Reducing wind noise

I used to live in Edinburgh, a breezy city at the best of times. Once it was so windy that I could feel my second floor flat moving slightly – in a Victorian building made out of sandstone.

So I have a fair bit of experience of trying to make field and location recordings in high winds. For the uninitiated, wind on a microphone makes a rumbly farty distorting sound. Directional mics are especially bad for it. Here are some examples:

 

(I think what happens is that the wind creates very low frequency vibration in the mic diaphragm, infrasound, so that the mic is essentially sending a DC current into the preamps. This not only makes a lot of sub bass, hence the rumble, but also overloads the preamps, hence the distortion. I’m just guessing here though – could be wrong.)

Some people are more tolerant than me, and argue that a bit of wind noise can give a sense of weather and atmosphere.

But if wind is causing you trouble, here are some suggestions for how to reduce it.

The best solution is to avoid getting wind noise into your recordings in the first place. To achieve this you can:

1. Use appropriate wind protection. Foam windshields are not much good for outdoors unless there’s very little wind around. You need the furry things – you’ll have seen them on TV, shoved in front of the speaking face of a politician, or being knocked over by footballs when a goal is scored. Wimbledon even has special green coloured ones, presumably to blend in more with the grass or something.

Rycote make windshields in all shapes and sizes, for just about any decent mic or recorder you can think of. I’ve found the company very helpful – give them a call, tell them what you need and they’ll give you the options. Their basic wind jammers ones are cheap (from around £30) but less effective; the more sophisticated ones (with superstar names like ‘full modular suspension’, or the appallingly-titled ‘baby ball gag’ – yes, you read correctly) are more pricey, going up to around £400 depending on the options, but they are very effective, unless you’re in gale force conditions (like in the examples above) or doing something daft like pointing the mic directly into strong wind.

As far as I know, Rycote stuff is still made in the UK, which I think is worth supporting. Not due to some anti-foreign UKIP attitude, but rather to avoid shipping yet more stuff all the way from China that’s probably been made by people getting paid sod all for working long hours in shitty conditions. Rycote don’t pay me for saying this stuff, I just like their products and customer service.

Rycote gear
Rycote wind protection. Left: a low cost mini windjammer will provide modest wind noise reduction for portable recorders such as this Zoom H4n. Right: a more expensive full modular windshield provides much higher wind noise reduction. The little brush is for combing the hair.

2. If you’re on a tight budget consider Rode’s ‘dead cat’ and ‘dead kitten’ models (wind protection seems to bring out the manufacturers’ oddball humour), or try to borrow a wind protection kit from somewhere, or hire stuff – look for places that loan out broadcast sound gear, like this company in London or this company in Scotland.

Or there is the DIY approach. I’ve seen online tutorials about how to build your own windshield, and I once spent an entire weekend sourcing fake fur and disassembling several sieves, whose mesh I then heat-glued together with a reshaped wire coathanger to make a zeppelin style basket. The mic was held in place by elastic bands. I wish I had photos of that. The only fur I could find was luminous pink, so it looked like a tiny Elton John costume. Needless to say it wasn’t very effective. Soon afterwards I managed to find funds to buy the real deal from Rycote. The sieve/fur/coathanger/Elton John job got binned swiftly. Never looked back.

3. Buy a high wind cover for your Rycote. This is a fleece layer that sits between the basket and the fur, and it adds a few dB of wind noise reduction. See here for one example. It’s not too expensive, and I think it does work, enough to be worth using. Together with the fur it does reduce the high frequencies a bit, but a modest shelving boost in post (e.g. in your audio editing software), say 3dB from around 8kHz, will help with that.

4. Find shelter e.g. by angling your body into the wind and pointing the mics away, or looking for a structure that will act as a windbreak, or moving into the lee of a hill. I usually carry a rucsac with me, so I will dump that on the ground and put the mics in the lee of it to break up the air flow a bit.

5. Get low down. Wind shear means that wind velocity drops massively the lower to the ground you go, and increases as you go higher. Try putting your windshielded mic actually on the ground – it can help. I’ve also heard of acousticians measuring wind turbine noise by mounting miniature mics in wooden boards, with the mic flush to the surface. The boards are then placed on the ground with a windshield over the top. Never tried that myself though, so can’t comment on the results. You would get boundary effects, which will boost the levels, but might also mess with other aspects of the sound (on the few occasions I’ve tried boundary micing, I’ve never liked how it sounds).

6. Use omnidirectional mics. They are more resistant to wind than directional mics. DPA 4060 miniature mics are good for this. They still need some windshielding, but in any given windshield they will perform better than a directional mic. I find that the little lavalier windjammers that fit over these mics, like furballs, are OK for a light breeze, but for anything more I have to mount the DPAs in my full Rycote suspension. But then they work great, and the combo seems to be more wind resistant than when I have directional mics mounted in the windshield.

7. Consider using contact mics or hydrophones when recording in a windy place. Contact mics will sometimes pick up a bit of the air whistling past them, but otherwise they’re immune to wind noise. And hydrophones, being in the water, won’t be troubled by unruly air flows.

Contact mics
Contact mics transduce vibrations in solids rather than in air, so they don’t suffer from the same problems with wind noise as ordinary microphones.

8. Engage the high pass filter on your recorder. This will only be helpful if the filter is a hardware one located in the preamps. Peter Cusack once explained to me that often these filters are digital, and therefore at a point in the signal chain after any overloading of the preamps has already occurred. In that case you’re probably better off waiting until post-production and doing high pass/low cut filtering there so you have more control over the situation (see below).

In the Sound Devices 702 that I use, the first pole of filtering is analogue, 40Hz with a 6dB per octave slope, which can definitely help reduce the overloading of the preamps from very low frequencies.

9. Avoid recording in high winds. Stating the obvious, and sometimes not possible, but worth thinking about. Wait till it’s all blown over.

If all of the above fails and you do end up with wind noise in your recordings, provided it’s not too extreme there are several ways to reduce it:

  • Edit it out. If the noise is a problem for just a few occasional moments, you can cut out the relevant sections in your editing software and use equal power crossfades to join the bits either side back together again. This works particularly well where the recording is of a fairly continuous sound, so the crossfade isn’t noticeable.
  • Apply a high pass filter or low cut equalisation. You’ll need to play around with the frequency and slope. I suggest starting with about -6dB of shelving at around 100Hz, and then move the frequency around a bit to find the best spot.(If you’re having trouble deciding on the frequency, one trick is to start by boosting, say by +12dB or even more, and sweep around to find the frequency where the noise seems to jump out at you most. Then cut at that frequency.) It’s easy to overdo it though. If you cut too much bass from everything you can end up with very thin sounding results, so proceed with caution. It will work better where the other sounds are higher frequency, e.g. most bird song isn’t going to be affected by cutting low frequencies because it doesn’t contain any, whereas the drone of traffic contains lots of low end so will be more adversely affected.
  • Use automation to activate the filtering/EQ right at the moment when it’s needed, and then remove it afterwards. That way, the low end will be retained in the rest of the recording. In DAWs such as Logic audio you can automate the controls to achieve this. Set an EQ plugin on your channel. Turn automation  on. Again, start with a low shelf cut around 100Hz, maybe a bit higher; again play around and listen for what works best. Then find your spike of wind noise in the waveform, zoom in, and use the automation to adjust the amount of cut on the EQ. Use a curve starting just before the noise, ramping down to say -12dB, and then curving up again. The shorter the time you cut for, the more extreme cut you can get away with. Using a slight curve may be more subtle and less of an obvious edit than if you just switch the filter straight in and then out again.
  • Try a noise reduction program like Izotope RX. However, whilst I’ve found this to be superb when it comes to reducing most kinds of noise with the minimum of artefacts, the one time I tried to use it on wind noise it didn’t work well at all. It pulled out a lot of frequencies and in the end I just went for a conventional low cut. But maybe you can get it to work better than I did.

This ‘how to’ guide was produced as part of a research fellowship entitled ‘Researching sonic environments: exploring audio methodologies’. Thanks to the AHRC for funding this project.

6 Replies to “Reducing wind noise”

  1. Thanks for this. Just bought a Tascam and have started recording bird noises whilst still getting to know how to use the machine. My first problem I encountered was the picking up of a breeze I barely noticed! So I ordered a er, muff, and tried again today with a sock to see. Mainly it picked up me tinkering with the sock ha. Going to try out these suggestions; thanks for posting up something like this, I found it really helpful :)

  2. Hi Lucy, glad this was useful. Yes mics are more sensitive to wind than ears – using a mic outdoors without a windshield would be a bit like exposing your eardrum to the elements without the protection of the outer ear. A thin layer of fabric like a sock can help a bit, but really what you need is long fur to break up the air currents. Good luck with your recordings.

  3. Thank you very much for this Michael, a very good guide for someone like me (pretty much a beginner in sound recording land). I am thinking about getting either the Rode dead kitten or the Rycote mini windjammer for my Zoom H4n. Thing is, I also have a Rode Videomic Pro for recording with my DLSR and was wondering if these wind screens also fit on there. Hope you can help! Best, Thijs

  4. Dear Thijs, thanks, I’m not sure – I have an H4N and mini windjammer for that, but I don’t have a videomic pro to check if it fits. Have a look at the size and shape of the videomic – is it similar to the H4N? In photos it looks different – like the videomic would need a longer thinner windjammer. If in doubt, give Rode and Rycote a call.

  5. I hope you don’t mind me resurrecting the discussion but I’m looking for a way to remove noise from my camera video. The mics are on either side of the camera in tiny holes and so the resultant wind noise is extremely well separated in the stereo. In other words there’s no wind noise between the speakers or across the sound stage, it’s all hard left and hard right. So what I guess I need to do is keep anything that is present in BOTH channels to some degree and remove all audio that is 100% panned Left or Right. Is this possible? Kind of the opposite of removing a vocal from centre stage?

  6. Hmmm, interesting scenario. There might be some way using some sort of mid side processing; I’m afraid it’s beyond me to figure this out though. Let me know if you work it out!

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