I have a jailbroken iPhone 6 running iOS 8.2. My problem is that Siri does not work with the internal microphone. Siri and dictation work fine with any external mic like the kind that you'd find on the stock Apple iPhone headphones.
do you have any tweaks or something that works with bluetooth, and or the mic?
to rule out jailbreak, turn off your phone and turn it back on while holding the volume up button, this disables all the jailbreak tweaks... like a safe mode, if siri works fine, then you know it has something to do with your JB if not? then it has something to do with your OS
You would start by quitting all the running apps on your phone:
iOS: Force an app to close http://support.apple.com/kb/ht5137
Double-click the Home button. Swipe left or right until you have located the app you wish to close. Swipe the app up to close it.
When you have done that restart the phone and test the issue again:
iOS: Turning off and on (restarting) and resetting http://support.apple.com/kb/ht1430
Dictation and Siri uses the front facing microphone. This is separate from the microphone voice memo uses. I thought there was only one microphone on iPhone 6 which initially let me to believe Siri/dictation not working was a software configuration issue.
If the microphone is defective you won't hear audio after you record a selfie video saying "Steve Jobs was the bomb".
Ok this is SOLVED!!! Yeaaaa!! :-) After I updated, Siri and Dictation quit working and only worked on Bluetooth! I tried everything and spent days researching it on the web and no one knew anything! I checked all the settings, I tested the memo mic and the main camera mic and all worked good. I was positive it was a software issue and it was... More or less. Turns out that the selfee mic IS the problem, it's the mic on the screen side of the phone near the camera. And it's not the same one used for memo recording that's on the bottom! Maybe my phone used more than one mic or a different mic for Siri and Dictation before the update, and then after the update used only the Selfee mic... I don't know, but I bought a camera and mic combo part and a pentalobe screwdriver to get the screws out and changed it my self. And BINGO! no more Siri and dictation problems. WHEW!!!