Согласно документации MSDN , файл, на который указывает поток, имеет очень специфические требования:
The Stream object must point to the head of a valid PCM wave file. Also, this wave file must be in the RIFF bitstream format.
The audio format has the following restrictions:
Must be a PCM wave file
Can only be mono or stereo
Must be 8 or 16 bit
Sample rate must be between 8,000 Hz and 48,000 Hz