added the option to set audio sample rate (as much as selected codec allows..) via flashvar soundRate, as well as JS API getter-setter getMicrophoneRate and setMicrophoneRate.
Optional values listed here (http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/media/Microphone.html#rate), see also note about accepted values taken from here (http://help.adobe.com/en_US/as3/dev/WS5b3ccc516d4fbf351e63e3d118a9b90204-7d1d.html#WS5b3ccc516d4fbf351e63e3d118a9b90204-7d0d):
Higher sample rates increase sound quality, but they also create denser data streams that use more resources for transmission and storage. The Microphone.rate property represents the audio sample rate measured in kilohertz (kHz). The default sample rate is 8 kHz. You can set the Microphone.rate property to a value higher than 8 kHz if your microphone supports the higher rate. For example, setting the Microphone.rate property to a value of 11 sets the sample rate to 11 kHz; setting it to 22 sets the sample rate to 22 kHz, and so on. The sample rates available depend on the selected codec. When you use the Nellymoser codec, you can specify 5, 8, 11, 16, 22 and 44 kHz as the sample rate. When you use Speex codec (available starting in Flash Player 10 and Adobe AIR 1.5), you can only use 16 kHz.