[jwhendy]

First post here... I've been wanting to get some new IEMs, and part of the justification (wife involved!) is that it'd be great to have ones with a built-in mic for phone calls, and particularly Skype/Google Talk, as the sound is horrible when the built-in phone/computer mic can hear the speaker output.
 
I've been lurking, reading lots of threads, and trudging through some of the massive IEM comparison posts. A lot of highly reviewed IEMs don't have a microphone version, which is a bummer in my case. That had me considering getting a cheapo headset + mic for calls and splurging for a nice IEM anyway since the primary function will be listening to music (> 95%) and only secondarily using voice (< 5%) (but then I lose my justification... then again, wouldn't be the first time!).
 
Since I'm naturally reading posts about in-line-mic-having IEMs, every so often I run into statements like this one, which I've seen at least a few times though I can't seem to find more examples at the moment:
 
Quote (hitme987):

Its really hard to get a good IEM with inline microphone. If you want mic, you must compromise the sound quality.

 
There could be several sources for the claim (just a brainstormed list):

1. To include additional electronics, sound quality is compromised to keep costs similar to the non-mic version (a function of budget rather than causation)
2. Manufacturers tailoring to phone-use products don't produce the same sound quality as those who simply produce headphones for the sake of audio alone (an instance of correlation, not causation)
3. [Fill in your explanation here]
4. The only reason I'm really interested in: There's a scientific reason (i.e. electronics/physics based) that including an in-line microphone affects sound quality (actual causation)

 
So... which one is it? If there's a scientific basis for the claim, perhaps I'll bypass inline mic options and use a much lower-tier product for voice calls. If not, perhaps you can chime in on the reason you think this statement circulates? For an entirely differnet avenue, feel free to state that it's not the case.
 
Thanks for any input for someone trying to understand all of this!
 
P.S. My prediction is that it's not a case of scientific causation, but some sort of correlation being involved (great models with mics are just rarer, for example). As an engineer with at least a little electronics knowledge and from reading on Wikipedia about headphone jacks, my initial read suggests that audio and microphone-related signals are completely separate (audio on tip/1st ring and mic/call-button on 2nd ring/outer sleeve). Thus I'm not sure why quality would be affected by including a microphone... shielding issues when running those signals next to each other? Overall impedance? Not sure...

 

[jwhendy]

Mods: noticed that there is a sound science sub-forum. Perhaps this would fit better there? Sorry for the inconvenience.

 

[soundstige]

No basis. It's only said to refer to few top-tier IEMs being offered with without a mic cable.

 

[jwhendy]

@soundstige: as in these top-tier IEMs have both mic and non-mic versions and the non-mic version is superior? Or did you mean something else?

 

[soundstige]

I'm sorry, I meant the opposite -- "without", not "with". 
Quote:

@soundstige: as in these top-tier IEMs have both mic and non-mic versions and the non-mic version is superior? Or did you mean something else?

 

[jwhendy]

@soundstige: Ah, so your estimate is that it's most like my second bullet point: those manufacturers who make products with mics just aren't at the level of some of the higher sound quality manufacturers who don't offer mic'd versions. I could definitely see that, as I ran into this as a newbie looking into good entry-mid level options.
 
There's fantastic things said about VSonic ... and I never saw any with mics. Same for Dunu and Hifiman.
 
Thanks for the response!