Indoors, lavalier mics work just fine. But when used outdoors on location, only a slight amount of blowing air can cause havoc. The cheap, thin foam wind screens that come with many lavs are rarely enough to offer genuine wind protection.

Audio-Technica, a manufacturer of lavalier mics, did a white paper on how to prevent outdoor noise from destroying the audio. The company noted that when wind blows directly into the open sound ports of a tiny microphone — striking the diaphragm — it creates the objectionable noise.

Sadly, when this wind noise occurs, the problem is so severe it can’t be fixed in post. The noise must be completely edited out and replaced with another piece of audio. A strong gust of wind can easily ruin a one of a kind take. Many great interviews have been lost due to wind problems in the field.

The first rule, Audio-Technica said, is to be careful using the foam windscreen included with many lav mics. These might be OK on the outside of clothing in very light breezes, but should never be used on the inside of clothing. Moleskin or sticky triangles wrapped around a lavalier would most likely end up destroying that delicate piece of foam when the tape is removed.

In heavy windy conditions, don’t even try the foam windscreen, since it won’t work. Without a proper outdoor windscreen, Audio-Technica suggests a homemade method to make a windscreen from a cheap foam swab (not cotton) and other materials.

First, pull the foam tip off of the wooden handle, and then use a sharp knife to slice off the tapered bottom. (Remove the cotton stuffing if there is any.) Next, wrap a swaddling of porous cloth several times around the mic so that it begins to look like a Mummy’s thumb.

Cheesecloth, soft first-aid gauze, cut up T-shirts or even gun cleaning patches can be added. Finally, to cap everything in place and provide an additional level of wind protection that is a bit more visually acceptable, snip off the fingertip of an inexpensive unlined knit glove.

This, said Audio-Technica, provides three effective layers against wind noise: foam, porous cloth and a knit outer shell. It is essentially a zeppelin for a lavalier. And the cost is very little.

Of course, it is best to avoid such wind emergencies. Buy the right windscreen for outdoor use to start with and you’ll be protected. The best outdoor windscreens appear as a ball of fur, which in reality encompass sonically transparent, multi-layered wind protection.

Some lavs come with these outdoor windscreens, including Rode’s Lavalier ($249), which includes a Minifur-Lav synthetic fur cover designed for use in outdoor or high-wind conditions. (A package of three extras cost $24.99.)

If the lav you are using has no proper outdoor protection, Rycote makes the lavalier Windjammer ($19.95), which is designed for outdoor use. It reduces wind noise and clothes rustle up to 12 dB and is suitable for interviews or news broadcasts located outdoors in windy conditions.

This windjammer features an elasticized opening and a foam insert to secure the microphone within it. For maximum wind-noise reduction, the windscreen that was included with the lav microphone can be used as well.

Bubblebee Industries makes Windbubbles, miniature imitation fur windscreens for lavs of various sizes. A pair costs $44.95.

Lavalier microphones have become essential tools in news programming and documentary-style interviews. Unless your mic is sold with good outdoor wind protection, look beyond the supplied windscreen. Buy a good outdoor windscreen at the time the mic is purchased. Otherwise, you will make the purchase later — after losing some audio in the field.

Remember, wind noise cannot be fixed in post. If a gust of wind hits your lav mic, the audio is gone forever.