To access the data you use the reader's Read method:
var myReader = new WaveFilereader(filename);
int bytesRead = 0;
var readChunck = new byte[1024];
do
{
//Read 1024 bytes at a time, will return 0 when there are no more bytes to Read
bytesRead = myReader.Read(readChunk, 0 , readChunk.length );
//Process the bytes here
}
while(bytesRead != 0)
Alternatively you can make your life easier by just resample the audio using the media foundation resampler.You can downsample the audio with the Media foundation resampler by doing something like this:
//Read 2-channel Audio with sample rate 44.1Khz
var myReader = new WaveFileReader(filename);
//New Waveformat has 2-channels and sample rate 22KHz
var myOutputFormat = new WaveFormat(22000,2);
//Resample
var resampledAudio = new MediaFoundationResampler(myReader, myOutputFormat)
{ ResamplerQuality = 60 });
For more info on Audio Conversion see THIS.