I have the following issue in an iPhone app. The sound almost works, but with some restrictions. More precisely, here is what happens: If I use an earphone connected to my the iPod touch trough a TRS connector I cannot hear anything. If I use an earphone connected to my the iPod touch trough a TRRS connector I can hear without any problem. (I have checked using the apple original Music app, that my connectors are working well) See here for what is a TRS or TRRS connector : http://en.wikipedia.org/wiki/File:IPod_and_iPhone_audio_plugs.JPG The iPod touch I use is as this: Model: PB533J iOS version:4.2.1 (8C148) When I run the same application on an iPad. The sound is only coming out through the speakers and not through the earphone, whatever connector I use. (Here also I have checked using the apple original Music app, that my connectors are working well) The iPad I use is as this: Model: MB294J iOS version:5.5.1 (9B206) Has anyone an idea of what might be the problem? Thanks for any bit of information.