Welcome,
Siri is by necessity going to override the important audio unit and audio session settings, so there is a good chance this simply isn’t possible as you’ve specified it. But, something you can try is to set pocketsphinxController.audioSessionMixing = TRUE and making sure that you suspend PocketsphinxController before using Siri and resume it afterwards. To the best of my knowledge _NSLayoutTreeGetBaselineOffsetForGlyphAtIndex is a bug in the Siri UITextView object in iOS 7 and isn’t related to OpenEars, which contains no graphics or typographical code.
Take a look at using OpenEarsLogging and verbosePocketsphinx to learn how to turn on OpenEars’ logging functionality so you can see what is actually happening, since the log messages you mentioned look more like the sample app’s NSLog statements.