The best way to detect unwanted noises is through a pair of headphones. Without headphones, any unwanted noise can easily go undetected, noticed only when you’re importing the footage into the editing tool later. You can use closed‐back headphones, which surround the ears and cut out most of the noise coming from the outside, so that the person monitoring sound can mainly hear what is being picked up by the microphone. These can be expensive, but a budget pair starts at only around $10.
If you hear a distracting background noise through the headphones when filming, such as from a plane, gust of wind, or passing car, stop filming and wait for the sound to pass, and then retake that shot. If the sound of a plane appears in the background in one shot and not in the next, the sound will be uneven between shots, and this will sound odd for your audience.
The following list describes a few ways to avoid recording unwanted noises during filming:
Turn off any air-conditioning units or fan heaters while filming. Microphones can pick up noises that sometimes humans can’t even hear when filming.
Make sure all cellphones are off or on silent when filming because if they go off, they can bring a shoot to a stop. Also, sometimes a cellphone’s roaming or searching signal can interfere with the camera and can be heard on the recorded audio.
Avoid pointing the microphone in the direction of any clear background noise, including roads, waterfalls, or fountains. Again, these sounds can come across clearly in the recording and can make it hard to hear dialogue.
Avoid filming in empty rooms because they can create distracting echoes in your recording (unless, of course, you want echoes in your film). To eliminate echoes, place hand blankets on walls to help deaden the sound.