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Rocket Science - the company that immobilises a fireplace
by Livia Gamper
Are they really twice as good? Audio geeks measure the ANC of AirPods Pro
26.9.2022
Translation: Jessica Johnson-Ferguson
Pictures: Christian Walker
Apple presents its new AirPods Pro and claims their active noise cancellation is «up to twice as good». Audio experts working for Zurich-based company Rocket Science got out their measuring devices to verify this statement.
«With up to double the noise-cancelling power of their predecessor, the world’s bestselling wireless headphones just got even better.» Apple writes in its press release announcing the new AirPods Pro. Of course, it wasn’t going to take long for Apple’s claim to be challenged. No sooner are the new second-generation AirPods Pro released than one set of earbuds is popped into a measuring device at Rocket Science.
«Twice as good doesn’t say much in acoustics without a clear context,» Luca Zimmermann of Rocket Science deadpans. «But let’s see what they deliver.»
Digitec sent the company one pair of the new and one of the old AirPods Pro. Both models were measured using the same measurement methodology.
Improved performance in the low frequencies
The red line in the chart shows the curve of the new AirPods Pro, i.e. the second-generation AirPods Pro. The blue curve shows those of the first generation AirPods Pro.
The curves reveal that the new version of the AirPods Pro offers significantly better noise cancelling, especially in the low frequencies. This confirms Apple’s claim that ANC is more efficient in the latest model. However, this only applies to the low frequencies from 50 Hz to about 125 Hz. In the range between 700 Hz and 2000 Hz, the old version of the AirPods is slightly better at cancelling noise. Luca didn’t want to make a statement as to why this is the case: «It could be down to anything.»
The new AirPods take the lead again in the high frequencies starting at around 2000 Hz to 8000 Hz. This range includes frequencies that play an important role in making speech easy to understand. In other words, voices and conversations are reduced more efficiently. This can come in really handy when we're working in the office or on our commute, where we're often distracted by the chatter of co-workers or fellow passengers.
By the way, in case you were wondering why the curves start above the zero line in the graph, the increase in low frequencies stems from the so-called overshoot of the noise cancelling filter. Filters involve trade-offs. This means that the reduction of certain frequency bands can lead to the increase of others. It seems that Apple decided to confine the increase in low frequencies to an area where most people aren’t bothered by it. However, there are users who feel an unpleasant pressure when they’re using noise-cancelling headphones. And it’s precisely this phenomenon that causes it.
Luca concludes that the noise reduction of the new generation is certainly better than that of the old one – at least when you look at the measurement results. As with almost everything, it depends on the circumstances or the ambient noise when you’re using them.
The measuring method
As we all know, don’t trust any statistic you didn’t fake yourself. That’s why the audio experts explain how they measured the AirPods Pro in the following: the measurement setup consisted of a speaker, a tube that simulates the ear canal for the AirPods Pro, two microphones A and B and a computer to record the measurement. The speakers played back Pink Noise.
Pink noise is often present in everyday life and covers a wide frequency spectrum. This makes it suitable for measurement. The AirPods Pro is inserted into one end of the artificial ear canal, while the other end of the tube is slipped over microphone A. Microphone A then hears the effect noise cancelling has on the pink noise emanating from the speaker. To isolate the effect of noise cancelling, the signal of microphone B, i.e. the pure noise signal, is subtracted from signal A. This value represents the difference between the signals – and therefore the efficiency of the active noise cancelling.
Verdict: new AirPods Pro more efficient, but not in all areas
It can be concluded that the new AirPods Pro do have improved ANC compared to the previous generation. Apple’s claim that the noise suppression is significantly more efficient is also true – but only within a certain frequency spectrum. What’s more, «twice as good» can mean something different depending on the decibel scale. And the scales are logarithmic, meaning they become steeper and steeper.
In other words, sweeping statements made by manufacturers on the efficiency of ANC should always be taken with a pinch of salt.
Testing devices and gadgets is my thing. Some experiments lead to interesting insights, others to demolished phones. I’m hooked on series and can’t imagine life without Netflix. In summer, you’ll find me soaking up the sun by the lake or at a music festival.
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