones May Cause Hearing Problems 
 
 And we're back now with that alert about headphones a brand new report out this morning is raising big questions could some potentially hurt your children's hearing. ABC's nick watt has more. Yes indeed but are some heads but eventually parroting. Some of our testing they got as loud as a chainsaw or a check hammer. The study suggests one in five teens now suffers some hearing loss and some doctors. Blame that fans for seeing kids as young as seven. Who've had. Noise induced hearing loss they are listening to her headphones that. Full blast you're really talking about listen to a rock concert on a daily basis. The wire cut their tech guide just tested their tickets had phones style fits and safety using plastic here and some real life children. Their flat feet if this they're squishy. Basically she its report this morning. There's no governing board that oversees a staff she says these headphones old Clayton to limit the volume to around 85 decibels lad as the fled there. Safe according to the World Health Organization. Once considered the best are the Caro BT 2200 free to fail safe limit their basic six and change. But choir concert claims other models went over the 85 DB. During their tests had friends that received a poorest rating kid's gear wired headphones yup. My kids to use them and the vinyl and hitting hard on knees it's Ari gone prisoners come pick it's off. Went to limit their wire cuts reclaimed the audio level it's fine way to act was glad his 110. Decibels but still out. Farms it's geared told us in over fifteen years we've never had a customer complaints on using your limits are when needed when volume limit to his youth stakes and is achieved any issue it volume. Is a user. Configuration issue aren't present Justin humor. Please Good Morning America and it bought ABC news. Save us. No wire cutter does get a percentage of money from retailers for products sold through their links in their articles and it's important to note is up to adults to monitor child's overall noise exposure. Headphones are on my kids Christmas as every year really I never checks. I will now. They haven't guitar right. 
 
 This transcript has been automatically generated and may not be 100% accurate. ||||| The human ear and brain can’t accurately assess the volume of sound; if they could, there might be no need for volume-limiting headphones. So in order to test how loud the kids headphones could play, we did a set of formal objective sound measurements using audio-testing equipment. 
 
 Immediately we found a problem: Almost all these headphones can produce dangerously high volume if you use them with certain gear. And not just specialized gear—a relatively high-powered headphone amplifier, such as the ones built into many AV receivers, or the stand-alone amps popular among enthusiasts (and for most traditional lab measurements), could drive most any headphones well above 85 dB. 
 
 This problem happens because most of these headphones don’t really limit volume but merely reduce it. Passive headphones (that is, non-powered headphones, the kind you’re probably most familiar with) reduce volume using resistors, an inexpensive electrical component that reduces electrical flow. The technique is similar to splicing a narrow piece of water pipe onto the end of a fatter pipe, which reduces the amount of water coming through the pipe. However, you can get the overall flow of water back up to the original level by increasing the pressure going through the pipe. In the case of headphones, you apply the extra “pressure” by turning up the volume on the source device. Sure, the headphones are reducing the volume as if you had the dial on 5 instead of 8, but if you turn the volume to 11 it’ll still sound like it’s on 8. 
 
 Active headphones (in other words, internally powered ones) such as the Puro BT2200 can employ a digital limiter that stops the sound from playing any higher than a certain volume level. But few of the headphones we tested for this guide have internal amplifiers or digital processors, so they’re not precise. In our tests, a few of the passive models produced little, if any, reduction or limiting of volume. 
 
 Of course, a child will almost certainly use a phone, tablet, or portable music player for most or all of their listening, so the fact that most of these headphones will play much louder with a headphone amp is largely irrelevant in day-to-day use. However, we did need to settle on an appropriate source for the audio signals we would be using in our tests. Jason Wehner, an engineering consultant who has been involved in the design of volume-limiting headphones, made the sensible suggestion of using an iPhone as our source device, because iPhones are the loudest source most people will encounter—the iPhone’s internal amplifiers are more powerful than those found in most Android phones. We ended up using an iPod touch (sixth-generation model), which was able to play slightly louder (+0.38 dB) than our iPhone 6s and substantially louder (+4.4 dB) than our Samsung Galaxy S6. The iPod touch is popular as a “starter screen” for young children, so it seemed an appropriate choice here. We haven’t, however, exhaustively tested the output of all possible sources—video game consoles and home theater receivers, for example—so we’re unclear on how these headphones would perform with them. In any case, such devices would likely be used by older kids with gaming headsets, which don’t make any volume-limiting claims and are somewhat outside the scope of this guide (though parents and caregivers should be aware). 
 
 The hearing experts we consulted suggested using pink noise, a common test signal with an equal amount of energy per octave that more or less mimics the content of music. To the ear, pink noise sounds a lot like the white noise you’d hear between stations with an old analog-tuner FM radio, but less hissy sounding. We used pink noise with A-weighting, which basically removes frequencies below about 500 Hz (about an octave above middle C on a piano). According to Brian Fligor, chair of the WHO’s Make Listening Safe initiative and one of the experts we interviewed and consulted, low frequencies have a negligible effect on hearing loss. 
 
 As we’ve already discussed, the general consensus among experts is that an environmental noise level of 85 dBA (the “A” standing for A-weighting) is considered reasonably safe for an hour of listening. (For the technically inclined, the pink noise we used for these tests has an average level of -10 dBFS, or decibels relative to full scale, which is what audio manufacturers often use to measure the maximum volume of their devices.) 
 
 Although pink noise loosely simulates the content of music, it’s still just a simulation, one that serves to make measurements easier and more repeatable. We wanted to add a more real-world evaluation of how loud these headphones could get. To do that, we played a recent Top 40 hit, “Cold Water” by Major Lazer, through all the headphones and measured the A-weighted L eq (equivalent continuous sound level). L eq is a commonly used gauge of sound exposure over time; to oversimplify a bit, it’s sort of like the average volume. 
 
 We used the first chorus (from 0:45 to 1:06), which is one of the louder parts of “Cold Water” and roughly analogous to loud dance music. This was something of a worst-case test, because our L eq measurement of the entire tune was typically -1.3 dB lower, although we could have listened at an even louder level for this test because the second chorus typically measured +1.5 dB louder than the first. We also ran test measurements using another tune, ZZ Top’s “Chartreuse.” This track is a very loud recording that’s heavily dynamically compressed, which means the average sound level is pretty close to the maximum sound level possible, resulting in a track that to the ear sounds louder overall. The results were similar to what we measured from the first chorus of “Cold Water.” 
 
 For all of these measurements, we attached the headphones to a G.R.A.S. 43AG ear/cheek simulator. At the suggestions of the hearing experts we consulted, we used what’s referred to as a “diffuse-field calibration curve.” We did so because hearing researchers originally determined the theoretically safer environmental sound levels (the 85 dBA amount) using a sound pressure level meter held in free air without much around it. Sound that reaches the eardrum—and sound that reaches the measurement microphone built into the G.R.A.S. 43AG—is altered by the earlobe and ear canal (or in the case of the 43AG, by the simulated rubber earlobe and metal ear canal). So to make sure our measurements were comparable to that 85 dBA free-air measurement, we had to create a method to electronically reverse the way the 43AG’s simulated earlobe and ear canal change the sound. The correction curve (think of this as similar to an EQ adjustment) we created was the “diffuse-field calibration curve.” We created this curve by playing pink noise through a speaker, measuring that noise with an Audiomatica MIC-01 measurement microphone and CLIO 10 FW analyzer, and then comparing that measurement with one taken using the G.R.A.S. 43AG in the same location. Thus, using this correction curve, the levels we measured through the ear/cheek simulator would be directly comparable with environmental-noise measurements. 
 
 We calibrated the 43AG’s level using a Reed SC-05 calibrator. For the A-weighted pink noise and L eq measurements, we connected the 43AG to an M-Audio Mobile Pre USB interface and a laptop computer running Room EQ Wizard, a free but powerful audio-measurement application. (By the way, we employed roughly $8,000 worth of test gear in this effort.) 
 
 Note that headphone measurements have some inherent inconsistency. Small differences in the fit of the headphone on the ear/cheek simulator can affect the result, just as moving a headphone around slightly on your ear changes the sound. We did everything possible to ensure a good fit of each pair of headphones on the simulator, including using light pressure from the 43AG’s clamping mechanism to help seat the headphones on the simulated rubber earlobe, and listening to the signal coming from the 43AG’s internal microphone to confirm that the sound from each model being tested was coming through properly. Still, we needed to allow for possible measurement inaccuracy, so we decided to make 88 dBA our pass/fail point on the pink noise tests. Any set of headphones that doesn’t exceed that level with pink noise can be considered reasonably safe, along the guidelines explained in this review. Any set of headphones that exceeds this threshold by a few decibels isn’t necessarily dangerous but is less safe than models that pass the test. 
 
 As Brian Fligor pointed out to us, “Most all earphones [headphones] could be used in an unsafe manner. If the max sound level is so low that it can’t get over the background noise of an airplane or minivan on a highway, then it’s not going to sound very good. To make music sound good, the max level does need to have some headroom. This is where a combination of safer level limits along with earphones that block out competing background noise is probably the safest combination.” 
 
 To find out which kids headphone models performed well in this regard, we ran the same type of isolation measurements we use to test noise-cancelling headphones: We played pink noise through two speakers and a subwoofer at a level of 75 dB, placed each headphone model on the G.R.A.S. 43AG ear/cheek simulator, and then performed analysis using TrueRTA software to learn how much sound was leaking around or through the headphone into the 43AG’s microphone (and, by extension, into the wearer’s ears). 
 
 Unfortunately, only four of the headphones we tested provided notably effective isolation, blocking out a significant amount of sound in the audio spectrum (50 Hz to 2 kHz) that’s typically loudest in the backseat of a car, where we expect kids headphones might get a lot of use. And these pairs weren’t among the best performers in volume limiting, nor were they among our child test panel’s favorites. This group included the Direct Sound YourTones, which reduced sounds in this region by -8.1 dB, and the Fuhu Nabi Headphones, which reduced the same sounds by -4.8 dB. (Note that both of those pairs are large over-ear models.) The two in-ear models we tested did an even better job of blocking outside sounds. The Etymotic ETY-Kids3 reduced environmental noise by -22.0 dB in the test spectrum, and the Puro IEM200 reduced it by -14.4 dB. Note that these results are relevant only for situations where most of the noise is fairly low-frequency, such as in a car or an airplane cabin. Many of these headphones will do a better job of blocking common household noise such as the roar of a vacuum cleaner.
– If you're on the hunt for children's headphones—so-called because they limit the volume of sound that they emit to protect children's ears—experts are issuing a stern warning: They're not necessarily safe, even if they purport to be. The Wirecutter, a product recommendations site, has just tested 30 sets of children's headphones and found that half of them in fact do not cap volume at a promised limit, and that the worst of the bunch emit such high volumes that damage can occur in a matter of minutes. "These are terribly important findings," one pediatric audiologist not involved in the testing tells the New York Times. "Manufacturers are making claims that aren’t accurate." Meanwhile, the Wirecutter's headphones editor tells Good Morning America that there isn't even a governing board that oversees this. The World Health Organization has deemed sound below 85 decibels to be safe for up to eight hours, but half the headphones went above this level, and in some instances children can even remove the volume limiter. Meanwhile, one in five teens suffers from hearing loss, according to a 2010 report in the Journal of American Medical Association, and some docs blame headphones. "We’re really talking about listening to a rock concert on a daily basis," one otolaryngologist tells ABC News. So which headphone set came out on top? The Wirecutter recommends Puro BT2200, which are Bluetooth wireless headphones that'll set you back $100. (Back in 2008, researchers predicted an 'epidemic' of hearing loss thanks in part to headphones.)