Wind noise reduction in Bluetooth mono headsets: How it works.

by Wind noise reduction in Bluetooth mono headsets: How it works. Daniel Gniazdo

Talking on a headset is rarely a problem when you’re outside on a calm, sunny day. But if you’re out in heavy wind, things get trickier. In most cases, people you talk to can barely hear you, or you end up sounding like a dying robot sending out an SOS.

Jabra Storm behind-the-ear Bluetooth headset

If you live in a windy city (not limited to Chicago) or use your headset on the road, you’ll come across this problem often. That’s why some Bluetooth mono headsets offer wind noise reduction. But what is this wind noise reduction all about and how does it happen?

First off, let’s be clear about what I mean by “wind noise reduction.” I’m not talking about you, the headset wearer, protecting yourself from wind noise. That tends to be difficult to achieve with a Bluetooth mono headset, on account of it covering just one of your ears. There are plenty of earmuffs and music headsets with a headband that can help you.

For our discussion here, “wind noise reduction” refers to helping the other person hear you clearly, instead of listening to the crunching noises from the wind. With that, let’s take a look at how it all works.

What causes microphone wind noise?

Bluetooth mono headsets rely on microphones to transmit your voice. Microphones are designed to pick up air vibrations, because that’s basically what your voice is. Guess what else is an air vibration? Yup: wind. When wind hits the microphone, it creates turbulence around it. This turbulence is pretty much what we call wind noise.

Now, microphones aren’t exactly smart. They treat all sound the same way, so they just end up sending the wind noise along with your voice. The other person gets all of these “good vibrations” directly in their ears, and everyone’s sad about the whole experience.

Headsets with wind noise reduction

Wind noise is an issue for most Bluetooth mono headsets. This is why some manufacturers introduce specialized headsets designed to deal with wind. Such headset combine several noise reduction elements to effectively counter wind noise. The difference they make can be quite impressive, actually. Have a look at this demo video:

As you can see, a Bluetooth mono headset with wind noise reduction can make your call sound much clearer than a smartphone. These headsets come in many different forms, but they all follow the same common principles to reduce wind noise. Such as…

Different layers of wind noise reduction

As we’ve seen above, there are two main factors that result in a person hearing wind noise:

  1. Wind generates turbulence around the headset microphone.
  2. Microphone captures and transmits both the wind noise and the voice.

To reduce wind noise, we have to either prevent turbulence from happening in the first place or make the headset better at distinguishing wind noise from voice. The first challenge is solved by the headset’s physical design. The second one is addressed by software.

Physical design: Reducing wind turbulence

Turbulence typically happens when wind gets caught in the headset’s sharp edges around the microphone. Designing these edges to be more rounded allows wind to pass over them smoothly, without creating as much turbulence. You can place tiny foam inserts directly above the microphone to filter out more wind noise. Headsets with wind noise reduction might also have a boom arm that extends closer to your mouth. This helps the microphone better pick up your voice.

Traditional microphones used by e.g. news reporters solve the issue in a more straightforward way: By surrounding the microphone with a thick layer of porous material. It can be artificial fur, cloth, foam, metal or plastic mesh. This material dissipates powerful gusts of wind while having little impact on speech. Sure, this method can seem a bit crude, but it’s also extremely effective.

Bluetooth mono headsets sometimes emulate this traditional method. They come with an optional “wind sock” made of foam that you can place directly over the boom arm when it’s especially windy outside.

Software: Separating noise from voice

While physical design tries to reduce turbulence in the first place, software solutions teach the headset to discriminate against wind noise. If you’re able to separate wind noise from speech, you can make sure that the headset only transmits your voice to the other side.

This is usually done with something called Digital Signal Processing (DSP). In the case of wind noise, DSP focuses on identifying features that make wind different from speech. For example, you can tell the software to treat all sound of a certain frequency as wind noise. The next step is to use the software to digitally subtract this “bad” sound from the rest of the transmitted signal. That’s also the basic idea behind regular noise cancellation.

If you really want to punch wind noise in its figurative face, you can combine the physical design and software. For example, having two microphones placed in different locations can help the software better tell wind noise from voice (and to more effectively suppress it). We’ve already talked about how dual noise-cancelling microphones work in this post.