Problem with audio quality using Record Audio Comment

I am recording audio comments in Adobe Acrobat Professional using the "Record Audio Comment" tool. The sound quality is bad--very scratchy and has a noisy hum. I am using a good USB headset/microphone. Recordings outside of Acrobat are fine, e.g., in Audacity. I have tried two different microphones with both Acrobat 8 and 9 on two different computers (a desktop and a laptop) with similar results.

I have not found an audio quality setting in Acrobat. Is there some way to improve the audio quality when recording comments? I suspect Acrobat is compressing the audio so much in order to save file size, however, the poor quality makes it almost unusable.

Thanks in advance for any suggestions or advice. I know I can record outside of Acrobat and then add the pre-recorded audio as a comment, but that defeats the purpose.

Bev