Unlock the Secret to Perfect Sound with These Simple Tips on Measuring Noise Canceling in Headphones!
If you’re a music lover or just someone who wants to enjoy the best sound quality while listening to audio, noise-canceling headphones are a must-have. But with so many different options available in the market, it can be overwhelming to pick the right one.
One of the most important factors to consider when buying noise-canceling headphones is the level of noise-canceling they provide. To measure this, you need to know the basics of noise-canceling technology and how to determine if the headphones you want to buy are effective.
Noise-Canceling Technology
Noise-canceling technology is designed to eliminate external sounds that may interfere with your audio experience. It works by capturing the external sound waves and producing an opposite sound wave that cancels it out. This is known as active noise canceling (ANC), which is especially useful in environments where there are many external sounds, such as in a busy office or on a plane.
There are also passive noise-canceling headphones that provide noise isolation by physically blocking external sounds. These types of headphones come with a more solid design to ensure all sounds stay out.
How to Test the Noise Canceling in Headphones
To measure noise canceling in headphones, you need to have a sound meter or a decibel meter app on your phone. Here are simple steps to take:
- First, put on the headphones and turn on the noise-canceling feature.
- Make sure you’re in a quiet environment and switch on your sound meter.
- Play a steady, loud tone or white noise through your headphones and measure the sound level with the sound meter.
- Turn off the noise-canceling feature and play the same tone or white noise again.
- Measure the sound level again.
The difference between the two readings is an indication of how effective the noise-canceling feature is. A two to three decibel (dB) drop in sound level is usually considered effective.
Other Factors to Consider
While testing the noise-canceling feature in headphones is important, it is not the only factor you should consider when buying a pair. Other factors such as comfort, sound quality, battery life, and price should also be considered when making a decision.
Overall, it is essential to know how to measure the effectiveness of noise-canceling in headphones to ensure you get the best listening experience possible. Knowing what features to look for and how to test them can help you pick the best headphones for your needs.
The efficacy of noise-canceling circuitry varies from headphone to headphone. A few are so effective you might think something’s wrong with your ears, while others only cancel a few decibels worth of noise. Even worse, some add audible hiss, so while they may reduce noise at low frequencies, they increase it at high frequencies.
Measuring noise-canceling functions in a pair of headphones involves generating pink noise through a set of speakers, then measuring how much sound gets through the headphone to your ears.
Set up the Gear
Measuring noise-canceling ability requires:
- Basic audio spectrum analyzer software, such as True RTA.A USB microphone interface, such as the Blue Icicle microphone.An ear/cheek simulator such as the G.R.A.S 43AG, or a headphone measurement mannequin such as the G.R.A.S. KEMAR.
You can see the basic setup in the above photo. That’s the 43AG in the lower-left corner, fitted with a rubber earpiece representing an earlobe typical of some people. Earpieces are available in a variety of sizes and different durometers.
Make Some Noise
Generating the test signals is a little more challenging if you go by the book. The IEC 60268-7 headphone measurement standard dictates that this test’s sound source should be eight speakers positioned in the corners of the room, each playing an uncorrelated noise source. Uncorrelated means that each speaker gets a random noise signal, so none of the signals is the same.
For this example, the setup involves two Genelec HT205 powered speakers in opposite corners of the test space, each one firing into the corner to disperse its sound better. The two speakers receive uncorrelated noise signals. A Sunfire TS-SJ8 subwoofer in one corner adds some bass.
You can see the setup in the diagram above. The small squares firing into the corners are the Genelecs, the large rectangle in the lower-right corner is the Sunfire sub, and the brown rectangle is the test bench where the measurements are done.
Run the Measurement
To begin the measurement, get the noise playing, then set the noise level to measure 75 dB near the entrance to the 43AG’s fake rubber ear canal, measured using a standard sound pressure level (SPL) meter. To get a baseline of what the sound is outside the artificial ear, so you can use that as a reference, click the REF key in TrueRTA. This key gives the flat line on the graph at 75 dB. (You can see this in the below image.)
Next, place the headphone on the ear/cheek simulator. Fit the bottom of the test bench with woodblocks, so the distance from the top plate of the 43AG to the bottom of the woodblocks is the same as the head’s dimensions at the ears. (It’s about 7 inches.) This setup maintains the appropriate pressure of the headphone against the ear/cheek simulator.
Per IEC 60268-7, set TrueRTA for 1/3-octave smoothing and set it to average 12 different samples. Still, like any measurement involving noise, it’s impossible to get it 100 percent precise because noise is random.
Confirm the Result
The chart below shows the result of a measurement of the Phiaton Chord MC 530 noise-canceling headphone. The cyan line is the baseline—what the ear/cheek simulator hears when there’s no headphone there. The green line is the result with noise-canceling switched off. The purple line is the result with noise-canceling switched on.
The noise-canceling circuitry has its most potent effect between 70 Hz and 500 Hz, which is typical. It’s a good thing because that’s the band in which the droning engine noise inside an airliner cabin resides. The noise-canceling circuitry can increase the noise level at high frequencies, as seen in this chart where the noise is higher between 1 kHz and 2.5 kHz with noise-canceling on.
But the test isn’t finished until it’s confirmed by ear. To do this, we used our stereo system to play a recording we made of sound inside an airline cabin. We made our recording in one of the rear seats of an MD-80 jet, one of the oldest and noisiest types currently in commercial service in the U.S.
Like every audio measurement, this one’s not perfect. Although the subwoofer is placed as far away as possible from the test bench, the test bench is on felt feet. The ear/cheek simulator has compliant rubber feet; at least some bass vibration sneaks directly into the microphone through physical conduction.
Did You Know?
Inside a plane’s cockpit, noise levels can reach up to 85 Db. Pilots use aviation headsets to reduce the impact on their eardrums. Consumers can now buy aviation headphones, too, so if you are experiencing high noise levels and regular headsets aren’t getting the job done then look into aviation headsets. They just might fit the bill for you.
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