hey sorry i'm late to the party here haha !!
I discovered by close examination and experimentation Apple in there infinite sneakiness have added in a little trip up for all 3rd parties making TRRS 3.5mm connectors I've discovered the base perpendicular to the actual jack shaft of the TRRS connector on all Apple approved devices is insulated if its not insulated the mic line can short to the chassis/GND on the iPhone which and MIC to GND activates Siri.
what I've done is wrap the base of the jack in a single layer of 0.2mm Kapton tape a suitable alternative would be well cut gift tape (electrical tape cant be cut that accurately and moves) the issues have now gone for me although the y-splitters I've all tried don't seem to survive more than 6/7 troops and yes jesuit any knock will cause pickup seemingly as any momentary drop in connection is amplified by the voice synth app making it sound wayyy worse. I'm not convinced any 3.5mm female jack will be immune to this as they are all more or less constructed in the same manor with floating contact pins that move when the jack is inserted and as both the socket and the jack can be in motion as opposed to just the jack in the phone there just seems more scope for failure. due to this effect if the iPhone decides the disconnect was long enough it can decide to revert to the internal mic which is feedback city (as my phone and amp sit in the same pocket and total game over as i'm sure you've probably experienced yourself.
Soo going forward
I've been evaluating all sorts of alternatives I think I might have cracked the setup but i'll feedback this week once I can confirm below details what I've tried so you can learn from my mistakes:
My first experiment was to buy a Y-Splitter and solder it direct to a 30-pin dock connector in hopes of a better connection the Audio out was immaculate but i just couldn't work out why the audio in didn't work until I tried my next line of attack..
Then i experimented with the 30-pin edition of the Blue Mikey 2.0 (condenser mic with a 3.5mm line in feed to the dock connector) but quickly found apple hobbled this and my audio in dock connector attempt on iPhone 4 (it still works on the iPhone 3 but the voice synth app doesn't haha .. so that route is dead)
Apple killed the analog lines on the 30 pin connector meaning all audio in via the 30-pin must have its own internal self powered A/D converter and make use of the data feed and as the iPhone 4 was replaced with the 5 there seems to be only one on the market the Fostex AR4i that was build that way I've avoided this as for the time being as it just looked too bulky to be troop friendly but could certainly be a worth while experiment if my next avenue of experimentation should fall through
CURRENT SET-UP:
Using a FiiO Dock connector to pump the audio out of the iPhone into my Aker and a Rode Lavalier Mic designed for the iPhone which uses a TRRS 3.5mm jack which will eliminate a connection point getting shot of flakey Y Splitters
IMHO the two troop friendly set-ups are:
iPhone 5+ setup: (UNTESTED)
Mic/Condenser Mic 3.5mm
Blue Mikey Digital:
http://www.amazon.co.uk/Blue-Microp...41&sr=1-1-catcorr&keywords=blue+mikey+digital
IPhone 5+
Voice Synth Pro
3.5mm out into Aker/Amp
iPhone 4 Setup: (testing in progress)
FiiO L9 Right angle line out dock cable -
http://www.amazon.co.uk/gp/product/B005N6ZAT2?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
iPhone 4
Voice Synth Pro
Rode SmartLav+ -
http://www.amazon.co.uk/gp/product/B00MWECOLK?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
(FYI choose the smartlav+ not the regular smartlav the new + model has a better SNR, better for us helmeted types ^^)
I'll report in my results tomorrow i'll make another evaluation video too !
also ..
I am using two apps actually, one called VoiceChanger which is what I use for real time voice control, the other is Sound About Pro version. Both cost like 2$ US each. The Voice Changer has a bunch of nice options for real time voice effects for its price. The Sound About Pro allows you to completely change how various voice/sound options are handled on your phone. So I could have a small blue tooth earpiece that's easy to finger to receive calls, yet hear and speak through the phone headset/external mic. There really are a bunch of options this gives, so I will figure out how I want to proceed when I get my helmet in the next few weeks.
Does this app work under lockscreen ? as i wasnt aware of any Android ones back when i started that supported that could be a great alternative if it has, modulation, band pass filtering and formant shift/pitchshift