I have an audio file that was recorded at 11.025kHz sampling rate. When I play it in Pro Tools (set to 44.1kHz) and examine the frequency spectrum, I get the results I expect--nothing above 5512.5Hz (top image). However, when I use the same plugin in Max (also set to 44.1kHz) to examine the same audio file, I get frequencies going all the way up to 20kHz, but with a dropout at 11.025kHz (bottom image).
In Pro Tools 10, I'm using the AAX version of this plugin, and in Max 6, I'm using the AU version loaded into the [vst~] object. I have the file loaded into a [buffer~] and playing through a [groove~] object with nothing between [groove~] and [vst~] but a patch connection. Setting the sample rate of the [buffer~] to 11025 doesn't seem to make a difference.
Can someone help me understand why I'm seeing the extra "stuff" above the Nyquist frequency? Thanks so much!