Fringe: Season 2: Episode 12: “Johari Window”
The Fringe team find themselves investigating murders and deformities in a very small, close-knit community. No way there could be some gigantic secret that the whole town is hiding. Nope. The usual medical impossibilities and plot deficiencies aside (which are reported on better elsewhere), this episode contained very little worth commenting on. Check back soon!
The camouflage field is quite a nice concept, but unfortunately way too impractical to be taken seriously. Leaving aside the fact that the eye doesn’t work the way Walter described (it might have been better to say that the EM field altered the brain somehow), what’s more puzzling is how the field can be so selectively applied. The eye takes in light from everything in your field of vision (that’s how you see things), and so the EM field would change the trees, houses, food etc in the same way as the people and butterflies.
Other posters have (correctly) pointed out that EM fields do not hum. However, the hum could potentially be caused by the field generator (or repeater equipment), or an effect like magnetostriction (which causes power lines to hum).