Monthly Archives: May 2012

A Valuable Lesson in Audio Interference From Cell Phones

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.

Draft Abstract: Coursera From A Teacher’s Perspective

(this is a draft of an abstract for an upcoming talk I am giving – comments welcome)

The idea of moving educational content to the web to make it more scalable has been around since the mid-1990s. Almost as soon as the web was widely used, one of the first imagined uses would be moving classroom instruction onto the web and achieving economies of scale using the web. While the idea seemed obvious and felt like it would quickly become a solved problem, repeated attempts to replicate the classroom experience at scale achieved only disappointing results. At some point, it seemed to many people that if the problem of teaching on the web at scale remained unsolved after 20 years – that perhaps it was simply not possible. But recently with the breakthrough Stanford AI class with over 160,000 students and the rapid development of efforts like Coursera, Udacity, and edX, it seems like Massively Online Open Courses (MOOCs) are seeing significant investment and amazing growth.

What is different? What has changed? What is unique about MOOCs? Why does it seem like the same idea that has failed so may times before will finally work this time? Will these new MOOCs succeed or be just another hopeful experiment that ultimately fails in the long term?

This talk will look at what it is like to develop and teach a Coursera course from a teacher’s perspective. Dr. Severance is teaching a course titled Internet History, Technology and Security on Coursera on July 23. Teaching with Coursera is part of a long-term effort that he started in 1996, when he developed the first lecture capture system called Sync-O-Matic in order to move his courses to the web when his students were using 28.8 modems. He will look at where Coursera is unique, different, and what is new and compare it to previous effort.

Dr. Charles Severance
University of Michigan School of Information