I was out at Coursera Headquarters this past week. After my woes with audio interference with my wireless microphones during some of my recent video shoots, I decided my interview with Daphne Koller would only use wired microphones. I used a wired lavalier mic and wired shotgun microphone. After the shoot was over, I gave a copy of the interview to David Unger (the Coursera AV person and YouTube cover sensation) and we took a quick listen.

Twice in the video there was terrible interference for 1/3 second. Just like in my other pieces. When he heard the first interference, he immediately said – “That is your iPhone – they are horrible for interference”. I was shocked – it was a wired microphone.

Turns out that cell phones and in particular smart phones emit high levels or radiation bursts from time to time. The radiation is so intense and broad spectrum it turns the microphone wire into an antenna and pushes sound into it – it has nothing to do with the wireless bits. You can hear your cell phone cracking speakers from time to time. It is not continuous – just once in a while.

So – we live and learn. Turn off one’s cell phone when doing any interview and have your talent turn off their cell phone and even people nearby that might be helping – every cell phone needs to be off.

Here is a video:

Listen to 0:32

Here is an example of the futility of trying to remove the interference using SoundTrack Pro

Live and learn – From now on turing all cell phones off will be part of my pre-shoot checklist.