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On-Location Audio – 3 Tricks Every Filmmaker & Sound Person Should Know

Danny Greer

Reducing background buzz and hum when recording location sound can be a challenge!  Follow these 3 simple tips to get cleaner location sound on your next shoot.

Want to drive yourself crazy? Try removing audio buzz or hum during video editing.  Isolating bad audio frequencies without distorting dialogue, or intentional on-camera sound, can be a frustrating challenge.

It’s always best to get the cleanest on-location sound.  You’ll save yourself time in post-production and will likely have a better sounding product then if you were to attempt a post-production fix.

3 common sources for on-location background buzz and hum are:

  • Heating, Ventilation and Air Conditioning Systems
  • Lighting
  • Refrigerators

The following on-location sound tips will address each of these problem sources and how to minimize their effect on your audio.

Play Weatherman

On Location Audio Air Conditioner HumA/C units may be the #1 culprit for picking up bad background audio.  They rumble, hum and can really muddy up an audio track.  To top it off, they’re erratic…turning on and off at random intervals (leading to irksome shot inconsistencies).  The only way to insure that you don’t get A/C hum is to kill the system while you’re shooting.  BUT, nobody likes burning up under hot production lighting…

TRICK:  As soon as you arrive on set (figure, you’re going to arrive about an hour or more early to setup lighting, shots, etc.) radically adjust the heater or A/C unit.  Let the unit overcompensate.  If it’s hot out, turn the air conditioner on blast.  Freeze the room.  In cold weather do the opposite.  Then, when you’re ready to start rolling, turn off the unit.  This trick will buy some time where the talent and crew aren’t miserably uncomfortable on set.

Blankets & A Step Stool

So what about the times when you can’t control the A/C unit?  Big office buildings are notorious for this…

Sound Blankets Location Audio Tip

TRICK:  You can soften the A/C unit hum by covering up vents with blankets.  Professional sound blankets are ideal, but if you’re on a budget or in a pinch, even your standard blanket or comforter could be a satisfactory replacement.  The step stool allows you to access high or hard to reach vents.

If you have buzzy ballasts from location lighting, obviously the first line of attack is to turn them off.  Lighting that stays on all the time (such as emergency lighting) may require you to physically remove the bulb while shooting.  The step stool also aids with this.

Freeze the Keys

Audio Refrigerator Hum KeysRefrigerators can’t be easily moved out of a location, so it’s best just to turn the power off while rolling on-set.  With the door shut, a refrigerator can stay cool for a while…but you don’t want to forget to turn it back on!

TRICK: Remember to power it back on before leaving the set by placing your keys in the refrigerator when you unplug it (tip from MacProVideo.com).  There’s no quicker way to get banned from a location than to let a refrigerator full of food spoil!

For on-location audio success, follow these tips for reducing background buzz and hum noise before the cameras ever start rolling!

Do you have tips for getting cleaner location audio?
We want to hear from you in the comments!