External microphone with mid-2012 Macbook Air

I have a 2011 MacBook Air 13" and I can confirm that the microphone on the original iPhone 4 headphones works when plugged into my Air. They show up as "External Microphone" in System Preferences.

I think that with a Y cable, one could use normal headsets which come with two plugs. There are overpriced Y cables available for recording apps on the iPhone, but I'm sure there are cheaper alternatives.

Note that the MacBooks (also Pro) all have two jacks, one combined for analog/digital out, one for line in. Later, the analog/digital out jack was replaced with analog/digital out, analog in like on the iPhone, but the microphone jack remained. I'm not sure about the current MacBook Pro, but my 2008 unibody MacBook still had two jacks, even though line in was available on the headphone jack, too.

So, regarding your Q: I'm reasonably sure the Bose headphones will work with your Air.

I'm not familiar with your particular set up but generally speaking, when you say "the mic echoes," do you mean that the people on the other end hear their own voices being repeated? If so, could it perhaps be a similar issue to that experienced on some telephone calls?

"The most prevalent cause of echo in PSTN is impedance1 mismatches within the hybrid where 4-wire phone circuits are converted to 2-wire circuits. This electrically generated echo occurs when the incoming energy from the far end speaker is reflected back toward the speaker as a slightly altered and delayed replication due to impedance mismatch in the hybrid.."

More info here: http://www.adaptivedigital.com/product/echo_cancel/echo_explain.htm