iOS SDK Disable Internal Microphone

I am developing an iOS application that receives data through the auxiliary port 开发者_StackOverflow社区(microphone).

We got oscilloscopes hooked up and are at the point where we can measure frequencies and amplitudes on a testing iPhone.

However, even with the auxiliary cable connected, the iPhone still listens to the internal microphone in addition to our external AUX input thus watering down our measurements.

The iPhone definitely recognizes the connected AUX cable (internal speakers are turned off).

Is there any way to programmatically disable the built-in microphone?

or

Is there some special signal we can send through the AUX port to disable the internal microphone?

After much research on this topic, there is no way to do it at this moment in time.

If you look at the Audio Session Programming Guide and the AVCaptureDevice Class Reference, all the properties relating to the devices input sources and audio routes are readonly.

If it's of any use, you can detect whether or not headphones or an external mic are plugged in. Here's a question relating to that.

I don't believe you can disable the built-in microphone without the user physically pressing the silent switch, but maybe you could store the data recorded by the built-in mic and then filter it out of the measurements taken by the oscilloscopes? I don't know how you would go about implementing this; it's just a theory.

Hope this helps!