Saturday, 27 December 2014

wind protection

Firstly, its worth stating that the sound of wind in environments is not a problem - in fact getting a good recording of the sound of wind is quite something and is very effective in reflecting a sense of place. However the sound, known to all field recordists, often referred to as ‘buffering’ can be a problem. What we’re hearing is in fact the sound of wind hitting something - the microphone element for example. The effect is to push other sound to the back, cause a low frequency rumble and disrupt the listening potential of your recording.

tip # 1: if its very light, occasional and ‘fits’ in with the feel of the piece / recording it is much better to leave it in than to attempt any removal in editing, which is highly likely to alter all the other sound as well. This is why finding ways to protect your microphones from wind impact in the field is a very good idea indeed.

tip # 2: when you’re listening back to your recordings, as ever, listen back at a realistic volume. Often folks think a recording has been ruined by wind noise because they’ve been listening back to it at high volume - turn the volume down and a lot of light wind sound can fade into the background. Of course this doesn’t work if the wind has impacted on the capsule.

so, what are the ‘in the field’ options ? well, it depends somewhat on the microphones you’re using but with conventional microphones basically there are four techniques:

1) the most important: position ! changing the position of the microphones can radically reduce wind impact + it has the additional benefit of more of less forcing you to think creatively and to work with what you have (an essential element of field craft)

2) blimps: these are the elongated, zeppelin shaped devices that are common place with recordists. There are also ‘ball gag’ style blimps, circular in shape and suitable for single microphones or close stereo / surround arrays. Blimps consist of an inner cage (made from various types of plastic) with a handle and suspension mounts for the microphone/s + an acoustic mesh connected to the cage itself. In addition they are most usually seen covered in a removable fluffy cover.

a selection of Rycote Blimps: left to right: baby ball, blimp with hi-wind cover, super softie, standard blimp, short standard blimp, cyclone design blimp

tip # 3: fluffy covers are hardly ever actually needed - except in very strong winds. Even the most expensive and well designed fluffy covers do have a slight effect on the sound, reducing some of the high frequencies. What is a good idea and much better is to get what is called a ‘hi-wind cover’ - a flat fabric cover that is acoustically transparent but acts to slow down the wind velocity. If you have a blimp with a fluffy cover do remember there's no point at all leaving the cover on when recording indoors.

The purpose of a blimp is to create a space between the cage and the microphone and its this space that is important. Blimps don’t stop wind - they slow it down to a velocity which doesn’t register as that buffering noise through the microphone capsule. The bigger the space the better the effect. There are various companies selling these but perhaps the best two to focus on are Rycote (high quality) and Rode (one design and reasonably priced, decent quality). Prices for blimps range from a couple or hundred £'s (Rode and some Rycote designs) to £6-800 + (other Rycote designs, Cinela etc). As well as the wind reduction function of blimps, as mentioned, they also have suspension mounts for microphones which reduce noise from vibration. 

3) individual microphone fluffy’s: these small pieces of the fluffy material are designed to fit over the actual microphones (separate mics or those built in to hand held recorders). 

BubbleBee Industries BBi windjammers in various sizes

tip # 4: professional fluffy’s aren't made from fake fur or polar fleece material as those fabrics will effect the sound of your recordings more than acoustically transparent material. 

For small, omni microphones (such as the DPA4060 or Sanken COS-11) Rycote and BubbleBee Industries (BBi) make some of the best ones and Rode also make a decent fake fur one. The BBi’s have the double advantages of having a small ‘bubble’ built in, therefore creating a small air gap between the mic and the fabric + the have a tight, elasticated draw string design that holds them firmly in place. The Rycotes are a bit cheaper but they do tend to fall off fairly easily and when you’re in the middle of a forest or out at night losing a small fluffy cover is not good !

For handheld recorders there are lots of companies selling fluffy’s online that fit over the on-board mics but those by Rycote and Rode are two widely available manufacturers that use high quality fabrics (Rycote use acoustically transparent, Rode us a high quality fake fur style fabric).  As mentioned earlier, using fake fur ones will muffle the sound of the mics. If you’re fairly new to field recording you might not even notice the effect, but once your ears have grown more accustomed to close, focused listening it will become more and more apparent.

Some hand held recorders and microphones are also supplied with a foam cover. As lots of you will know these aren't intended as full  wind protection covers - they’re what is known as ‘pop shields’ designed to lessen the effect of certain vocal sounds during spoken word / song recording. That said, if you don’t have anything else to hand they can provide some slight reduction of wind noise. 

the DIY option: it is possible to build ones own wind protection cages / boxes and these are especially good for situation where the microphones will be left static (as they won't have high grade suspension mounts). There are various methods online but the quality is mostly, shall we say, a bit iffy - mostly because they contain the fake fur or lycra style fabric suggestions for what to cover the basic cage in. It's much better to use the speaker grill fabric from a pair of really old junk shop speakers (1970-80's or earlier) or track down the material used for hi-wind covers (which has various names in different countries).

I should qualify all this though by saying that using whatever you have to hand to construct or improvise some protection for your mics is still worth doing - its just good to be aware of the fact that it will have an impact on the sound. For years I couldn't afford high-end blimps so would use various fabrics when needed - I even remember using a walking glove once to capture a sound I stumbled across while out for a walk - the recording still stands as a memory of that discovery, which for me is an important element.

4) low cut filter:  a ‘low pass filter’ (also sometimes referred to as a High Pass Filter) will reduce some of the low frequency range and therefore can help remove wind noise and traffic rumble. Most recorders have an LPF menu where you can select different levels of filtration. If you do need to use your LPF then start with it on the first setting and only increase it if it doesn’t solve the issue. However, do remember that LPF’s are also removing frequencies that you might also want and they don’t just focus in on the ones you don’t. The balance therefore is always in asking what you’re losing by using them. Cheaper, hand held recorders will have fairly unsophisticated LPF's with just one or two, quite full-on settings. Professional recorders tend to have lots of different levels of LPF, allowing a more subtle filtering process. Personally I hardly ever use them anyway and much prefer to use position and other techniques to counter any wind noise. Likewise, when it comes to traffic rumble whilst it can be annoying at times, i’m of the opinion that that sound is part of the reality and by adjusting ones reaction to it, ones listening, its possible to hear it as part of the soundscape.

You can also apply low-pass filters in post production via whichever editing software you use. Again, if all you’re trying to do is remove some unwanted rumble then be very careful with the LPF. 

tip # 5: there’s a vast array of editing software programmes available - from freeware ones such as Audacity to top of the line, expensive suites like Nuendo. Lots of recordists will already have suites they’ve been using for years, perhaps having also used them for music editing applications, however for those who don’t or indeed those looking to try something else, there is one that I strongly suggest you take a look at: Reaper. This is a professionally maintained, fully functioned editing suite capable of everything that any other suite can do and indeed much more than many. Its also free to download and review (fully functioned) and a license for continued use is only $60 (they’re a US based company). Its used by leading recordists, Universities and other organisations. As with any editing suite there’s a bit of learning curve when you begin using it but most folks can be fully set up and using it within a few hours. It comes with a whole bank of plug-in’s (effects such as eq, high and low pass, reverb etc etc) and is compatible with additional plug-in’s for field recording such as the Schoeps m/s decoder.

Both in the field and in editing its often much better to leave in light / moderate wind noise / rumble and choose a good playback level than to remove it and also alter the overall frequency range of a recording. Of course this does depend on what you want to do with your recordings, but if its some representation of a ‘reality’ that you’re after then editing / eq-ing could easily affect that. The technology is there for all to use - it can be free or cheap and its fast to begin using - but, as with any creative process it takes time to understand the subtleties and, just as importantly, to find ways to use technology to express more than mere technical skill.  

There’s an increasing interest in all aspects of listening - how we hear, what we hear and how we either engage with or disconnect from sound - when it comes to presenting field recordings in various contexts (installation, release etc) its still often one aspect that is overlooked in favour of approaches that are actually more to do with music performance; volume, impact, effect, adrenalin, relaxation etc. Of course ones approach is personal but, in my opinion, thinking about these things is elemental.

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