Noise Masking or Active Noise Cancelling: Together or Alone?

Now let’s turn on the active noise cancelling function on these headphones (Sony WH-1000XM4):

The truck rumble is now almost gone and the barks of the larger dog are a lot quieter. Higher-pitched noises have come to the forefront.

But they are not really louder as we will see when we mask them (below). It is just that the lower frequencies in the street noise are so effectively reduced that they don’t mask the higher-pitched noises anymore.

(In case you are wondering how much quieter everything is, just play the original street and barking noise above again.)

It’s a world of a difference but the barking and honking aren’t gone yet.

Now let’s combine active noise cancelling and noise masking:

Both the barking and the street noise are gone. The only thing I can still hear is a faint honking towards the end (and only because I am looking for it).

In fact, if it wasn’t for the loud honking, we could have played the masking noise even at a substantially lower volume.

How much did active noise cancelling really help here?

That’s easy to hear.

For comparison, let’s turn off ANC and keep everything else the same, i.e., we rely on the headphones’ noise isolation and use the same masking noise volume as in the previous audio:

Now, some of the street noise, the barking in the background, and the lower-pitched horn can be heard again.

And to drive this point home, here is how much louder I had to play the masking noise to mask the barking and honking when we relied only passive noise reduction (and the result is still not as good):

In summary

• The headphones’ ANC function adds substantially to noise masking and passive noise isolation against both the street noise (mostly low frequencies), the lower-pitched barking (200 to 700 Hz) and large-vehicle honking (peaks at around 500 Hz).
• Even the higher-pitched barking is reduced: it exhibits a first peak at around 600 Hz, against which the ANC is effective.
  

Noise pollutants’ frequencies overview table

In the following table, I have identified some of the loudest “noise pollutants” in the noise sample you have just heard, and which of the applied tools contributed to reducing that noise:

Conclusion and current state of the art

Against many nighttime (and daytime) noises, noise masking, active noise cancelling, and passive noise isolation are synergistic.

This includes street noise, snoring, chatter, barking (larger dogs), honking, music bass, footstep noise, and HVAC systems.

Against higher-pitched crying, crickets, small dogs, and screeching brakes current active noise cancelling technology doesn’t offer much benefit. Good passive noise isolation in combination with an optimized masking noise are what counts.

If you can sleep on your back or need relief during the day, the combination of noise masking and quality over-ear active noise cancelling headphones (e.g., Sony WH-1000XM4) is a very effective tool against the “noisescape” you have just heard in this post.

A select few active noise cancelling earbuds also have a battery that lasts a whole night, but ideally they should be smaller to allow for comfortable side sleeping.

Specialized sleep earbuds with built-in masking sounds, such as Bose’s Sleepbuds, are available. They are very small, designed for side sleeping, and they have ear tips that sit at the ear canal entrance, so they don’t have to go in deep like foam earplugs.

But they and other current noise masking sleep earbuds don’t yet offer active noise cancellation.

This is somewhat surprising because Bose has great active noise cancelling technology in their normal earbuds. Perhaps they haven’t yet figured out how to make them small enough with a battery that can power both noise masking and noise cancelling for a whole night.

I have read the argument that noise cancellation is not effective against intermittent noises, but in my own experience, this is no longer the case with state-of-the-art noise cancelling headphones. Whether ANC helps or not depends much more on the dominant frequencies in the noise you want to eliminate.

Then there are other sleep earbuds, such as QuietOn, that do feature active noise cancelling but unfortunately no noise masking. As we have seen in this post, a customized masking sound is necessary if you want to make louder noises go away.

I don’t want to knock these devices, and, depending on the noise problem that needs solving, they can work just fine.

But, these sleep earbuds would be more powerful and versatile if, in addition to isolating well, they combined both active technologies used in this post:

I’d like to see small sleep earbuds with comfortable ear tips suitable for side sleepers that have customizable (via an EQ) built-in masking sounds and powerful active noise cancellation and an all-night battery.

I am optimistic, we will get there.