100 Things #57: Measuring Headphone Active Noise Cancellation in Real Time

Active Noise Cancellation technology is more advanced than ever, and SoundCheck is well-equipped with all the features needed for measuring headphone active noise cancellation. We have a pre-written test sequence to measure all aspects of noise cancellation including passive, active, and total noise attenuation. This sequence is a great fully complete test, or you can use it as a template to expand your test setup to include multiple background noise sources, or add an additional microphone for an even more detailed test of how the ANC circuit responds to dynamic signals.

Measuring Headphone Active Noise Cancellation in Real Time

Try ANC headphone measurements for yourself

Find our free sequence for measuring Noise-Cancelling Headphones here. This sequence first measures the passive attenuation of the headphones, then the active attenuation, and finally calculates the total attenuation.

Video Script:

Did you know you can measure headphone Active Noise Cancellation with SoundCheck, as well as standard acoustic tests such as frequency response and distortion? When measuring noise canceling headphones there are three important measurements to make: passive attenuation, active attenuation, and total attenuation. Passive Attenuation is the amount of noise the headphones block without ANC enabled. Active Attenuation is the amount of noise ANC blocks out. Total Attenuation is the combination of the two measurements.

We even have a pre-written sequence showing off this functionality, called Noise Canceling Headphones, available on our website. You will need a Head and Torso Simulator (HATS) or an acoustic ear simulator with an artificial pinna, at least one speaker for background noise generation, and a set of headphones with ANC.

The first measurement is taken without headphones on the HATS, the unoccluded measurement. The pink noise stimulus is played out of the speakers, and the signal from the HATS is recorded. Next, the sequence pauses while the operator places the headphones on the HATS, then makes the occluded measurement. The sequence again pauses for the operator to enable the headphone’s active noise cancellation, and The third measurement is taken, and the results are calculated.

This test can be modified to work with a diffuse, multi-speaker configuration, and in an environment with two or more speakers, both ears could be measured at the same time. Our new AmpConnect 621 interface has six inputs, and two outputs so you can even measure both the left and right channel simultaneously, while also generating stereo background noise. Using SoundCheck’s new Multichannel RTA, you can measure the acoustic seal  of both the left and right headphone channels simultaneously, and even visualize it in real time. Also, with the Multi-RTA and an external reference measurement microphone positioned immediately next to the outside of the headphone, you can play any complex signal you like out of the source speaker(s) such as real recorded background noise from an airplane and watch in real time how the noise attenuation changes. This is a more realistic representation of how the ANC circuit responds to dynamic signals.  

There are many ways you can modify this sequence, for example, instead of playing out of one source speaker, play out of multiple equalized source speakers to create a more realistic spatial background noise environment. With the new Signal generator’s delay offset feature, this is much easier to do.

How do you measure active noise cancellation? And what are your favorite noise-canceling headphones? Let us know in the comments below! And for more information on all things SoundCheck, head to our website at ListenInc.com.