The old answer for this question is now incorrect; the iOS Simulator now supports audio input/recording.
Pic below related: where you set your audio input device (defaults to your system default)
Also be warned, some online Apple dev docs still say audio input is unsupported by the simulator ("as of 8.2") even though it is with newer versions...
Edit: Screenshot from OS X 10.12 (Sierra), Xcode 9.1 (function is also available in later Xcode 8, > 8.2)
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